SRC Users' Meeting - Synchrotron Radiation Center - University of ...

Welcome to the 36 th SRC Users’ Meeting!
John Joyce
UM2003 Chair
At this meeting you will learn of the status of the
SRC, find out who is the Aladdin Lamp Award
winner, listen to talks given by researchers, and
participate in a poster session (and best poster
contest!).
The Synchrotron Radiation Center (SRC) is a
national facility open to all qualified investigators.
It is operated by the University of Wisconsin-
Madison with funding primarily from the National
Science Foundation. Use of the “Aladdin”
electron storage ring is made available free of
charge to scientists who perform research
publishable in open literature. Propriety research can be conducted based on
full cost recovery.
Synchrotron Radiation based research at the SRC is performed in a large
variety of disciplines such as atomic and molecular physics, surface science,
material science, semiconductor research, chemistry, infra-red spectroscopy,
biology, nanotechnology, photoelectron microscopy, and geology.
This booklet contains a few examples of the many research projects
conducted at the SRC.
We hope you will enjoy this Users’ Meeting!
Acknowledgement
We wish to thank all contributors to this booklet, in particular Users of the SRC facility.
Financial support for the Synchrotron Radiation Center from the National Science
Foundation under Award No. DMR-0084402 is gratefully acknowledged.

36 th SRC Users’ Meeting
Saturday, October 25, 2003
(Location of Meeting: PSL Large Conference Room)
PROGRAM
8:00 - 8:30 Registration, refreshments
SESSION 1 Chair: Hartmut Höchst
8:30 -8:50 Welcome & Status of SRC, Joe Bisognano, Executive Director
8:50 - 9:10 Mark Bissen, SRC
“Current and Future Status of SRC Beam Lines”
9:10 – 9:25 Bob Legg, SRC
“Operations 2003”
9:25 – 9:40 Ken Jacobs, SRC
“Accelerator Developments”
9:40 – 10:25 Announcement of Aladdin Lamp Award Winner:
Christian Ast, Physics, UW-Madison (now at Max-Planck-Institut)
“Interactions in the Photoemission Process for Materials with
Low Conductivity”
10:25 – 10:40 Break
SESSION 2 Chair: Cliff Olson
10:40 - 11:20 George Sawatzky (invited), University of British Columbia, Vancouver
“High Energy Research Possibilities with an Extended
Photon Energy Range”
11:20 – 11:35 Juan Carlos Campuzano, U of Illinois at Chicago
“A High Resolution, High Photon Energy Capability at Aladdin, the
Instrument and the Science”
11:35 –11:50 Tom Miller, U of Illinois at Urbana-Champaign
“Atomically Uniform Thin Films on Silicon”
11:50 –12:05 S. H. Southworth, Argonne National Lab
“Many-Electron Effects On The Xe 5s Nondipole Photoelectron
Asymmetry”
12:05 –12:20 Adam Kaminski, University of Wales – Swansea
“New features in the phase diagram of cuprates”

12:20 - 1:10 Lunch
1:10 –1:45 Posters at Aladdin, Aladdin Tours
SESSION 3 Chair: Tom Miller
1:45 –2:00 Scott Whitfield, U of Wisconsin – Eau Claire
“Photoelectron Spectrometry of Atomic Chromium in the Region of the 3p
to 3d Giant Resonance”
2:00 –2:40 Jim Tobin (invited), Lawrence Livermore National Lab
“Spin-Resolved PES of Complex Systems”
2:40 –2:55 Tomasz Durakiewicz, Los Alamos National Lab
“Photoemission Study of USb and UTe – 5f Electronic Structure and
Magnetism”
2:55 – 3:10 Cherice Evans, Queens College – CUNY, Flushing, NY
“Field Ionization of CH 3 I in Supercritical Ar”
3:10 –3:25 Break
3:25 – 4:05 Users' Meeting (election, discussion of new beam lines, etc.)
SESSION 4 Chair: Dave McIlroy
4:05 –4:25 Astrid Jürgensen, CSRF
“Canadian Synchrotron Radiation Facility”
4:25 - 4:40 James W. Taylor, Center for NanoTechnology (CNTech)
“Future Plans and Recent Accomplishments at CNTech”
4:40 – 4:55 Paul Nealey, CNTech and Chemical Engineering, UW-Madison
“Self-assembly of Block Copolymers on Lithographically Defined
Nanopatterned Substrates”
4:55 –5:10 Brad Frazer, UW-Madison & Institute de Physique Appliquée, Lausanne
“Identification of Sub-micrometer Silicate Inclusions in Archean Zircons
with X-PEEM”
5:10 – 5:15 Best Poster Contest Winner
6:00 – 7:00 Cocktail Hour at Dry Bean Saloon & Steakhouse - Madison
(hors d’ouevres provided; cash bar)
(directions to the Dry Bean are enclosed in registration packet)
7:00 Dinner at Dry Bean
_______________________________________

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Administration
Executive Director
Dr. Joseph Bisognano
Scientific Directors
Professor Juan Carlos Campuzano
Scientific Director for Condensed Matter
Professor Gelsomina "pupa" De Stasio
Scientific Director for Multidisciplinary Science
Professor James Taylor
Scientific Director for Educational Programs
__________________________________
UM2003 Organizing Committee
Program Chair
John Joyce, Los Alamos National Laboratory
Local Committee
Hartmut Hchst
Pamela Layton
Michelle Kirch
Christopher Moore

T
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L
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STATUS OF THE SRC BEAMLINES AND INSTRUMENTATION
M. Bissen
SRC, Univ. of Wisconsin, 3731 Schneider Dr., Stoughton, WI-53589
The Instrumentation Group maintains the SRC and SRC/PRT monochromator beamlines on
Aladdin for use by the scientific community. The technical details of these instruments and the
PRT and CnTech beamlines is available on-line at www.src.wisc.edu. Thus, instead of repeating
that information, this report will focus on current uses of the existing beamline and progress for
the new beamlines currently under development. Also, the Group operates a variety of
experimental endstations that are available to the User community.
Initial operation of the Wadsworth beamline on the U2 undulator is planned for Fall 2003.
The beamline will cover the range from 8 to 50 eV utilizing the high brightness undulator source
for ARPES experiments.
An additional beamline from U2, the VLS-PGM, is being constructed for PEEM experiments
requiring high brightness. The proposed variable line spacing monochromator will cover the
range from 60 to 2000 eV with a resolving power of nearly 1000. For this mode of operation, the
U2 undulator will be operated as a wiggler at maximum k value (4.69). Commissioning is
currently scheduled for summer 2004.
An update on the NIM classic maintenance and a progress report on the PGM repairs will be
presented as well as future plans for upgrades of some of the facility experimental chambers.
In addition, results of the recent U1 NIM and Scienta SES 2002 will be shown.
This Users’ Meeting is supported by the National Science Foundation, Grant No. DMR-
0084402.

SRC OPERATIONS
Bob Legg
SRC provides beam in scheduled 3-week experimental quantums. There is a scheduled
one-week “Development Week” for maintenance after every two quantums. Each week of an
experimental quantum is scheduled from 8 AM Monday until 8 AM Saturday; five days, 24
hours a day. Saturdays are used for holiday make-up and to provide users with additional beam
time. Each day during the week has four injections, 8 AM, noon, 6 PM and midnight. The noon
to 8 AM period is considered scheduled beam for users. SRC over the year ending 10/1/2003
provided the normal 4271 hours of scheduled beam with a 98% reliability. The hours of
operation can be broken down into 3636 hours of 800 MeV beam and 634 hours of 1 GeV beam.
Saturdays and morning beams accounted for an additional 887 hours of user beam. The major
source of downtime for the year was intermittent equipment failure.
Operations have continued to be dynamic. The group changed this year with the
departure of swing shift operator, Dan Granger, and his replacement by Craig Trewartha. As a
group we worked to complete several projects left from previous years (vacion readbacks,
Diagnostic front ends, U3 Control interface, etc.). There was continued effort in the installation
of the user utilities on the Wadsworth beamline. We also assigned a specific electronic
technician to become a schematic draftsman, specifically responsible for AutoCAD support of
the SRC electrical drawings. This was done to convert some of the original hand sketches of
Aladdin systems to appropriate, dated, drawings.
Operations are also working to improve operator training. With the advent of the
automated “One Button” setups for Aladdin, many of the operators don’t get time doing machine
setup and control during normal user operations. To maintain their ability to deal with the off
normal situations, Operator training has been instituted during the development periods. By
improving Operator capabilities and addressing weaknesses in the installed machine, operations
will continue to make the machine more reliable in the year to come.

ACCELERATOR DEVELOPMENTS
Ken Jacobs
Synchrotron Radiation Center, University of Wisconsin - Madison
3731 Schneider Drive, Stoughton, WI 53589-3097
Work has continued on a variety of accelerator developments at the SRC over the
past year. The low emittance operating mode “LF15” is now routinely run for all
800 MeV beams. This gives a factor of three reduction in horizontal beam size, with
unchanged vertical beam size and beam lifetime. The exception to routine LF15 running
is when vacuum work is done in the ring, after which Base Lattice is run for the first few
weeks.
LF15 cannot be run at 1 GeV due to power supply, cabling, and magnet
limitations. For reduced emittance at 1 GeV, an alternate lattice with emittance between
LF15 and Base Lattice has been designed. Operation will require upgraded cables on
some of the quadrupoles, and this is presently being pursued. However, LF15 can be run
at 950 MeV, requiring only the cable upgrades. Tests of 950 MeV LF15 have been
encouraging. We are also investigating other low emittance 950 MeV lattices.
We continued to make improvements made in beam stability. An additional
feedback loop was installed in the main RF system to reduce coherent synchrotron
oscillations of the beam. This, combined with a general reduction of 60 Hz harmonics on
the beam, has reduced noise levels on the infrared beamlines so that they can now be
used when running low emittance beam. Undulator compensation has progressed to the
point that U1 and U3 can now be scanned over their full ranges in LF15. Compensation
work is continuing with U2, and in Base Lattice.
In an effort to improve beam lifetime, we are continuing studies to more fully
understand beam loss mechanisms. To increase lifetime, it may be necessary to open up
some limiting apertures in the ring.
Other projects completed over the past year include upgrading the accelerator
control system CPUs, coating the injection kicker ceramics to reduce wakefields and
radiated RF, and installation of a modern scripting language on the control system.
Scripts are used to simplify accelerator operations, implement control algorithms to
improve beam stability, and perform experiments during accelerator development
periods.

INTERACTIONS IN THE PHOTOEMISSION PROCESS OF
MATERIALS WITH LOW CONDUCTIVITY
Christian R. Ast
Max-Planck-Institut für Festkörperforschung, Stuttgart, Germany
Scattering of the photoelectron is an omnipresent phenomenon in photoemission
spectra. In most cases inelastic scattering manifests itself in either discrete loss structures,
a featureless background or an asymmetric line shape. Two examples are presented in
which increased interactions of the photoelectron with its surroundings lead to additional
emission features in the photoemission spectra of the semimetal bismuth. Scattering
events can be seen in core level spectra as structured loss features from interband
transitions. In valence band spectra, scattering processes can contribute additional
structures from secondary cone emission.
Spectra of the Bi 5d core level show an additional peak split off in energy
between 160 and 260meV, which can be related to momentum dependent energy losses
suffered by the photoelectron from interband transitions. Similar phenomena have been
observed in the 4d core levels of Sb, which leads to the conclusion that loss features are
enhanced in materials with low conductivity and low charge carrier concentration.
Valence band spectra of Bi(111) at normal emission as a function of photon energy show
multiple emission features from the same initial state band. These emission features can
be attributed to primary and secondary cone emission. To be observed in the normal
emission spectra photoelectrons from secondary cone emission have to be scattered back
into the normal emission direction. Accounting for the secondary cone emission in the
analysis of the final state dispersion, it is than possible to experimentally determine the
deviations of the final states from the free electron band structure. With these
experimentally determined final state bands on hand, it is than possible to extract the
initial state band structure E i (k).

HIGH ENERGY RESEARCH POSSIBILITIES WITH AN
EXTENDED PHOTON ENERGY RANGE
George Sawatzky
Department of Physics, University of British Columbia, Vancouver
No abstract provided.

A HIGH RESOLUTION, HIGH PHOTON ENERGY CAPABILITY
AT ALADDIN, THE INSTRUMENT AND THE SCIENCE
J. C. Campuzano
University of Illinois at Chicago, Department of Physics,
845 W. Taylor, M/C 273, Chicago, IL 60607
No abstract provided.

ATOMICALLY UNIFORM THIN FILMS ON SILICON
M. Upton, T. Miller, and T.-C. Chiang
Department of Physics, University of Illinois at Urbana-Champaign, 1110 West Green Street,
Urbana, Illinois 61801-3080
Frederick Seitz Materials Research Laboratory, University of Illinois at Urbana-Champaign,
104 South Goodwin Avenue, Urbana, Illinois 61801-2902
The continued miniaturization of silicon-based electronic devices is pushing component
layer thicknesses toward the nanoscale, and a critical hurdle along this path is atomistic
fluctuation. An uncertainty in layer thickness or roughness at the monolayer level can lead to
substantial and unacceptable property variations. The effect is generally on the order of 1/N,
where N is the thickness of the film in terms of monolayers (ML). At the nanoscale, 1/N can be
as large as 20%, and for a typical valence band width of ~10 eV, the resulting changes in the
electronic structure can be severe or even catastrophic for device performance. Exact control of
layer thickness and atomic uniformity is thus a critical issue, but so far has not been achieved for
films grown on silicon. Yet this is extremely important in view of the vast technological and
manufacturing base for the silicon industry. In this work, we show that Pb deposition on Si(111)
at 100 K can lead to atomically uniform thin films provided that the Si substrate is pretreated
appropriately. The resulting films support quantum well states [1-3] due to confinement of
electrons in the Pb films by the band gap in the Si substrate. A measurement of such states by
angle-resolved photoemission determines the film
thickness and reveals a quantum electronic structure
that varies substantially as the film thickness
undergoes monolayer changes. The result is a rather
dramatic contrast between films consisting of even
and odd numbers of monolayers. These findings
illustrate the importance of atomic layer precision for
controlling the electronic structure of thin films.
Our angle-resolved photoemission measurements
were performed at the Synchrotron Radiation
Center, University of Wisconsin-Madison, using a
Scienta analyzer equipped with a two-dimensional
detector. The Si(111) substrates were prepared from
commercial n-type wafers with a resistivity of 1-60
Figure 1: The three-dimensional plot
above shows the photoemission
intensity as a function of Pb film
thickness and binding energy
relative to the Fermi level. Three
major quantum well peaks are seen
at thicknesses N = 5, 7, and 9. A
weak resonance peak at higher
binding energy is seen at N = 8.
ohm-cm. The Pb films were prepared by sequential,
incremental deposition at 100 K, and the
photoemission spectra were taken with the sample at
the same temperature. The three-dimensional color
plot in Fig. 1 shows the normal-emission intensity as
a function of binding energy and film thickness.
Three major peaks, at binding energies of 0.40, 0.26,
and 0.15 eV below the Fermi level, attain their
maximum intensities at film thicknesses N = 5, 7, and
9, respectively, while no such peaks are observed at

the even layer thicknesses N = 6 and 8 in the same energy range. These peaks represent quantum
well states formed by confinement of the Pb p-band electrons by the Si band gap. No such
quantum well states exist for N = 6 and 8, as will be explained below.
The appearance of intense peaks for odd N only has to do with the specific band structure
of Pb and the Si band gap. From data taken over a wide thickness range, it is concluded that the
Fermi level of the Pb is at 0.5 eV above the Si valence band edge. Electrons in the Pb film with
binding energies within 0.5 eV of the Fermi level are thus confined by the Si band gap, giving
rise to sharp and intense quantum well peaks. Electrons at higher binding energies are not
confined. Nevertheless, partial reflection at the Pb-Si boundary can give rise to resonances which
appear in photoemission as weak and broad peaks [3]. One such weak resonance peak at a
binding energy of 0.63 eV can be seen in the three-dimensional plot of Fig. 1 at N = 8. Further
evidence for the confinement edge is seen in the line scan of the peak at N = 5 in Fig. 1. This
peak, with a binding energy very close to the confinement edge, is asymmetric. Its higherbinding-energy
side is substantially broader because this portion of the spectral weight lies
outside the confinement range. From the confinement range of 0.5 eV and the known Si band
gap of 1.2 eV, a Schottky barrier height of 0.7 eV is deduced for our n-type Si substrate. This is
consistent with a recent reported value of 0.72 0.02 eV based on electrical measurements [4].
The binding energies of quantum well states are determined by the Bohr-Sommerfeld
quantization rule [2, 3, 5]:
2kNt
s
i
2n
, (1)
6 where k is the wave vector, t is the monolayer
0
thickness,
s
is the phase shift at the surface, i
is
5
the phase shift at the interface, and n is a quantum
1
number. For a given N and integer quantum
4 numbers, this equation determines the allowed k
values, which in turn determine the binding energies
2
3 of the quantum well states through the band
dispersion relation E(k). For Pb(111), the relevant
3
2 band is the p valence band with a known dispersion
that extends from 4.2 eV below the Fermi level to
Binding Energy (eV)
4 n = 0
0 2 4 6 8 10 12
Thickness N (ML)
Figure 2: Binding energies of quantum
well states (circles connected by lines)
deduced from a fit to the experimental
results (crosses). The band structure of
Pb and the phase shifts enter the model
calculation. The only fitting parameter
is an unknown constant offset in the
interface phase shift. The quantum
number n for each branch is indicated.
1
8.0 eV above the Fermi level [5]. The surface phase
shift
s
as a function of energy has been computed
by a first-principles method [5], and this is used in
the present analysis. The interface phase shift i
is
given by
1
E E
L
Re
cos
2
1
0
, (2)
EU
EL
where Re refers to the real part, E is the energy, EL
is the lower edge of the Si band gap, E
U
is the upper
edge, and 0
is a constant [6, 7]. It is easy to verify
that
i
changes by across the Si band gap. The
only unknown quantity in Eq. (1) is the constant
0
.
This is treated as a fitting parameter in a fit of the

calculated binding energies of the quantum well states to the observed values. The calculated
binding energies of the quantum well state from the fit are shown as open circles connected by
lines in Fig. 2, and the quantum number n for each branch is indicated. The results agree well
with the experimental values shown as crosses. The experimental value for the quantum well
state at N = 11 is not included in the figure because the peak is too close to the Fermi level for a
precise determination of its position.
The confinement edge at 0.5 eV is indicated by a horizontal dashed line in Fig. 2. In
agreement with experimental observations, no quantum well states exist, or only weak
resonances are observed, for even N = 4, 6, 8, and 10, while intense quantum-well states are
observed for odd N = 5, 7, and 9. This difference between even- and odd-N configurations is just
a consequence of the way that the quantum well states evolve as a function of thickness as seen
in Fig. 2. This evolution is largely determined by the band structure [3, 5, 8, 9]. It happens that
one half of the Fermi wave length in Pb is approximately two atomic layers, and a simple
analysis based on Eq. (1) shows that a new quantum well state drops below the Fermi level for a
film thickness increment of about two atomic layers [3, 5]. The corresponding changes in the
occupied density of states should give rise to an oscillation period of about two atomic layers for
essentially all physical properties of the films. Also in agreement with our experimental
observation is that no quantum well states are predicted for N = 1-3.
Numerous groups have experimented with Pb growth on Si [8-13], but none has achieved
atomic uniformity. Prior to this experiment, we had performed extensive experimentation with
direct deposition on the (7x7) reconstructed Si(111) at various temperatures, but the resulting
films were inevitably rough. In the present experiment, the atomic-layer uniformity is achieved
by first preparing either the or 3 3
reconstructions [12, 14, 15]. Our experiment
shows that deposition of Pb on the phase, the phase, or any intermediate phases at a low
temperature (100 K) leads to atomically uniform films. The final results are the same for the
same total amounts of Pb deposition including the initial Pb coverages. The determination of
film thicknesses is described in detail in [1].
The stability of the films has been measured, and some interesting features were
observed, including the bilayer oscillation predicted by Wei et al. [17].
Why does Pb pretreatment promote uniform film formation, while direct deposition on
Si(111)-(7x7) does not work? A possible explanation is that the (7x7) surface, with its
complicated reconstruction involving adatoms, dimers, corner holes, and partial stacking fault, is
not smooth on the atomic scale. These structural features can pin the Pb growth locally at low
temperatures, resulting in small crystallites that are structurally incoherent. Increasing the
substrate temperature to promote long-range diffusion and structural coherence leads to
formation of islands instead of smooth films due to electronic effects [10, 16]. Pretreatment of Si
by Pb leads to a smooth bulk-terminated Si substrate with a well ordered Pb overlayer. This can
be a good template for smooth growth upon further deposition at low temperatures. Our results
illustrate an important issue in film growth – the initial surface structure can be a deciding factor
for the morphological development of films. As shown in this study, proper conditioning of the
starting surface allows us to make uniform films on Si, a result of potential interest and
importance for nano and quantum electronics.
This work is supported by the U.S. National Science Foundation (grant DMR-02-03003).
We acknowledge the Petroleum Research Fund, administered by the American Chemical
Society, and the U.S. Department of Energy, Division of Materials Sciences (grant DEFG02-
91ER45439), for partial support of the synchrotron beamline operation and the central facilities

of the Frederick Seitz Materials Research Laboratory. The Synchrotron Radiation Center of the
University of Wisconsin-Madison is supported by the U.S. National Science Foundation (grant
DMR-00-84402).
References:
[1] M. Upton, T. Miller, and T.-C Chiang, Phys. Rev. B, in press.
[2] J. J. Paggel, T. Miller, and T.-C. Chiang, Phys. Rev. Lett. 81, 5632 (1998); Science 283,
1709 (1999).
[3] T.-C. Chiang, Surf. Sci. Rep. 39, 181 (2000), and references therein.
[4] A Schottky barrier height of 0.93 eV was reported by D. R. Heslinga, H. H. Weitering, D. P.
van der Werf, T. M. Klapwijk, and T. Hibma, Phys. Rev. Lett. 64, 1589 (1990). In a more
recent study by R. F. Schmitsdorf and W. Mönch, Eur. Phys. J. B 7, 457 (1999), a value of
0.72 0.02 eV was reported.
[5] C. M. Wei and M. Y. Chou, Phys. Rev. B 66, 233408 (2002).
[6] D.-A. Luh, T. Miller, J. J. Paggel, and T.-C. Chiang, Phys. Rev. Lett. 88, 256802 (2002).
[7] N. V. Smith, Phys. Rev. B 32, 3549 (1985).
[8] A. Mans, J. H. Dil, A. R. H. F. Etterma, and H. H. Weitering, Phys. Rev. B 66, 195410
(2002).
[9] M. Jalochowski, H. Knoppe, G. Lilienkamp, and E. Bauer, Phys. Rev. B 46, 4693 (1992);
M. Jalochowski, M. Hoffmann, and E. Bauer, Phys. Rev. B 51, 7231 (1995); Th. Schmidt
and E. Bauer, Surf. Sci. 480, 137 (2001).
[10] M. Hupalo and M. C. Tringides, Phys. Rev. B 65, 115406 (2002). M. Hupalo, V. Yeh, L.
Berbil-Bautista, S. Kremmer, E. Abram, and M. C. Tringides, Phys. Rev. B 64, 155307
(2001).
[11] W. B. Su, S. H. Chang, W. B. Jian, C. S. Chang, L. J. Chen, and T. T. Tsong, Phys. Rev.
Lett. 86, 5116 (2001).
[12] I.-S. Hwang, R. E. Martinez, C. Liu, and J. A. Golovchenko, Surf. Sci. 323, 241 (1995).
[13] I. B. Altfeder, K. A. Matveev, and D. M. Chen, Phys. Rev. Lett. 78, 2815 (1997).
[14] J. A. Carlisle, T. Miller, and T.-C. Chiang, Phys. Rev. B 45, 3400 (1992).
[15] P. J. Estrup and J. Morrison, Surf. Sci. 2, 465 (1964).
[16] Hawoong Hong, C. M. Wei, M. Y. Chou, Z. Wu, L. Basile, H. Chen, M. Holt, and T.-C.
Chiang, Phys. Rev. Lett. 90, 076104 (2003).
[17] C. M. Wei, and M. Y. Chou, Phys. Rev. B 66, 233408 (2002).

MANY-ELECTRON EFFECTS ON THE XE 5S NONDIPOLE
PHOTOELECTRON ASYMMETRY
S. H. Southworth 1 , E. P. Kanter 1 , B. Krässig 1 , R. Guillemin 2 , O. Hemmers 2 ,
D. W. Lindle 2 , and R. Wehlitz 3
1 Argonne National Laboratory, Argonne, IL 60439*
2 University of Nevada, Las Vegas, NV 89154
3 SRC, University of Wisconsin, Stoughton, WI 53589
Photoionization of the Xe 5s subshell has been extensively studied because of its
sensitivity to relativistic and many-electron interactions. Previous studies of the partial cross
section and the photoelectron anisotropy parameter are sensitive to the electric-dipole
photoionization amplitudes. Recently, the nondipole asymmetry parameter has been calculated
and is sensitive to both electric-dipole and electric-quadrupole photoexcitation channels [1,2].
We measured over the 26–140 eV photon energy range at the SRC and combined our results
with measurements made over 80–197.5 eV at the ALS. Measurements over the 90–225 eV
region were also reported in Ref [3]. In
Asymmetry parameter γ
1
0.5
0
-0.5
HF
Xe 5s
RRPA
RPAE
-1
50 100 150 200
Photon energy (eV)
Fig. 1. Xe 5s nondipole asymmetry parameters measured at
the SRC (open circles) and ALS (closed circles) compared
with HF (dotted curve), RPAE (dashed curve), and RRPA
(solid curve) calculations.
Fig. 1, the SRC and ALS results are
compared with Hartree-Fock (HF) [1],
random-phase approximation with
exchange (RPAE) [1], and relativistic
random-phase approximation (RRPA)
[2] calculations. (The curves plotted in
Fig. 1 are based on more accurate
calculations than were originally
reported in Refs. [1,2]; see Ref. [4].)
The parameter varies rapidly near
threshold and passes through a
minimum near 35 eV. This is due to
the 5s p (dipole) amplitude passing
through a "Cooper minimum," and is
essentially a one-electron effect but is
modified by interchannel coupling with
the 5p and 4d subshells and by ionic-state satellite channels. The broad maximum near 150 eV
results mainly from interchannel coupling with the 4d subshell, which is included in the RPAE
and RRPA calculations but not HF. The small feature measured near 160 eV and predicted by
the RRPA calculation results from coupling of the 5s d (quadrupole) channels with the 4p
f quadrupole shape resonances. A full report on this study is in Ref. [4].
[1] M. Ya. Amusia et al., Phys. Rev. A 63, 052506 (2001).
[2] W. R. Johnson and K. T. Cheng, Phys. Rev. A 63, 022504 (2001).
[3] S. Ricz et al., Phys. Rev. A 67, 012712 (2003).
[4] O. Hemmers et al., Phys. Rev. Lett. 91, 053002 (2003).
*The ANL group is supported by the Chemical Sciences, Geosciences, and Biosciences Division, Office of Basic
Energy Sciences, Office of Science, U.S. Dept. of Energy, under Contract No. W-31-109-Eng-38.

NEW FEATURES IN THE PHASE DIAGRAM OF CUPRATES
Adam Kaminski
Department of Physics, University of Wales Swansea, United Kingdom
One of the most intriguing properties of the cuprates is their generic phase
diagram, where high temperature superconductivity occurs in the
proximity of a metal-insulator transition. The understanding of the various
phases and their connections is deemed to be the key to solving the
problem of high temperature superconductivity. We have used Angle Resolved
Photo Emission Spectroscopy (ARPES) to address this problem. By studying
the temperature dependence of the bilayer splitting we have found evidence of
a cross over between coherent and incoherent electron behavior - long anticipated
by a number of theoretical models. We have also shown that a
pseudogap exists on the overdoped side of the phase diagram below T c , when
the superconductivity is suppressed by application of a sufficiently high
current density. However, above certain doping, the pseudogap is
no longer observed under the superconducting dome. This may indicate existence
of a Quantum Critical Point (QCP) at a doping level between 0.2 and 0.25 holes per Cu atom.
Existence of such point could mean close relation between cuprates and
in heavy fermion compounds, where QCP is usually surrounded by dome of superconductivity.
These results are instrumental in choosing a viable theoretical model of high temperature
superconductivity.

PHOTOELECTRON SPECTROMETRY OF ATOMIC CHROMIUM IN
THE REGION OF THE 3P TO 3D GIANT RESONANCE
Scott B. Whitfield 1 , Brian Krosschell 1 , and Ralf Wehlitz 2
1 Department of Physics and Astronomy, University of Wisconsin, Eau Claire, WI 54701
2 Synchrotron Radiation Center, University of Wisconsin, Stoughton, WI 53589
Atomic Cr, by virtue of its half filled 3d and 4s subshells, [Ar]3d 5 4s 1 ( 7 S 3 ), is one of the
simplest open-shell atoms to have a partially filled d subshell. This makes detailed studies of
atomic Cr particularly attractive both theoretically and experimentally. In fact, atomic Cr has
been the object of fairly extensive experimental and theoretical investigations [1]. Nevertheless,
there is presently no experimental data of the angular distribution parameters, , of the Cr
mainlines. Only recently has there been any theoretical calculations of [2] and this for the 3d
photoelectron only. This lack of experimental data for prompted us to investigate its photon
energy dependence for both the 3d and 4s mainlines and the strongest photoelectron satellite line
in the region of the 3p 3d giant resonance. A comparison between our measured values as a
function of photon energy for the 3d mainline and theory is shown in the figure below. There is
generally good accord between experiment and theory with the exception of certain resonance
transitions which were not accounted for by theory.
We have also found strong
deviations from = 2.0 for the 4s
mainline on most of the 3p 3d
resonances, while off resonance they have
values of 2.0 as generally expected. For
half-open shubshell atoms one generally
expects s-subshell photoelectrons to have
= 2.0 independent of the incident
photon energy. Deviations from this
behavior are an indication of relativistic
effects. We will present a simple
qualitative argument for why we observe
deviations of = 2.0 for the 4s mainline
on resonance.
This work was supported by a Research Corporation College Cottrell Grant No. CC5243.
The SRC is operated under Grant No. DMR-0084402.
References:
[1] Th. Dohrmann, A. von dem Borne, A. Verweyen, B. Sonntag, M. Wedowski, K. Godehusen,
P. Zimmermann and V. Dolmatov. J. Phys. B, 29, 4641 (1996) and references therein.
[2] V. K. Dolmatov, A. S. Baltenkov, and S. T. Manson, Phys. Rev. A, 67, 062714 (2003).

SPIN-RESOLVED PES OF COMPLEX SYSTEMS
J. G. Tobin
Lawrence Livermore National Laboratory
Livermore, CA, USA
Several examples of the utilization of spin-resolved photoelectron spectroscopy to
investigate complex systems will be discussed. This will include the application of SR-PES to
possible half-metallic ferromagnets at the Advanced Light Source at Lawrence Berkeley
National Laboratory [1] and the potential of measurements at higher energies, as illustrated by
the first spin-resolved photoelectron spectroscopy results from the Advanced Photon Source at
Argonne National Laboratory [2]. The utility of the application of SR-PES to non-magnetic
systems will also be discussed [3,4], including the investigation of surface states [5] and future
potential studies of the correlated electron system -Pu. [6,7]
1. S.A. Morton, G.D. Waddill, S. Kim, I.K. Schuller, S.A. Chambers, and J.G. Tobin,
“Spin-Resolved Photoelectron Spectroscopy of Fe3O4,” Surface Science Letters 513,
L451(2002).
2. G.D. Waddill, T. Komesu, and S.A. Morton and J.G. Tobin, http://www-cms.llnl.gov/st/aps.html.
3. Ch. Roth et al, Phys. Rev. Lett. 73, 1963 (1994).
4. K. Starke et al, Phys. Rev. B 53, 10544 (1996).
5. M. Hochstrasser, J.G. Tobin, E. Rotenberg and S.D. Kevan, “Spin-Resolved
Photoemission of Surface States of W(110)-(1X1)H,” Phys. Rev. Lett. 89, 216802
(2002).
6. K.T. Moore, M.A. Wall, A.J. Schwartz, B.W. Chung, D.K. Shuh, R.K. Schulze, and J.G.
Tobin, “The Failure of Russell-Saunders Coupling in the 5f States of Plutonium”, Phys.
Rev. Lett. 90, 196404 (2003).
7. J.G. Tobin, B.W. Chung, R. K. Schulze, J. Terry, J. D. Farr, D. K. Shuh, K. Heinzelman,
E. Rotenberg, G.D. Waddill, and G. Van der Laan, “Resonant Photoemission in f-
electron Systems: Pu and Gd", Phys. Rev. B 68, 1151XX (2003).

PHOTOEMISSION STUDY OF USb AND UTe – 5f ELECTRONIC
STRUCTURE AND MAGNETISM
T. Durakiewicz 1, 2 , G. Lander 1 , C.G. Olson 3 , J.J. Joyce 1 , M. T. Butterfield 1 , E. Guziewicz 1, 4 ,
A.J. Arko 1 , J. L. Sarrao 1 , F. Wastin 4 , J. Rebizant 4 , K. Mattenberger 5 , and O. Vogt 5
1 Los Alamos National Laboratory, Los Alamos NM87545, USA; 2 Institute of Physics, UMCS
Lublin, 20-031 Poland; 3 Ames Laboratory, Iowa State University, Ames IA, USA; 4 Institute of
Physics, Polish Academy of Sciences, Warsaw, Poland; 4 European Commission, JRC, Institute
of Transuranium Elements, Postfach 2340, D-76125 Karlsruhe, Germany; 5 Laboratorium fur
Festkorperphysik, ETH, CH-8093 Zurich, Switzerland.
USb and UTe single crystal compounds were investigated by angle-resolved
photoelectron spectroscopy. Measurements were performed at the Synchrotron Radiation Center,
Stoughton, WI, using the plane grating monochromator line, with an energy resolution of 20meV
at 20eV light and an angular resolution of 1 degree.
Uranium monoantimonide is an antiferromagnet with T N =214K. USb is an unusual
monopnicitde, having a 3k magnetic ordering structure of type I, with the moments aligned
towards the (111) direction [1]. Within the first eV below E F there are at least three well resolved
peaks, A, B and C, positioned at approximately 55meV, 210meV and 610meV below E F ,
respectively. In previous work [2] peaks A and B were not resolved, due to lower energy
resolution (50meV). In our ARPES study one may notice the following: (i) all three peaks are
dispersive, with about 20meV dispersion for peak A, 50meV for peak B and about 100meV for
peak C, (ii) the maximum photoemission intensity is seen around the X point, (iii) none of the
peaks represent a band that crosses E F .
The monotelluride UTe is a ferromagnet with T C =104K of a semi-metallic character. The
-X ARPES reveals a structure within the first 1eV below E F composed of two bands, where the
broader band B might be a superposition of more than one feature. Both bands seem to be
relatively flat. Only a minor change in intensity is seen around the X point. Major changes in
photoemission intensity are seen around the FM transition, where band A crosses EF at the
transition. Since the FWHM of peak A is of the order of 200 meV, and it’s BE at low
temperatures is about -55 meV, one cannot state that an actual gap is formed below the
transition, as suggested in [3].
When compared with Np and Pu monoantimonides and monochalcogenides, a direct
correlation between the binding energy of the peak bearing most of the 5f weight in the
photoemission spectrum, magnetic moment and transition temperature may be seen within the
series. Existence of such a correlation indicates the central role of 5f electrons in establishing the
magnetic properties of these materials. Hybridization of the 5f electrons with the conduction
band is found within the series and the level of localization is shown to increase from Sb to Te.
The SRC is operated under Grant No. DMR-0084402. Work Supported by the US
Department of Energy, Office of Science.
References:
[1] G.H. Lander and P. Burlet, Physica B 215, 7 (1995).
[2] H. Kumigashira, T. Ito, A. Ashihara, H.D. Kim, H. Aoki, T. Suzuki, H. Yamgami and T.
Takhashi, Phys. Rev. B 61, 15707 (2000).
[3] B. Reihl, N. Martensson and O. Vogt, J. Appl. Phys. 53, 2008 (1982).

FIELD IONIZATION OF CH 3 I IN SUPERCRITICAL AR
C. M. Evans 1 and G. L. Findley 2
1 Department of Chemistry and Biochemistry, Queens College – CUNY,
65-30 Kissena Blvd, Flushing, NY 11367
2 Department of Chemistry, University of Louisiana at Monroe,
Monroe, LA 71209
Supercritical fluids have recently been shown to improve rates and modify product ratios
of chemical reactions, to vary chemical shifts in NMR, and to alter lifetimes and energies of
molecular vibrational states. However, the detailed nature of the molecule (i.e., dopant)/fluid
(i.e., perturber) interactions that lead to these effects is not well understood. In recent studies of
the density dependence of solvatochromic shifts of vibrational and UV-visible absorption bands,
an increase in the energy shift near the critical density along the critical isotherm of the perturber
was observed (cf. Fig. 1). In measurements of the field ionization of high-n CH 3 I Rydberg states
in supercritical argon, we observed a decrease in the shift near the critical density along the
critical isotherm (cf. Fig. 2). Such a dramatic difference in behavior is striking. The densitydependent
shift of the dopant ionization energy in dense media can be written as a sum of
contributions, = w 0 (P) + V 0 (P), where w 0 is the shift due to the average polarization of the
perturber by the ionic core, V 0 is the quasi-free electron energy in the perturbing medium and P
is the perturber number density. Our preliminary analysis suggests that while w 0 shifts in a
manner similar to the vibrational and UV-visible band shifts, V 0 does not. Thus, the difference in
behavior between the shift of high-n Rydberg states and of vibrational (or UV-visible) absorption
bands is due to the interaction of the quasi-free electron with the perturbing medium.
This work was conducted at SRC (NSF DMR-0084402) and was supported by a grant from
the Louisiana Board of Regents Support Fund (LEQSF (1997-00)-RD-A-14).
1996
0.0
1994
-0.2
line position (cm )
-1
1992
1990
1988
(eV)
-0.4
-0.6
1986
-0.8
1984
0 2 4 6 8 10 12 14 16 18
density (mol/L)
Fig. 1. Infrared absorption line peak position of the T 1u
asymmetric CO stretching mode of W(CO) 6 in CO 2 vs
CO 2 density at (!) the critical temperature of 33C and
() 50C. The lines provide a visual aid. (Modified
from R.S. Urdahl, D. J. Myers, K. D. Rector, P. H.
Davis, B. J. Cherayil and M. D. Fayer, J. Chem. Phys
107, 3747 (1997).)
-1.0
0
5
10
15
Ar
(10 21 cm -3 )
Fig. 2. Ionization potential of CH 3 I in argon
plotted as a function of argon number density Ar.
() -114C; () -118C; () various lower
temperatures other than the critical temperature;
() the critical temperature of -122C. The lines
provide a visual aid. (C. M. Evans and G. L.
Findley, to be published.)
20
25

CANADIAN SYNCHROTRON RADIATION FACILITY
Y.F. Hu, A. Jürgensen and K.H. Tan
Canadian Synchrotron Radiation Facility, Synchrotorn Radiation Center,
3731 Schneider Drive, Stoughton, WI 53589 USA
T.K. Sham
Dept. of Chemistry, the University of Western Ontario,
London, Ont. N6A 5B7 Canada
The Canadian Synchrotron Radiation Facility (CSRF) is a national research facility that is
owned and managed by NRC-CNRC (National Research Council Canada) and NSERCC
(Natural Sciences and Engineering Research Council of Canada). It is located at the Synchrotron
Radiation Center (SRC), University of Wisconsin-Madison, and is operated by the University of
Western Ontario since 1982. CSRF provides three beamlines to the Canadian user community: a
Grasshopper (20 to 250 eV), an SGM (240 to 700 eV) and a DCM (1500 to ~5000 eV). The
SGM is moving to the Canadian Light Source (CLS) in October of 2003.
These beamlines are regularly used for XANES and EXAFS analysis of solids with
simultaneous collection of the Total Electron Yield (TEY) and Fluorescence Yield (FY) signals.
This allows the determination of surface structure (TEY) and bulk structure (FY) of the sample.
Other experiments performed at CSRF beamlines include X-ray Excitation Optical
Luminescence (XEOL), Magnetic Circular Dichroism (MCD) and Photoemission Electron
Energy Microscopy (PEEM) of solids, and PhotoElectron-PhotoIon-CoIncidence (PEPICO)
spectroscopy of gases.
The research done at CSRF spans over a broad range of disciplines including: materials
science (semiconductors and nanoparticles), biology (plants and bacteria), environmental studies
(soils and solid particles from lakewater), tribology (anti-wear oil films), agriculture (manure)
and geology (rocks and minerals). Most users of the CSRF beamlines are from Canada. A few
are from New Zealand and the United States. On average, over 25 papers containing work done
at CSRF are published annually.

FUTURE PLANS AND RECENT ACCOMPLISHMENTS AT CNTECH
James W. Taylor, Franco Cerrina, Paul Nealey, Don Thielman, and Dan Malueg
Center for NanoTechnology (CNTech), 3731 Schneider Drive, Stoughton, WI 53589-3097
There have been a number of new instruments added to the facilities at CNTech over this
past year and a number of accomplishments in the research and development area that will be
highlighted in this presentation. First, the high energy beamline providing 2,750 keV (0.45 nm)
exposure radiation to the Mitsubishi Electric Company (MELCO) written diamond membrane X-
ray masks has proven the concept that removing the carbon from the mask membrane and
operating at higher energy will reduce the effects of diffraction and permit the printing of smaller
linewidth mask features. This beamline feeds the JSAL Mod 4 stepper, and it has been upgraded
to perform well at small gaps. The metrology capabilities have been upgraded with a LEO
scanning microscope with 2 nm resolution and an atomic force microscope equipped with
nanotube tips.
New etching equipment for CNTech has arrived and has been installed on campus in the
new cleanrooms of WCAM in the Engineering Centers building. These etchers will provide the
capability for etching polysilicon, a material of choice for the clear phase X-ray mask involving
the Bright Peak Enhanced X-ray Phase Mask (BPEXPM). The progress of the BPEXPM effort
will be described, and we note that the work has progressed to the point that modeling and
experiment are in agreement. The BPEXPM has been shown to produce wafer images factors of
3-5 smaller than the mask image and considerably larger gaps than utilized with proximity X-ray
lithography. CNTech is working with BAE Systems of Nashua, NH to make devices with this
technology.
Negotiations are in progress with SEMATECH to install a short section undulator on the
ring to power a new EUV exposure station operating at 13.4 nm. SEMATECH needs access to
such a station to foster the development of EUV lithography involving multi-layer masks.
Currently, CNTech operates an EUV exposure station on the U2 undulator, and recent results on
that beamline will be described.
CNTech has continued its work with new chemically-amplified resists and their
optimization for high resolution, high contrast, and high sensitivity operation. The Design of
Experiments optimization has proven to be especially useful for this effort.
We are expecting delivery of a stepper in June of 2004 from JSAL of Burlington, VT that
will push the state-of-the-art in overlay alignment. This stepper will utilize an approach that was
developed at MIT called the Interferometric Broad Band Imaging (IBBI) system.
This work is supported by DARPA Grant MDA972-01-1-0039, a DARPA/NAVAIR
grant N00421-03-1-0001, and a sub-contract with BAE Systems under NAVAIR N00421-02-C-
3029. The Synchrotron Radiation Center is supported by the National Science Foundation under
Grant DMR-0084402.

SELF-ASSEMBLY OF BLOCK COPOLYMERS ON
LITHOGRAPHICALLY DEFINED NANOPATTERNED SUBSTRATES
Paul Nealey
Center for NanoTechnology (CNTech), 3731 Schneider Drive, Stoughton, WI 53589-3097
and
Dept. of Chemical Engineering, University of Wisconsin-Madison, Madison, WI 53706
Top-down approaches to fabrication such as advanced lithographic techniques are
designed to meet severe processing constraints, but may be prohibitively capital intensive or may
not offer sufficient control at the nanoscale. Inexpensive bottom-up approaches based on selfassembling
materials such as colloidal particles and block copolymers often possess the required
nanometer resolution, but the dimensions over which the self-assembled structures are defectfree
limits potential applications. Tremendous promise exists for the development of hybrid
technologies in which self-assembling materials are integrated into existing manufacturing
processes to deliver molecular level control in parallel processes to meet exacting tolerances and
margins, and placement of the structures, including registration and overlay, with nanometer
precision. Here we demonstrate the integration of advanced lithography with the self-assembly
of thin films of block copolymer to induce the epitaxial assembly of densely packed nanoscopic
domains. The areas over which the patterns are defect free, oriented and registered with the
underlying substrate are arbitrarily large, determined by the size and quality of the
lithographically defined surface pattern rather than the inherent limitations of the self-assembly
process.

IDENTIFICATION OF SUB-MICROMETER SILICATE INCLUSIONS IN
ARCHEAN ZIRCONS WITH A X-RAY PHOTOELECTRON EMISSION
SPECTROMICROSCOPY (X-PEEM)
B. H. Frazer (1,2), G. De Stasio (1), B. Gilbert (3), A. Cavosie (4) and J. W. Valley (4)
(1) University of Wisconsin-Madison, Dept. of Physics and Synchrotron Radiation Center
(2) Institute de Physique Appliquée, Ecole Polytechnique Fédérale de Lausanne
(3) University of California-Berkeley, Earth and Planetary Science
(4) University of Wisconsin, Department of Geology and Geophysics
We recently optimized a new differential-thickness coating technique to analyze
insulating samples with X-ray PhotoElectron Emission spectroMicroscopy (X-PEEM). X-PEEM
is non-destructive, analyzes the chemical composition and crystal structure of minerals and can
spatially resolve chemical species with a resolution presently reaching 35 nm. We tested the
differential coating by analyzing a 4.4 billion-year-old zircon containing silicate inclusions. We
observed quartz inclusions smaller than 1 µm in size, that could not be analyzed with any other
non-destructive technique. We also present X-ray absorption near-edge structure (XANES)
spectroscopy of 20 silicate, alumosilicate and aluminum oxide minerals and two glasses at the
SiK and SiL 2,3 , and OK edges. The similar nearest-neighbor environments lead to similar spectral
lineshapes at each edge, but the fine-structure differences allow individual and groups of
structurally similar minerals to be distinguished. By combining spectra and their first energy
derivative from three absorption edges, we show that every mineral studied is distinguishable
with XANES. These reference spectra, assist in the interpretation of sub-micrometer inclusions
in archean zircons, studied with X-PEEM.

A
B
S
T
R
A
C
T
S

Epitaxial strain in La 2-x Sr x CuO 4 : Fermi Surface change and T c enhancement.
M. Abrecht 1* , D. Ariosa 1 , D. Cloëtta 1 , G. Margaritondo 1 , M. Onellion 2 , and D. Pavuna 1 .
1 IPMC, School of Basic Sciences, Ecole Polytechnique Fédérale de Lausanne (EPFL)
CH-1015 Lausanne, Switzerland
2 Department of Physics, University of Wisconsin-Madison, Madison, WI-53706, USA
Extended abstract
Using our dedicated Pulsed Laser Deposition (PLD) system and in-situ Angle Resolved
Photoemission Spectroscopy (ARPES) as opposed to the traditional cleaving or scraping of
samples in UHV, we measured the band dispersion of epitaxially strained La 2-x Sr x CuO 4
(0.1x0.2) thin films to investigate the links between strain induced increase in
superconducting transition temperature (T c ) and low energy electronic features. Such
measurements are the first direct probing of the electronic structure of any high T c
superconductor under epitaxial strain, and were made possible only thanks to our new approach
of sample growth at the Synchrotron Radiation Center.
We emphasize the importance of such measurements since strain has been known to increase
substantially the superconducting properties of cuprates: the critical temperature of La 2-x Sr x CuO 4
(LSCO) under epitaxial strain for example can reach 50K whereas for a non strained sample, the
T c value does not exceed 39K whatever the Sr (doping) content [Locquet].
Our APRES results on in-plane compressed films show a band dispersing along the k x reciprocal
space direction and crossing the Fermi level before the Brillouin zone boundary (figure 1), in
sharp contrast to a flat band staying well below the Fermi level for unstrained samples with equal
doping [Ino]. Our results were confirmed on various sampes with different doping values x
[Abrecht] using the Scienta analyzers of the SRC. Very surprisingly, the critical temperatures of
the strained samples are enhanced by more than 6 degrees despite a tremendous reduction of the
density of states due to the disappearance of the saddle point near the Fermi level (figure 2).
Based on a simple 2D tight binding approximation, we were able to predict the Fermi Surface
evolution with doping and strain (figure 3), a simulation that proved accurate for both Ino’s bulk
data [Ino] and our strained and unstrained film samples. Implications of our findings on possible
superconducting mechanisms in the cuprates include that the van-Hove singularity is not
essential to obtain high critical temperatures, and that T c =T c (x, ), where is a parameter related
to strain that should be included in the Superconducting phase diagram.
* Present address: National Institute of Standards and Technology, Magnetic Technology Division, 325 Broadway,
Boulder CO-80305.

Photoemission spectra, a.u.
-0.3
-0.2
0.5
0.6
K y = 0, K x / =
0.7
0.8
0.9
0.0
-0.1
Binding
Energy, eV
Figure 1: Momentum resolved photoemission data along k x of an optimally doped (x=0.15) LSCO
film under compressive strain. Note the band crossing the Fermi level for k x 0.8.
Figure 2: Dispersion of the 2-dimensional band for bulk LSCO (left), and for an in-plane
compressed film with identical doping (right). These figures were obtained by fitting experimental
data (similar to Fig 1) but along the two high-symmetry directions -X and -M (for the unstrained
sample, experimental data were taken from [Ino]). See also Fig 2 in reference attached [Abrecht].
Note the disappearance of the saddle point in the strained film, and the topological transition of
the Fermi Surface (zero energy cut) from so-called hole-like (unstrained) to electron-like (strained).
Critical temperature values were 38K (unstrained sample) and 44K (in-plane compressed sample).

1
1
0.8
0.8
0.6
0.6
0.4
0.4
0.2
0.2
Ky
0
Ky
0
-0.2
-0.2
-0.4
-0.4
-0.6
-0.6
-0.8
-0.8
-1
-1 -0.8 -0.6 -0.4 -0.2 0 0.2 0.4 0.6 0.8 1
Kx
-1
-1 -0.8 -0.6 -0.4 -0.2 0 0.2 0.4 0.6 0.8 1
Kx
Figure 3a: Calculated Fermi Surface
change with doping (band filling) of nonstrained
LSCO, assuming an unchanged
band shape, ie. identical to that of Fig 2
left. From the outside to the inside,
doping values are x = 0.05, 0.10, 0.15,
0.22, and 0.30. Note that these simulated
Fermi Surfaces are in excellent
agreement with the experimentally
measured ones by Ino et al. [Ino]
Figure 3b: Calculated Fermi Surface
change (band filling) of in-plane
compressed LSCO films assuming an
unchanged band shape, ie. identical to
that of Fig 2 right. From the outside to
the inside, doping values are x = 0.05,
0.08, 0.15, 0.2, 0.3.
References
[Loquet]: J.P. Locquet et al., Nature 394, 453 (1998)
[Ino]: A. Ino et al., PRB 65, 945041 (2002)
[Abrecht]: M. Abrecht et al., PRL 91 570021 (2003); reference is attached.

THE INITIAL AND FINAL STATE BANDS
IN BI ALONG T
Christian R. Ast 1,2 and Hartmut Höchst 1
1 Synchrotron Radiation Center, University of Wisconsin-Madison, Stoughton, WI 53589
2 Max-Planck-Institut für Festkörperforschung, Stuttgart, Germany
Determining the dispersion of an energy band in three dimensional momentum space
from angle resolved photoemission spectra requires knowledge of the final state band structure
since information about the momentum of the photoelectron is lost as it is refracted at the sample
surface. Commonly, a free electron final state model is assumed, however, at low final state
energies the bands can still be affected by the periodic potential such that the free electron model
breaks down. It has been shown from normal emission spectra of Bi(111) that for final state
energies below about 60 eV deviations from the free electron approximation can be observed [1].
In order to find the band dispersion in momentum space from photoemission spectra involving
low final state energies both initial and final state bands have to be extracted from the
photoemission spectra.
Fig. 1: Normal emission spectra of Bi(111) as a function of photon energy.
We report angle resolved photoemission spectra of Bi(111) measured at normal emission
as a function of photon energy. Changing the photon energy in this geometry samples the
Brillouin zone along the T line. The photon energy range extends from 8 eV to 100 eV
covering several Brillouin zones. From the data we have extracted the initial state bands within 3
eV binding energy as well as the final state bands up to a final state energy of 100 eV using a
phenomenological, modified free electron model that incorporates deviations from the freeelectron
dispersion. In Fig. 1 a close up of the photoemission spectra can be seen for one of the
bulk bands in Bi. The solid and dashed lines trace primary and secondary cone emission features
while the circles indicate peak positions in the spectra. The arrows labeled G1 to G3 indicate
final state gaps away from the Brillouin zone boundaries which are visible in the photoemission
spectra.

Fig. 2: Comparison of the experimental initial state bulk band structure of Bi along
the T direction with various model calculations.
Furthermore, scattering events can play a significant role in the interpretation of
photoemission spectra. They lead to various phenomena that can be observed in the
photoemission spectra. It has been shown for bismuth that scattering events induce loss features
in the 5d-core level spectra [2], which can be associated with interband transitions inside the
crystal. In the normal emission spectra we present here secondary cone emission features, which
result from transitions involving reciprocal lattice vectors not parallel to the normal emission
direction, can be observed. For these features to be observed in the normal emission spectra the
photoelectrons need to be scattered back into the normal emission direction. We show that for a
complete data analysis secondary cone emission phenomena have to be included. The presence
of secondary cone emission features in the spectra clearly shows the significance of scattering
phenomena in photoemission spectra of bismuth.
Figure 2 shows the extracted initial state bands (black lines) in comparison with a third
neighbor tight-binding calculation [3], as well as two first principle calculations [4, 5] (dotted
lines). The agreement in the dispersion is mostly qualitatively. The tight binding calculation has
difficulties reproducing the dispersion of the middle band, whereas the calculation by Gonze [4]
shows the best agreement with the experimental initial state bands.
[1] G. Jezequel, J. Thomas, and I. Pollini, Phys. Rev. B 56, 6620 (1997)
[2] C. R. Ast and H. Höchst, Phys. Rev. Lett. in press (2003).
[3] Y. Liu and R. E. Allen, Phys. Rev. B 52, 1566 (1995)
[4] X. Gonze, J.-P. Michenaud, and J.-P. Vigneron, Phys. Rev. B 41, 11827 (1990)
[5] A. B. Shick, J. B. Ketterson, D. L. Novikov, and A. J. Freeman, Phys. Rev. B 60, 15484
(1999)

TRANSITION LAYERS AT BURIED FERROMAGNETIC
INTERFACES PROBED BY SOFT-X-RAY RESONANT MAGNETIC
SCATTERING
B. Barnes 1 ; Z. Li 2 ; D. Savage 2 ; E. Wiedemann 2 ; M. Lagally 2
1 Physics, UW-Madison, Madison, WI
2
Materials Science and Engineering, UW-Madison, Madison, WI
Understanding the effect of interfaces on the magnetic properties of thin films is
critical to understanding such diverse phenomena as spin-dependent transport (e.g. giant
magnetoresistance [GMR]) and coupling between magnetic films. Interfacial morphology
for ferromagnetic [FM] materials may be characterized as a combination of chemical and
magnetic boundaries. Previous work by Kelly, et al.[1] used the diffusely scattered
component of X-ray resonant magnetic scattering (XRMS) to compare the magnetic and
chemical roughness the upper interface of 70 Co films that were either bare or Fecapped.
The chemical and magnetic upper boundaries within the Co differed in the
absence of an adjoining Fe layer, due to a transition layer of spins that do not follow
applied magnetic fields. Though the bottom interface contributed very little to the
resultant scattering, its relative contribution could not be resolved. However, by
performing specular XRMS over a wide range of incident angles, we now report a depth
profile of the magnetization within Co films 12 to 36 thick. To isolate the effect of
underlayer magnetism upon the lower transition layer, uncapped Co films were sputterdeposited
onto both Si substrates and onto ~ 8 Ni underlayers on Si. We quantify both the
upper transition layer (due to the vacuum-Co interface) and the lower transition layer, and
thus illustrate the role of magnetic underlayers in maintaining magnetic order.
[1] J.J. Kelly IV, et al. J. Appl. Phys. v.91 pp.9978-9986 (2002).
Funding provided by ONR. Funding for the Synchrotron Radiation Center provided
by NSF under Award No. DMR-0084402

TRIPLE PHOTOIONIZATION OF NEON AND ARGON NEAR
THRESHOLD
J.B. Bluett 1 , D. Luki 2 , S.B.Whitfield 3 , I.A. Sellin 4 , and R. Wehlitz 1
1 SRC, UW-Madison, 3731 Schneider Dr., Stoughton, WI 53589
2 Institute of Physics, 11001 Belgrade, Yugoslavia
3 Department of Physics and Astronomy, UW-Eau Claire, WI 54702
4 Department of Physics, University of Tennessee-Knoxville, TN 37996
The threshold behavior of the triple photoionization cross-section of neon was
investigated using monochromatized synchrotron radiation and ion time-of-flight (TOF)
spectrometry. The monochromatized photon beam ionized neon or argon atoms in the
experimental chamber. The ions created were accelerated by a pulsed electric field and
detected by a Z-stack of microchannel plates [1].
The absolute cross-section is
found to follow the Wannier
power law [2], i.e., the partial
cross-section is proportional to
the excess energy E raised to a
power , E . We obtained
an exponent of 2.20 0.05 that
has a range of validity of ca. 5eV
(green curve in Fig. 1). This
result is consistent with the
exponent of 2.162 predicted by
theory and is also consistent with
the finding of Samson and Angel
[3].
However, we did not find a secondary power law as in Ref. [3] but observed a smooth
decrease of the exponent with increasing excess energy. Nevertheless, we could
reproduce the exponent for the “second” power law as reported in [3] with an exponent of
1.89(4) (red curve) if we perfom the fit over the same energy range (5-9 eV) as in Ref [3].
Also for argon, we can confirm the Wannier power law and determined an exponent of
2.21(12) in good agreement with the theoretical prediction. However, the range of
validity is significantly shorter than for Ne, namely ca. 2 eV only.
This work was supported by NSF Grant No. 9987638. The SRC is operated under NSF
Grant No. DMR-0084402.
References:
[1] R. Wehlitz, D. Luki, C. Koncz, and I.A. Sellin, Rev. Sci. Instrum. 73, 1671 (2002).
[2] G.H. Wannier, Phy. Rev. 90, 817 (1953).
[3] J.A.R. Samson and G.C. Angel, Phys. Rev. Lett. 61 1584 (1988).

LOW-DIMENSIONAL ELECTRONS AT SILICON SURFACES
J. N. Crain 1 , J. L. McChesney 1 , Fan Zheng 1 , M. C. Gallagher 2 , P. C. Snijders 3 , M. Bissen 4 ,
C. Gundelach 4 , S. C. Erwin 5 , and F. J. Himpsel 1
1 Dept. of Physics, UW-Madison, 1150 University Ave., Madison, Wisconsin 53706
2 Dept. of Physics, Lakehead University, Thunder Bay, ON P7B-5E1 Canada
3 Dept. of NanoScience, Delft University of Technology,
Lorentzweg, 2628 CJ Delft, The Netherlands
4 Synchrotron Radiation Center, UW-Madison, 3731 Schneider Dr., Stoughton, WI 53589
5 Center for Computational Materials Science, Naval Research Laboratory,
Washington, DC 20375
Electrons become increasingly correlated as the dimensionality is reduced from 3D to
2D and 1D. Already in 2D one observes correlations between electrons and vortices in the
quantum Hall effect leading to fractional charge and statistics. Predictions for a 1D metal
anticipate a complete breakdown of the single electron concept and the separation of spin and
charge into two collective excitations, spinons and holons.
It has become possible to systematically engineer two- and one-dimensional surface
structures of metals on silicon that are metallic [1,2]. Electrons near the Fermi level are decoupled
from the substrate because there energy lies in the band gap. The metal atoms,
however, are rigidly tied to the silicon lattice in substitutional positions according to x-ray
diffraction [3] and first principles band calculations. That makes a Peierls transition to an
insulator unfavorable and creates an opportunity for observing exotic states predicted for onedimensional
metallic electrons.
Examples of two-dimensional metals are the 3x3 and 21x21 reconstructions of
Ag and Au on Si(111), which exhibit an intricate pattern of Fermi surfaces induced by the
superlattice [2]. Information about the Fourier components of the superlattice potential is
obtained from avoided band crossings.
One-dimensional atomic chains are created by growing Au and a variety of other
metals at vicinal Si(111) surfaces in the 1/5 monolayer coverage regime [1]. This appears to
be a rather universal phenomenon, and even the flat Si(111) surface breaks its three-fold
symmetry to accommodate chain structures. This wide-open territory of 1D structures is
explored in real and reciprocal space by scanning tunneling microscopy (STM) and angleresolved
photoemission. The resulting energy bands and Fermi surfaces can be tuned between
2D and 1D by increasing the chain spacing, with the intra-chain / inter-chain coupling ratio
varying from 10:1 to >70:1. Unexpected metallic bands are found, such as a pair of nearly
degenerate, half-filled bands, a quarter-filled band, and a fractional electron count of 8/3
electrons per 1x1 cell [1]. A possible explanation for the fractional electron count is
suggested, where extra Si atoms in a 2D cell “dope” the 1D chain embedded in it. This would
be analogous to the doping in HiT c materials, where a 3D cell dopes an embedded 2D plane.
References:
[1] Losio, et al., Phys. Rev. Lett. 86, 4632 (2001); Altmann et al. Phys. Rev. B 64, 035406
(2001); Crain et al., Phys Rev. Lett., in press (2003).
[2] Crain, et al., Phys. Rev. B 66, 205302 (2002).
[3] Robinson, et al., Phys. Rev. Lett. 88, 096104 (2002).

THE CANADIAN LIGHT SOURCE: A BRIGHT LIGHT SHINING
IN A COLD LANDSCAPE
J.N. Cutler
Canadian Light Source, University of Saskatchewan, Saskatoon, Saskatchewan, S7N 5C6
The Canadian Light Source (CLS), a 2.9 GeV synchrotron facility, is currently
being constructed at the University of Saskatchewan. The immense 84 m x 83 m
building is now complete; and major accelerator equipment (e.g. the booster ring) is
currently being commissioned. The facility (with at least six beamlines) will be
operational by the end of 2003.
Fifteen beamlines (with very heavy involvement from the Canadian chemistry
community) have now been approved to go forward; and proposals for two other
beamlines are being developed. Most of these beamlines and associated endstations, will
be extremely useful for research ranging from materials and environmental science to life
sciences – using infrared spectroscopy and spectromicroscopy, µ-EXAFS, single crystal
diffraction, and soft and hard x-ray XANES and EXAFS. This poster will present the
current status of the Canadian Light Source project and some insight into the future of the
facility.

SUBCELLULAR DISTRIBUTION OF
MOTEXAFIN GADOLINIUM IN TUMOR CELLS
M. J. Daniels 1 , R. J. Erhardt 1 , B. H. Frazer 1 , D. Rajesh 2 ,
S. P. Howard 2 , M. P. Mehta 2 , G. De Stasio 1
1 UW-Madison-SRC, 3731 Schneider Dr., Stoughton WI, 53589
2 Department of Human Oncology, Medical School UW-Madison, Madison WI 53792
Gadolinium Neutron Capture Therapy (GdNCT) is a brain cancer therapy at the
experimental stages. It requires that Gd target the nuclei of cancer cells, while sparing those of
healthy tissue. In our multi-year quest for the optimum Gd compound to use for this therapy, we
recently tested Motexafin gadolinium (MGd). MGd is an agent with known tumor specificity, as
revealed by MRI, proposed as a radiosensitizer. Macroscopic tumor uptake of MGd has been
well documented, but the microscopic, subcellular distribution of MGd is not well known. We
studied the subcellular distribution of MGd in two different in vitro cell lines, TB10 and U87
(both human glioblastoma cells) using the Spectromicroscope for PHotoelectron Imaging of
Nanostructures with X-rays (SPHINX) at SRC. Our extensive data analysis revealed that 86% of
the cell nuclei contained Gd. This result is promising because we previously calculated that an
effective GdNCT agent must target >90% of cell nuclei. Furthermore, this studied showed that
the concentration of Gd was highest in the cytoplasm, than the nucleus, but with longer exposure
times this nuclear Gd concentration seemed to increase.

X-RAY PHOTOELECTRON EMISSION SPECTROMICROSCOPY
REVEALS THAT POLYSACCHARIDES TEMPLATE ASSEMBLY OF
BIOGENIC NANOSCALE CRYSTAL FIBERS
G. De Stasio 1 , C.S. Chan 2 , S.A. Welch 3 , M. Girasole 4 , B.H. Frazer 1 ,
M. Nesterova 5 , L.M. Weise 1 and J.F. Banfield 2
(1) UW-Madison (2) UC-Berkeley
(3) Australian National University (4) Italian National Research Council
Neutrophilic iron oxidizing bacteria extract metabolic energy from iron oxidation in various
environments, such as groundwater seeps, streams, wetlands, the rhizosphere, and hydrothermal
vents. Their physiology is not well understood, and in particular the role of extracellular
polymers in iron oxide mineralization and possibly energy metabolism. Recent experiments with
the Spectromicroscope for PHotoelectron Imaging of Nanostructure with X-rays (SPHINX) on
precipitated Fe oxides in biofilms clarified that microbially extruded polysaccharide filaments
provide the precipitation substrate for amorphous FeOOH. Upon aging the mineralized filaments
crystallize to ferrihydrite (2-line FeOOH), with one curved pseudo-single crystal of akaganeite
(-FeOOH), at the core of each filament, of aspect ratio 1:1000:1. Structure and morphology of
this unusual and unprecedented nanoscale crystal is therefore templated by polysaccharides.
After formation of the crystal fiber, the polysaccharide structure is also altered, and C1s spectra
suggest that the COO - group is involved in the templation mechanism.

LINEAR POLARIZATION MEASUREMENTS OF THE
SYNCHROTRON RADIATION FROM A BENDING MAGNET
B. M. Dirksen 1 and K. W. McLaughlin 2
1 Dept. of Medical Physics, University of Wisconsin, Madison, WI 53713
2 Dept. of Physics and Engineering, Loras College, Dubuque, IA 52001
We have measured the linear
polarization of the ionizing radiation on the
Stainless Steel Seya beam line 021 at the
Synchrotron Radiation Center by measuring
the displacement current from a gold surface
after this radiation had reflected at a 45 o
incident angle from another gold surface. A
characteristic cos 2 () pattern was observed
upon rotating these surfaces about the
ionizing radiation propagation direction.
After normalizing to the displacement
current for the 45 o reflection surface and
accounting for the reflection coefficients of
gold surfaces [1,2], we can place a minimum
value for the linear
polarization of 97%,
independent of the ionizing
photon energy from 24 eV
down to zero order on the
beam line monochromator
grating.
Propagation
direction for
synchrotron
radiation
A
A
We would like to thank the staff and administration of the Synchrotron Radiation Center for
the opportunity and assistance in accomplishing this project. The kind assistance of Mark
Bissen, Roger Hansen, Bob Julian, Chris Moore, Mary Severson and Dan Wallace is particularly
noted.
This work is supported by NSF Grant No. 9731869. The SRC is operated under Grant No.
DMR-0084402.
References:
[1] J. A. R. Samson, Techniques of Vacuum Ultraviolet Spectroscopy (Wiley, 1967), pages 304-
305.
[2] D. W. Lynch and W. R. Hunter, "Optical Constants of Metals" in Handbook of Optical
Constants of Solids, edited by E. D. Palik (Academic Press, New York, 1985), page 286.

TEMPERATURE DEPENDENCE OF N=1 BISMUTH-BASED
HTSC AS SEEN IN ARPES
L. Dudy 1 , B. Müller 1 , A. Krapf 1 , H. Dwelk 1 , H. Höchst 2 and R. Manzke 1
1 Humboldt Universität zu Berlin 2 Synchrotron Radiation Center (SRC)
High temperature superconductivity in the cuprates mainly results from the twodimensional
electronic structure of the hole-doped CuO-planes. The maximum transition
temperature of this kind of material is dependent of the number of CuO-planes per unit-cell
and of the layers between the CuO-layers. These layers basically isolate the CuO-planes from
each other and dope holes in them. The current status of our investigations focuses on the
single-layer material Bi 2 Sr 2-x La x CuO 6+ (Bi-2201), which is available in high quality single
crystals. Substituting divalent Sr by trivalent La varies the hole concentration of our samples
almost continuously. Because of the low transition temperature this material provides in
addition the advantage of investigating the normal state with extremely small temperature
broadening. For photoemission measurements Bi-2201 also benefits of the absence of bilayer
splitting. This effect occurs by the interaction of electrons between narrow CuO-planes
as e.g. observed in Bi 2 Sr 2 CaCu 2 O 8+ (Bi-2212).
In the past we presented high-resolution photoemission results performed at SRC
which below a certain temperature show along the direction of the CuO-bonds a
characteristic two-peak structure [1]. It has been shown that the low energy sharp peak is
strongly dependent of the applied polarization of the incident light (Fig.1a) [2]. To going
further it seems like the structure isn’t visible in each M-direction (Fig. 1b). Another
remarkable observation is that this structure is not only seen in the superconducting regime
but also persists above the transition temperature and vanishes at higher temperatures
(Fig.1c). The comparison of temperature dependence with a pseudo-1d-system [3] points to a
pseudo-1d effect. In our interpretation these features are associated with one-dimensionality
of the electronic structure leading to spin-charge separation [4]. The necessary condition for
this state is the formation of an asymmetric electronic density, a phenomenon called stripes
[5]. The present contribution follows this interpretation but profits from the raise of data
collected at the SRC in order to explain the phase diagram more precisely and identifies the
vanishing of the one-dimensionality with the closing of the pseudogap [6]. Recent results [7]
of the universality of the pseudogap temperature T* for every CuO-plane in every cuprate
will also be tried to be discussed.

Fig.1: Photoemission spectra of optimally doped Bi 2 Sr 2-x La x CuO 6+ (x=0.40, T c =29 K) in the normal state at the
M-point of the Brillouin zone. Polarization dependence (a): Shown are two polarization geometries, where the
sample was kept fixed and the electrical field vector E of the linearly polarized synchrotron radiation has been
turned by 90°. T=35K, h=34eV, and E=30meV [2]. 90°-asymmetry (b): Shown are two spectra taken at
otherwise identical conditions at the two equivalent M-points (,0) and (0,). T=35K, h=22eV, and
E=16meV. Temperature dependence of weakly overdoped (BiPb) 2 Sr 2-x La x CuO 6+ (x=0.15, T c =25K) (c):
Shown are spectra taken near M at (0.75,0) for two temperatures, at T=10K where the double structure is very
pronounced and at T=90K it has vanished. The thick dotted curves in all three panels are the difference spectra.
References:
[1] C. Janowitz, R. Müller, L. Dudy, A. Krapf, R. Manzke, C. Ast, H. Höchst, Europhysics
Letters 60 (2002) 615
[2] R. Manzke, R. Müller, C. Janowitz, M. Schneider, A. Krapf, H. Dwelk, Phys. Rev. B
(Rapid Commun.) 63 (2001) 100504
[3] R. Claessen et al., Phys. Rev. Lett. 88, 096402 (2002)
[4] J. Voit, Euro. Phys. J. B 5 (1998) 505
[5] for an introduction see J. Orenstein, A.J. Millis, SCIENCE 288 (2000) 468 and references
therein
[6] for a review about the Pseudogap see T. Timusk und B. Statt Rep. Prog. Phys. 62, 61
(1999)
[7] T. Honma, P.H. Hor, H.H. Hsieh, M. Tanimoto, cond-mat/0309597, 2003

UPGRADING THE SAMPLE MANIPULATOR OF THE SCIENTA-
2002 USER SYSTEM WITH AN ADDITIONAL ANGULAR DEGREE
OF FREEDOM
Chad T. Gundelach, Mike V. Fisher, Sergey Gorovikov and Hartmut Höchst
Synchrotron Radiation Center, University of Wisconsin-Madison,
3731 Schneider Drive, Stoughton, WI 53589
The SRC user community has access to two state of the art photoemission
systems equipped with a 200 mm Scienta spherical electron analyzer. Both analyzers are
capable of high energy and angular resolution. In the multidetection mode, the lens
system has an angular dispersion of ~1mm/degree enabling the simultaneous detection of
about 10 degrees along the entrance slit of the analyzer with an angular resolution of ~0.2
degree. By mounting the analyzer so that the angular dispersion plane is either horizontal
or vertical, the 10-degree angular sampling window was used by various user groups to
sample data in the azimuthal- or polar-direction relative to the sample normal. Depending
on Users’ preferences, the orientation of the SES-200 system was switched several times
during the past few years. Remounting the analyzer is a very elaborate and timeconsuming
process. Frequent orientation changes not only increase the down time of the
system but also can also seriously jeopardize the spectrometer performance or damage
the fragile multi-channel plate detector.
To minimize the needs for orientation changes on the SES-2002 system, we
upgraded the sample manipulator with an additional degree of angular rotation. The
poster describes the design of the new cryogenic sample manipulator and reports first test
measurements utilizing the azimuthal and polar dispersion direction to map a large twodimensional
section of the Brillouin zone. The design efforts were governed by space
limitations, which led to coupling some mechanical components to the cold head’s outer
cryo-shield without significantly diminishing the thermal performance. The polar
rotation axis is established by capturing a ball in detents on both sides of the lower inner
stage using set-screws from the outer stage. An additional benefit of supporting the lower
inner stage with the outer stage is the improved mechanical and thermal positional
stability. As the inner stage is heated, the thermal expansion of the upper inner stage is
absorbed by bendable cooling straps while the sample itself remains in the fixed outer
shield position. The mechanism for actuating the polar sample angle is located beneath
the lower inner stage. It is based on a worm gear system consisting of a segment of a
titanium gear that is driven by a silicon bronze worm. The self-locking characteristic of
the worm gear mechanism prevents unintentional rotation. Two 0.012” thick by 2 “ wide
OFHC copper straps provide thermal coupling to the inner cryo-stage and allow the
sample holder to rotate by ±30 degree around the polar axis. Measurements verified that
the temperature drop along the flexible Cu bands is less than 1K.
Two GaAlAs diode temperature sensors are mounted to the cold finger. The
permanent stationary diode (PSD) is mounted on the upper inner stage near the heater,
while the permanent moving diode (PMD) is mounted on the lower inner stage just above
the sample area. The heater and diodes allow for closed loop control of the sample
temperature using a Lakeshore temperature controller.

The sample manipulator has a cool
down time of six hours. This long time
constant is a result of the large thermal mass
of the cold finger. The cryo head itself
reaches a minimum temperature of ~10K in
less than an hour under no load conditions.
Temperature measurements with a calibrated
GaAlAs diode mounted on the Ti-sample
slug indicate a minimum sample temperature
of ~18.5K. Another test investigated the
impact radiative heating had on the minimum
temperature, the difference between having
the sample area shielded and unshielded was
~ 4K.
Extrapolating the temperature versus
heater power curve for the two permanent
diodes to 10K provides an estimate of the
heat load at the inner stage to be ~0.5 W.
This heat loss includes all sources of head
load on the inner stage such as radiative heat
and heat leak from the outer to inner stage
(titanium balls and worm gear interface).
By engaging the worm shaft with a
non-magnetic ball driver, the polar angle can
be actuated while the sample is in measuring
position at an azimuthal angle of ~0 degree.
The ball driver is attached to a retractable
externally mounted rotary-linear feed
through. The additional thermal losses
imposed by the ball driver are minimal.
While engaged for longer time periods, the
temperature increase at the sample was only
~0.2K.
The functionality of the polar angle
scan and the reproducibility of the
mechanism were also tested in the
photoemission chamber under UHV
Figure 1 - Fermi Surface of BiSb alloy single
crystal measured at a photon energy of 18 eV
conditions. The improved thermal positional stability allowed photoemission
measurements to be taken on a small sample (< 1 mm diameter) as it was heated from 18
to 280 K without the need to reposition the sample. The figure on the right shows a twodimensional
photoemission intensity map of a Bi0.86Sb0.14 crystal near the Fermi
energy which was measured at 50K utilizing the newly added polar angular axis.
Acknowledgements
The Synchrotron Radiation Center (SRC) is funded by the National Science Foundation
(NSF) under Grant No. DMR-0884402.

ANGLE-RESOLVED PHOTOEMISSION OF UAsSe AND USb 2
E. Guziewicz 1 , T. Durakiewicz 1 , M.T. Butterfield 1 , C.G. Olson 2 , J.J. Joyce 1 , A.J. Arko 1 ,
J.L. Sarrao 1 , A. Wojakowski 3 , T. Cichorek 3,4
1 Los Alamos National Laboratory, Los Alamos, New Mexico, 87545
2 Ames Laboratory, Iowa State University, Ames IA, USA
3 Institute of Low Temperature and Structure Research, Polish Academy of Sciences,
Wroclaw, Poland
4 Max Planck Institute for Chemical Physics of Solids, D-01187 Dresden, Germany
We have performed ARPES study on single crystals of UAsSe and USb 2 . Both compounds
have tetragonal layered crystal structures and order magnetically along the c axis at low
temperature. UAsSe shows ferromagnetic behavior below 116K, and USb 2 is an
antiferromagnet below 203K.
Magnetic behavior gives
evidence for localization of the
U5f states. However, the
enhanced Sommerfeld
coefficients (41 mJ/mol·K 2 for
UAsSe and 26 mJ/mol·K 2
Figure 1: Angle-resolved normal photoemission spectra of USb 2
and UAsSe showing 3D character of these compounds.
for
USb 2 ) indicate some degree of
hybridization between the U5f
and conduction band electrons.
We have investigated this
problem of correlation between
the U5f electrons and their
hybridization with the
conduction band using ARPES.
Photoemission spectra were
taken on the PGM beamline at
the SRC in Wisconsin with an
overall energy resolution for
the lowest photon energies
(h=20 eV) of 24 meV. Both
uranium compounds display a similar electronic structure within 100 meV of the Fermi
edge, where a very narrow 5f character peak is found. The intensity of this peak does not
follow a simple photoionization cross-section dependence for the U5f electrons, indicating
a considerable degree of hybridization with the conduction band. In both UAsSe and USb 2
we have found a dispersion of the peak near the Fermi edge of about 10 meV and 20 meV,
respectively, which is additional evidence of hybridization. The dispersion in normal
incidence spectra (Fig. 1) provides evidence that neither UAsSe nor USb 2 have purely 2D
electronic structure and thus require treatment as 3D or quasi-2D materials. The narrow
bands in these U-based magnetic materials are reminiscent of the band magnetism found in

Cr and Fe but for these U systems the band widths and dispersions are two orders of
magnitude smaller.
Work Supported by the US Department of Energy, Office of Science. The SRC is
operated under Grant No. DMR-0084402.

Hidden One Dimensionality and Non-Fermi Liquid ARPES Lineshapes
of the Electronic Structure of η-Mo 4 O 11
G. –H. Gweon 1* , S. –K. Mo 1 , J. W. Allen 1 , H. Höchst 2 , J. L. Sarrao 3 , and Z. Fisk 3
1. Randall Laboratory of Physics, University of Michigan, Ann Arbor, MI 48109
2. Synchrotron Radiation Center, University of Wisconsin, Stoughton, WI 53589
3. National High Magnetic Field Lab., Florida State University, Tallahassee, FL 32306
η-Mo 4 O 11 is a layered metal that undergoes two charge density wave (CDW) transitions at 109 K
and 30 K, and is unique in showing a bulk quantum Hall effect [1]. Research so far indicates that
this material has a “hidden one-dimensional” (hidden-1d) Fermi surface (FS) in the normal state
(T > 109 K), whose nesting property drives the 109 K CDW formation [2]. Here, we directly
confirm this picture by angle resolved photoemission spectroscopy (ARPES). Figure 1 shows the
Fermi energy intensity map measured at T=150K and with hν=17eV at the 4m-NIM line of the
Synchrotron Radiation Center. The geometry of the FS is in good general agreement with that of
the band calculation, and can be seen as two vertical lines of hidden-1d FS coming from chains
along the crystal b axis and double oblique hidden 1-d lines coming from chains along the crystal
(b±c) axes. The latter are characterized by a single nesting vector Q CDW , similar to the situation
of other 2-d hidden-1d materials like NaMo 6 O 17 and KMo 6 O 17 [3]. Fig 2 shows the temperature
dependent change of the valence band spectrum at point A and B respectively. We have observed
that there is a small gap opening of size ~15meV only at the point A accompanied with a change
in the line shape, while at the point B, which is a part of the remnant FS that is not nested by
Q CDW, the spectrum does not show any change as the temperature decreases. Even more
interesting, this material also shows the same ARPES line shape anomalies and lack of Fermi
edge in the angle integrated spectrum, that we have identified in other low dimensional metals
and that are most easily rationalized within an electron fractionalization scenario that includes
for the quasi-2d systems the idea of a “melted holon” part of the lineshape, arising from disorder
[4]. This lineshape is neatly confined to the electronic bandwidth but is essentially featureless in
energy and k. It is best seen in a region of k-space where all dispersing peaks lie above the
Fermi energy. Fig. 3 shows the “melted holon” lineshape of η-Mo 4 O 11 obtained at such a point
in k-space, along the yellow line marked in the Fig. 1. Disorder that could be responsible is
known in this material [5]. More detailed studies on the lineshapes and also of the 30 K CDW
transition are in progress.
The work at University of Michigan is supported by the US NSF grant No. DMR-0302825. The
SRC is supported by the US NSF grant No. DMR-00-84402.
References
[1] S. Hill et al., Phys. Rev. B 58, 10778 (1998).
[2] E. Canadell et al., Inorganic Chemistry 28, 1466 (1989)
[3] G. –H. Gweon et al., Phys. Rev. B 55, R14453 (1997).
* current address: Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, CA 94720

[4] G. –H. Gweon, J. W. Allen, and J. D. Denlinger, cond-mat/0303122.
[5] Mallet et al, Phys. Rev. B 63, 165428 (2001).
k (Å -1 )
0 y 0.2 0.4
A
B
Z
Γ
Q CDW1
M
Y
-0.5 0 0.5
k x (Å -1 )
Figure 1. Normal state Fermi energy
intensitiy map of η-Mo4O11. White arrow
shows the nesting vector for T=109K CDW
transition.
Intensity (arb. units)
(a)
110 K
50 K
-0.2 -0.1 0 0.1
(b)
-0.2 -0.1 0 0.1
E-E F (eV)
-1 -0.5 0
E-E F
Figure 3. “Melted holon”
lineshape at the Y point of the
k-space.
Figure 2. Temperature dependent
change of the valence band spectrum at
point A and B respectively.

THE FERMI SURFACES OF THIN Sb(111) FILMS
Hartmut Höchst and Christian R. Ast
Synchrotron Radiation Center, University of Wisconsin-Madison
3731 Schneider Drive, Stoughton, WI, 53589
The unique electronic properties of the group-V elements Sb and Bi, their small
Fermi energy combined with highly anisotropic electron and hole masses and carrier
concentrations several orders of magnitude lower than in normal metals makes them
prime candidates for potential thermoelectric converters. Devices based on nano-scale
structures of Sb and Bi or alloys thereof are among those with the highest conversion
efficiency.[1,2]
The rhombohedral (A7) crystal structure of the group V-elements causes a
negative band gap. The conduction band minimum at the L-point is lower than the
valence band maxima, which occur at the H-point for Sb and at the T-point for Bi. As a
result, the Fermi surfaces (FS) consist of six pockets centered at the H-points or of two
half-pockets centered at the T-points. Band structure calculations using different
theoretical approaches agree in some basic overall Fermi surface features.[3-6].The
calculated dimensions of the Fermi surface however have been far from experimental
results based on magnetotransport and resonance measurements. These data were
historically the most accurate even though indirect sources to judge the quality of the
various theoretical approaches. More recently, photoemission spectroscopy (PES) was
recognized to be a potentially useful additional tool to investigate the electronic
properties near the FS. Compared to the classical FS measurements, PES has the
advantage that information can be gathered from very small samples, at elevated
temperatures and from materials, which exhibit strong impurity, compositional or
structurally related scattering effects otherwise detrimental to most classical resonance
based FS measurements.
We report the first photoemission based FS data of Sb. Combining ARPES with
the tuneability of synchrotron radiation allows determining the parallel components of the
Fermi momentum k x and k y . Using a simple final state model provides also access to the
perpendicular component k enables us to separate the three dimensional hole- pocket
typical for bulk Sb from additional FS features which are of 2D-nature and most likely
related to the presence of a Sb bilayer on the (111)-surface. Compared to Bi[7-9], which
has extremely small bulk hole-pockets, preventing a detailed k-mapping due to
experimental limitations in the momentum resolution, the carrier concentration in Sb is
~200 times larger and thus opening up the possibility of tracing the contours of the bulk
hole-FS. The location and cross section of the hole pocket in the mirror plane compares
well with theoretical predictions based upon pseudopotential calculations by Falicov and
Lin [3] while other more recent and advanced model calculations [4-6] seem not to
comply with our data.
Acknowledgements
The Synchrotron Radiation Center (SRC) is funded by the National Science Foundation
(NSF) under Grant No. DMR-0884402.

References
[1] S. Cho, Y. Kim, A. Di Venere, et al., Journal of Vacuum Science & technology A:
Vacuum Surfaces and Films 17, 2987 (1999).
[2] X. Sun, Z. Zhang, and M. S. Dresselhaus, Applied . Physics Letters 74, 4005 (1999).
[3] L. M. Falicov and P. J. Lin, Physical Review 141, 562 (1966).
[4] J. Rose and R. Schuchardt, Physica Status Solidi (b) 117, 213 (1983).
[5] Y. Liu and R. E. Allen, Physical Review B 52, 1566 (1995).
[6] X. Gonze, J. P. Michenaud, and J. P. Vigneron, Physical Review B 41, 11827 (1990).
[7] C. R. Ast and H. Höchst, Physical Review Letters 77, 177602 (2001)
[8] C. R. Ast and H. Höchst, Physical Review B 66, 125103 (2002).
[9] C.R. Ast and H. Höchst, Physical Review Letters 90, 016403 (2003)
Fig.1 : Fermi level intensity map I(k || ) of Sb(111) measured at hv=25 eV
Fig.2: Fermi level intensity map I(k ,k || ) of Sb(111). The perpendicular electron
momentum k was changed by scanning the photon energy from 14-28 eV.

MOMENTUM DEPENDENT LOW ENERGY LOSSES IN CORE
LEVEL PHOTOEMISSION SPECTRA OF POORLY CONDUCTING
METALS?
Hartmut Höchst and Christian R. Ast
Synchrotron Radiation Center, University of Wisconsin-Madison
3731 Schneider Drive, Stoughton, WI, 53589
The availability of high-quality samples having low impurity levels and good
structural quality combined with instrumental improvements in synchrotron radiation
beam lines and electron energy analyzers of high energy resolution led recently to
photoemission core-level spectra exhibiting additional features which were previously
not seen. Photoemission line-shape changes or multiple core-level components can occur
through surface modifications, crystal-field splitting, vibrational contributions and
excitations of electrons or phonons. [1] The theory of core-level photoemission and
aspects of intrinsic and extrinsic excitations associated with the photo-hole, or
photoelectron, were recently restated in a series of papers by Hedin and coworkers.[2]
The relative strength of low energy excitations accompanying the “main line”
photoemission spectrum is directly related to the dc resistivity and can be quite
significant in materials of poor conductivity such as small-gap superconductors and
semimetals.[3]
We report angle resolved core-level photoemission spectra of the semimetals Sb
and Bi where we observe a multiple peak structure separated by ~170-300 meV towards
higher energy from the main 4d and 5d components, respectively.[4,5] Utilizing photons
ranging from 30-150 eV, angular scans along the k-direction normal to the (111) surface
and k || scans along high symmetry directions of the surface Brillouin-zone (SBZ), we find
dispersion in the split-off components commensurate with the bulk and surface Brillouinzone
periodicity. Additionally, the peak width and intensity of the split-off peak oscillates
between final state symmetry points.
From the wealth of accumulated information, we dismiss an earlier claim by
Patthey et al. assigning the additional feature in the Bi 5d spectra to a surface- shifted
component.[6] Since the d 5/2 and d 3/2 components show the same features symmetry
arguments rule out crystal-field effects as the source of the observed peak splitting. The
data can be explained by a k-dependent loss function consisting of several characteristic
direct and indirect low energy interband transitions excited in various parts of the bulk
Brillouin zone.
Acknowledgements
The Synchrotron Radiation Center (SRC) is funded by the National Science Foundation
(NSF) under Grant No. DMR-0884402.
References
[1] J. N. Andersen, T. Balasubramanian, C.-O. Almbladh, et al., Physical Review Letters
86, 4398 (2001).
[2] L. Hedin and J. D. Lee, Physical Review B 64, 115109 (2001).

[3] D. L. Mills, Physical Review B 62, 11197 (2000).
[4] H. Höchst, and C.R. Ast,, Journal of Electron Spectr. and Relat. Phenomena, (in
press) 2003
[5] C. R. Ast and H. Höchst, Physical Review Letter, in press (2003).
[6] F. Patthey, W. D. Schneider, and H. Micklitz, Physical Review B 49, 11293 (1994).
Fig. 1: Energy difference E 1 (filled dots) and relative peak intensity I 1 /I 0 (open dots) of the Bi 5d 5/2
component measured at h=60 eV as a function of parallel momentum along and .
Fig. 2: Fermi level region of the projected bulk band structure of Bi(111). Arrows indicate indirect (I) and
direct (D) interband transitions related to the loss features observed by LEELS.

THE P(1s) AND P(2p) XAFS SPECTRA OF ELEMENTAL
PHOSPHORUS, THEORY AND EXPERIMENT
Astrid Jürgensen
Canadian Synchrotron Radiation Facility, Synchrotron Radiation Center,
3731 Schneider Drive, Stoughton, WI, USA 53589-3097
X-ray absorption spectroscopy was used to study the local structure and chemical bonding of
elemental phosphorus. Three allotropes of this element exist in the solid state. Crystalline black-
P, a semiconducting material with an orthorhombic puckered layer structure, is the most stable
allotrope. White-P, the least stable allotrope, is composed of tetrahedral P 4 molecules. At room
temperature it is a plastic crystal. Its structure is similar to -Mn with the P 4 molecules in the
positions of the Mn atoms. The most common allotrope is the amorphous red-P. Like white-P it
is composed of P 4 molecules. In the gas phase tetrahedral P 4 molecules are stable up to ~ 800 ºC.
At higher temperatures they decompose into P 2 molecules that have a shorter P-P bond length
and, like N 2 , a formal triple bond.
Theoretical P(1s) and P(2p) XAFS spectra of gaseous and solid state phosphorus were
calculated by ab initio FEFF and GSCF3 methods. These were compared and the spectral
features were related to structural and electronic properties of the different allotropes of
elemental phosphorus. The calculation results were then used to explain the features observed in
the experimental P(1s) and P(2p) spectra of red-P, which were obtained at the DCM and
Grasshopper beamlines of CSRF, respectively. They were measured simultaneously by total
electron yield (TEY) and fluorescence yield (FY) with the incident photon beam at normal
incidence to the sample surface.
The results of this study were presented at the XAFS 12 conference, held in Malmö, Sweden in
June of 2003. A paper has been submitted to Physica Scripta to be published in the conference
proceedings. A temperature dependent P(1s) EXAFS study of red-P is in progress to determine
the Debye-Waller factor (the mean square deviation of the interatomic distance) of the first
coordination shell in red-P.
0.1
0.05
0
-0.05
-0.1
3 6 9 12 15
P4 molecule
theory
0 1 2 3 4 5 6
0.35
P4 molecule
0.28
theory
0.21
0.14
0.07
(k)
0.1
0.05
0
-0.05
-0.1
0.1
0.05
0
-0.05
-0.1
white-P
theory
black-P
theory
FT(k 3 (k)) (Å -4 )
0
0.28
0.21
0.14
0.07
0
0.28
0.21
0.14
0.07
white-P
theory
black-P
theory
0.1
0.05
0
-0.05
red-P
experiment
0
0.12
0.09
0.06
red-P
experiment
-0.1
0.03
3 6 9 12 15
k (Å -1 )
0
0 1 2 3 4 5 6
R (Å)
The experimental P(1s) (top) and P(2p)
(bottom) XANES spectra of red-P
The P(1s) EXAFS spectrum (left) and its Fourier Transform (right). The first
peak in the FT represents the first coordination shell with an interatomic
distance of 2.212 Å.

CHARACTERIZATION OF SULPHATE INTERACTIONS WITH
HEMATITE MINERALS USING XANES
T.Kotzer 1 , J.Cutler 1 , A.Pratt 2 , J.Dutrizac 2
1 Canadian Light Source, University of Saskatchewan, Saskatoon, Canada
2 Natural Resources Canada - CANMET, Ottawa, Canada
Sulphur bearing hematite is a product of some novel hydrometallurgical sphalerite
treatments. Leaching tests aimed at investigating the stability of the hematitic leach residue have
shown that only a fraction of the sulphur present is removed. In this study sulphur bearing
hematites were leached in a variety of media and examined using XANES Sulphur K-edge and
L-edge spectroscopy at the Canadian Synchrotron Radiation Facility, SRC-Madison, WI, to
address questions regarding the chemical environment, oxidation state and physical distribution
(surficial versus intercrystalline) of the sulphur within the hematite minerals. XANES S K-edge
FY and TEY and L-edge TEY spectra indicate that the sulphur predominantly occurs as sulphate
having a formal oxidation state of S 6+ and is largely distributed within the hematite matrix at
concentrations between approximately 0.04 and 4.7 %. The XANES S K- and L-edge absorption
spectra have also been used to assess the effectiveness of leach treatments employing HNO 3 and
NH 4 OH solutions for the removal of sulphate from the hematite minerals. Here, the spectra
indicate that a 0.05M HNO 3 solution was largely ineffective at removal of surficial and
intercrystalline sulphate whereas 1 to 4M NH 4 OH leach solutions appear to have variably
removed sulphate from the uppermost regions (5 to 30 nm depth) of the hematite minerals.
Overall integration of the XANES S K-edge and L-edge TEY and FY spectra provides both
unique information regarding the distribution of sulphate within the hematite matrix and a means
to evaluate the effectiveness of leach processes used to remove sulphate from hematite minerals.

Exploratory Experiments: Photodetachment of Negative Ions
by Energetic Photons
Thomas Kvale 1 , Song Cheng 1 , David Seely 2 , and Jeffrey Thompson 3
1
The University of Toledo, Toledo, OH 43606
2 Albion College, Albion, MI 49224
3
The University of Nevada, Reno, NV 89557
Abstract
One of the current investigations in Atomic Physics is the electron-electron interaction in
atoms by placing atoms in "exotic" states. A unique opportunity exists to perform a series of
experiments which will probe this interaction by examining continuum states in various atomic
species by photodetaching negative ions. Synchrotron radiation is useful in providing a
continuously tunable source of photons over the energy range of interest. Various theories [1, 2]
predict the photodetachment cross sections are rich in features (both minima and resonances) in this
photon energy range. This situation makes these studies ideally suited for providing stringent tests
of our current understanding of atomic structure. The specific experiments listed in this abstract are
representative of the types of experiments possible and are only the first in an extended series of
experiments that are currently of great interest in atomic physics.
The first series of experiments that are proposed will probe the photon energy region from
4eV to 20 eV in a variety of relatively light elements. Gribakin, et al. [1] predicted the
photodetachment cross sections for the outer np and nearby ns subshells of C - 2p 34 S, Si - 3p 34 S, and
Ge - 4p 34 S. The np photodetachment cross sections have minima around 5eV above the negative ion
ground states and then rise to maxima at around 8 eV before gradually falling again. The minima
have widths of order of 0.5 eV, whereas the maxima have widths of several eV. By contrast, most
of the predicted [2] resonances
in Be - ( 4 P o , 4 D o , and 4 S o ) have
widths of order of 10-50 meV.
These proposed experiments
complement previous
photodetachment experiments of
the authors at lower photon
energies. With an estimated
photon flux of 10 12 photon/s, an
ion current of 100 nA, and the
predicted photodetachment cross
sections, we expect a
photoelectron current of
approximately 10-1000 e - /s. An
apparatus (PHOTO-2) has been
constructed for conducting this
series of photodetachment
experiments (see Figure).
Briefly, it consists of: a 0 - 50kV negative ion accelerator; a dodecapole chamber for merging the
ion and photon beams; an interaction chamber of approximately 30 cm long; and data acquisition
chamber. Photodetached electrons are energy analyzed by a hemispherical energy analyzer located

in the data acquisition chamber. The various residual ion, neutral, and photon beams exit through
an aperture in the outer hemisphere of the analyzer and are detected by a Faraday cup detector. The
interaction region has magnetic field coils to null the earth's magnetic field throughout this region.
The predicted continuum state structure (energy locations, widths, and magnitudes) are very
sensitive to specific atomic structure theory approximations, and experimental measurements such
as the ones currently proposed will provide stringent tests of our understanding of the electronelectron
and electron-nucleus interactions that occur in atoms and ions.
References
[1] G.F. Gribakin, A.A. Gribakina, B.V. Gul'tsev, and V.K. Ivanov, J. Phys. B: At., Mol., Opt.
Phys. 25, 1757 (1992).
[2] Jose' Luis Sanz-Vicario and Eva Lindroth, Phys. Rev. A 68, 012702 (2003).
[3] D. Calabrese, A.M. Covington, D. Carpenter, J.S. Thompson, T.J. Kvale, and R. Collier, J.
Phys. B: At., Mol., Opt. Phys. 30, 4791 (1997).
[4] A.M. Covington, D. Calabrese, W.W. Williams, J.S. Thompson, and T.J. Kvale, Phys. Rev.
A 56, 4746 (1997).
[5] W.W. Williams, D.L. Carpenter, A.M. Covington, J.S. Thompson, T.J. Kvale, and D.G.
Seely, Phys. Rev. A 58, 3582 (1998).

CHEMOMECHANICAL PROPERTIES OF ANTIWEAR FILMS
USING X-RAY ABSORPTION MICROSCOPY AND
NANOINDENTATION TECHNIQUES
Mark A. Nicholls 1 , G. Michael Bancroft 1 , Peter R. Norton 1 *, Masoud Kasrai 1 , Gelsomina
De Stasio 2 , Bradley H. Frazer 2 , and Lisa M. Wiese 3
1 Department of Chemistry, University of Western Ontario,
London, Ontario, Canada N6A 2B7
2 Department of Physics, University of Wisconsin-Madison, Madison, WI 53706, USA
3 Syncrotron Radiation Center, Univ. of Wisconsin-Madison, Stoughton, WI 53589, USA
ABSTRACT
The first chemomechanical comparison between an antiwear film formed from a solution
containing zinc dialkyl-dithiophophates (ZDDPs) to a solution containing ZDDP plus a
detergent (ZDDPdet) has been performed. X-ray absorption near edge structure
(XANES) analysis has shown a difference in the type of polyphosphate, between each
film. The ZDDPdet film has been found
to contain short-chain polyphosphates
throughout and contain a large amount of
CaCO 3 . X-ray photoelectron emission
microscopy (X-PEEM) has provided
detailed spatially resolved
microchemistry of the films. The large
Intensity (arb. units)
[A]
[B]
[C]
[D]
[E]
[F]
1
2
s'
3
b
a
c
s 1
unreacted
ZDDP
Zn 10
P 18
O 55
Ca 3
(PO 4
) 2
ZDDP + Det.
X-PEEM
long-chain
internal model*
shorter-chain
internal model*
map-ave.
long-chain
pads in the ZDDP antiwear film have
[G]
map-ave.
shorter-chain
long-chain polyphosphates at the surface
[H]
and shorter-chain polyphosphates are
130 140 150 160
Photon Energy (eV)
found in the lower lying regions. The

spatially resolved chemistry of the ZDDPdet film was found to be short-chain calcium
phosphate throughout.
Fiducial marks allowed for
the re-location of the same
areas with an imaging
nanoindenter. This allowed
the nanoscale mechanical
properties, of selected
antiwear pads, to be
measured on the same length scale. The indentation modulus of the ZDDP antiwear pads
were found to be heterogeneous, ~120 GPa at the center and ~90 GPa at the edges. The
ZDDPdet antiwear pads were found to be more uniform and have a similar indentation
modulus of ~90 GPa. A theory explaining this measured similarity, which is based on the
probing depths of all techniques used, sheds new insight into the structure and
mechanical response of ZDDP antiwear films.

ELECTRONIC PROPERTIES OF MN-SILICIDE ON SI(111)
J. J. Paggel, K. Schwinge, G. Ctistis, U. Deffke, and P. Fumagalli
Institut für Experimentalphysik, Freie Universität Berlin, Germany
T. Miller and T.-C. Chiang
Department of Physics, University of Illinois at Urbana-Champaign, IL
and
Frederick-Seitz Materials Research Laboratory, University of Illinois at Urbana-Champaign, IL
The electron spin as new degree of freedom in electronics is widely discussed. One
central problem is spin-injection into the semiconductor material, i.e. the transfer of the spinpolarization
from the magnetic electrode into the semiconductor. It is generally believed that
structural disorder at the interface will lower the injection efficiency. In order to achieve high
spin-polarization in the semiconductor, epitaxial, magnetic films on semiconductors are therefore
sought after.
Mn – in its conventional antiferromagnetic -phase – might be a promising candidate for
magnetic films on silicon. Its fcc-phase is lattice matched to Si. There is even a large probability
for Mn to be ferromagnetic at RT in this phase. Growing Mn-films on Si(111) yields epitaxial
films with six-fold symmetry. Auger electron spectroscopy indicates a large Si-content of the
films, maybe even a Si surface layer. RHEED and STM indicate closed films of good quality.
The nature of these films could not be revealed using our laboratory experiments. Photoelectron
spectroscopy experiments, reported here, identify the film as metallic Mn-silicide. The bonding
character between Mn and Si is largely covalent. The Si2p core-level from the silicide is very
simple and shows a striking similarity to the core-level of the famous Si(111)-(77)
reconstruction, turning the interest from potential application of the films to basic research, as the
electronic properties of the Si(111)-(77) are still under debate. The Si(111)-(77) reconstruction
shows at least two nearly dispersionless surface states, associated with adatoms, which are also
identified as origin for the prominent surface core-level of the Si(111)-(77) reconstruction. The
Si2p core-level from the silicide shows a similar surface component, such that an adatom surface
state was expected. The latter has not been found yet.
This work was funded by the Deutsche Forschungsgemeinschaft through SFB 290 and
grant Pa661/5-1, the U.S. National Science Foundation (grant DMR-02-03003), the U.S.
Department of Energy, Division of Materials Sciences (grant DEFG02-91ER45439), and the
Petroleum Research Fund, administered by the American Chemical Society. The Synchrotron
Radiation Center is supported by the National Science Foundation under grant DMR-00-84402.

THE RELATIONSHIP BETWEEN PHOSPHATE SPECIATION IN SOILS
AND BIOSOLIDS/MANURE MANAGEMENT PRACTICES: A P K-EDGE
XANES SPECTROSCOPIC STUDY
Derek Peak,Gurpal Toor, and James T Sims
1 Dept. of Soil Science, 51 Campus Dr, Univ. of Saskatchewan. Saskatoon SK S7N 5A8
2 Dept Plant and Soil Sciences, Univ. Delaware. 149 Townsend Hall Newark DE 19717
The long-term application of animal manures and biosolids has resulted in serious
environmental issues in many locations throughout the world. For example, the state of
Delaware has a large amount of farmland characterized as having “excessive P levels” due to
heavy application of poultry waste for the last three decades. These soils serve as a significant
source for phosphate movement into waters, including the Chesapeake Bay. Elevated phosphate
levels in natural waters are a serious concern because it is typically the limiting nutrient for algae
and other photosynthetic organisms. Increased phosphate can therefore result in algal blooms
and ultimately fish kills and eutrophication.
The tendency of phosphorus to move from a soil to surface waters is highly dependent
upon its chemical form. In soils, phosphate has a tendency to form insoluble metal phosphate
solids and to form strong sorption complexes with iron and aluminum oxides. These reactions
result in phosphate typically being held very strongly by soils. In biosolids and manures,
however, high levels of soluble phosphate and readily degradable organic phosphates are found
along with more stable organic phosphates and calcium phosphate minerals. To attempt to
reduce the environmental risk of manure applications, scientists have proposed that (a) the
manures be chemically amended prior to application to reduce P availability or (b) the diet of the
animals be modified to reduce P in manures. The presented research will perform direct
chemical samples from a variety of animal types, diets, and chemical amendments using P K-
Edge XANES spectroscopy coupled with linear combination fitting. This allows us to directly
assess the success of different strategies to reduce manage phosphorus.
We found that changes in animal diet do indeed play a large role in the resulting
phosphate speciation. Adding supplemental P often served to increase the fraction of calcium
phosphate minerals present. Take for example the samples in Figure 1. The DM01 sample on
the left is a dairy manure sample from an animal with 29%P in its diet. The sample on the right
is a dairy manure sample from an animal fed 58% P. There is a marked increase in calcium
phosphate precipitation in the higher P diets, which can affect the solubility of P compared to
organic and aqueous forms. XANES has similarly been useful in determining the chemistry of
phosphate in manures amended with aluminum coagulants.
This research was supported by an NSERC Discovery grant and the Saskatchewan
Synchrotron Institute.

Figure 1. Comparison of phosphate speciation in dairy manures from cattle with different diets.
Sample DM01 is from an animal with a low P diet while DM41 is from an animal with a diet
high in P.

PHOTOEMISSION STUDIES OF QUANTUM WELL SYSTEMS WITH
VICINAL INTERFACES
D. Ricci, T. Miller, and T.-C. Chiang
Department of Physics, University of Illinois at Urbana-Champaign, 1110 West Green Street,
Urbana, Illinois 61801-3080
Frederick Seitz Materials Research Laboratory, University of Illinois at Urbana-Champaign,
104 South Goodwin Avenue, Urbana, Illinois 61801-2902
The electronic structures of thin metallic films on semiconductor surfaces have been
shown to be profoundly influenced by the films’ interfaces with the substrate and with the
vacuum. As seen using synchrotron-based angle-resolved photoemission spectroscopy, wellordered
systems grown on low-index faces may exhibit discrete electronic spectra characteristic
of quantum wells [1]. In turn, the quantized electronic structure has been observed to impact
various physical properties of the film [2]. Vicinal surfaces possess periodic arrangements of
steps which influence the growth and development of adsorbate structures [3], and thus may
produce systems with electronic properties that differ from those formed with substrates oriented
along a high symmetry axis [4]. Currently, we are probing the surface and quantum well states
arising in Ag/vicinal Si(111) and Ag/vicinal Si(001) systems, with an eye towards developing an
understanding of their electronic and physical properties. In this regard, comparison to the
existing results from the simpler on-axis systems should prove useful.
This work is supported by the U.S. Department of Energy, Division of Materials Sciences
(grant DEFG02-91ER45439). We acknowledge the Petroleum Research Fund, administered by
the American Chemical Society, and the U.S. National Science Foundation (grant DMR-02-
03003), for partial support of the synchrotron beamline operation and the central facilities of the
Frederick Seitz Materials Research Laboratory. The Synchrotron Radiation Center of the
University of Wisconsin-Madison is supported by the U.S. National Science Foundation (grant
DMR-00-84402.).
References:
[1] M. Upton, T. Miller, and T.-C. Chiang, Phys. Rev. B (in press); J. J. Paggel, T. Miller, and
T.-C. Chiang, Science 283, 1709 (1999); T.-C. Chiang, Surf. Sci. Rep. 39, 181 (2000), and
references therein.
[2] J. J. Paggel, C. M. Wei, M. Y. Chou, D.-A. Luh, T. Miller, and T.-C. Chiang, Phys. Rev. B66
233403 (2002); D.-A. Luh, T. Miller, J. J. Paggel, and T.-C. Chiang, Phys. Rev. Lett. 88,
256802 (2002); D.-A. Luh, T. Miller, J. J. Paggel, M. Y. Chou, and T.-C. Chiang, Science,
292 1131 (2001).
[3] E. Hoque, A. Petkova, M. Henzler, Surf. Sci. 515, 312 (2002)
[4] A.P. Shapiro, T. Miller, and T.-C. Chiang, Phys. Rev. B, 38, 1779 (1988)

GROWTH OF THIN FILMS ON RECONSTRUCTED SURFACES:
AG ON AU/SI(111)- 3 3
S. –J. Tang, T. Miller, and T.-C. Chiang
Department of Physics, University of Illinois at Urbana-Champaign, 1110 West Green Street,
Urbana, Illinois 61801-3080
Frederick Seitz Materials Research Laboratory, University of Illinois at Urbana-Champaign,
104 South Goodwin Avenue, Urbana, Illinois 61801-2902
Both for fundamental studies and for potential applications, it is oftentimes desireable to
be able to grow uniform films in a layer-by-layer fashion on a substrate of different material. The
interface with the substrate is an important factor controlling the nature of film growth.
Generally, epitaxial growth of thin films is facilitated by a lattice-matched starting substrate, as
there is a tendency for the substrate to serve as a template for further crystalline growth of the
film. In typical cases there exists lattice mismatch which must be accommodated by strain or by
the development of crystal imperfections in the substrate, film, or at the interface; consequently it
may be more difficult to achieve layer-by-layer growth in these systems. Similar problems may
be caused by reconstructions of the substrate surface, which may be quite complex. In these
cases, it may happen that the presence of a third species at the interface can facilitate a desired
growth pattern.
Ag films grown on the Si (111) surface provide examples of these issues. The
equilibrium (111) Si surface has the well-known, but complicated, (7x7) reconstruction. Ag
and Si both have fcc as their basic lattice but have large lattice mismatch with each other ( Si: a=
5.43 Å, Ag: a= 4.09 Å). Depending on growth conditions, Ag on this surface can form flat or
three-dimensional islands, or strained epitaxial layers. In the current work, we use Au to produce
a commensurate Au/Si(111)- 3 3 reconstructed surface as a seed layer before depositing Ag
films. This has the effect of simplifying the surface reconstruction as well as modifying its
chemical properties [1]. Subsequent growth of Ag films of various coverages was carried out at
-165C, and the films were annealed to RT. The electronic structure of the Ag thin film was
probed by angle resolved photoemission using the high-resolution low energy synchrotron beam
provided by U1-NIM beamline at SRC.
Figure 1 shows a series of energy distribution curves at normal emission from Ag films
on Au/Si - 3 3 at coverages ranging from 6 to 22 monolayers (ML). Each spectrum shows a
series of discrete peaks representing the states of the quantum well formed by the thin metallic
film. As is evident, the quantum well states peaks become narrower and shift to lower binding
energies as the Ag film coverage increases. This coverage dependent behavior of the quantum
well states can be simply explained through the phase accumulation model. The appearance of
the intense and sharp Ag surface state near Fermi level is significant as it not only reflects good
crystallinity of the film but also the important role of the intermediate 3 3 seed layer in
reducing the strain in the Ag film. This is because in films grown without the seed layer, the
strain due to the Ag/Si lattice mismatch is known to significantly shift the initial state energy of

Ag surface state such that it moves above the Fermi level and becomes depopulated and
significantly less intense [2].
Figure 2 shows the in-plane dispersion of the quantum well states and the surface state
along the - K direction for a 22 ML thick Ag film. The bottom of the Ag surface state band is
26 meV above the Fermi level. A fit
Figure1
Figure2
7.5
hv=22eV
Ag on Au/Si- root3
0.0
Ag 22Ml Au/Si
n=1
7.0
-0.2
Photoemission Intensity (arb.units)
6.5
6.0
5.5
Ag ML
22
19
16
14
12
Initial state energy (eV)
-0.4
-0.6
-0.8
-1.0
n=2
n=3
5.0
10
8
-1.2
n=4
-3 -2 -1 0
Initial state energy (eV)
6
-1.4
-0.3 -0.2 -0.1 0.0 0.1 0.2 0.3
k || (A -1 )
to the data (solid curve) reveals the effective mass m*/m of the surface state band to be 0.404
which is very close to the value 0.397 measured by F. Reinert et al [3] from the (111) surface of
bulk Ag. The dispersions of the quantum well states (crosses) can be compared with those of Ag
bulk bands calculated at constant k (triangles) [4]. The match between the measurement and
calculation is good for the quantum-well states with quantum numbers n from n = 2 to n = 4. For
the quantum-well state with n = 1, the dispersion is significantly less than that of the other
quantum well states and corresponding calculated bulk value. We note that the deeper quantumwell
states overlap the bulk bands in the substrate and so are really resonances; for such states
the reflection phase shift at the interface is relatively slowly-varying and so the dispersions in
Fig. 2 are approximately at constant k . In contrast, the energy of the n = 1 state is within the
energy gap of the substrate, where the interface phase shift is rapidly varying. In this case, the
dispersion in Fig. 2 includes an implicit variation in k so that the curvature may not reflect the
true effective mass. Further analysis of the dispersions and effective masses of quantum well
states from different other coverages will be done.
This work is supported by the U.S. National Science Foundation (grant DMR-02-03003).
We acknowledge the Petroleum Research Fund, administered by the American Chemical
Society, and the U.S. Department of Energy, Division of Materials Sciences (grant DEFG02-
91ER45439), for partial support of the synchrotron beamline operation and the central facilities
of the Frederick Seitz Materials Research Laboratory. The Synchrotron Radiation Center of the

University of Wisconsin-Madison is supported by the U.S. National Science Foundation (grant
DMR-00-84402.).
References:
1. H. M. Zhang, K. Sakamoto, and R. I. G. Uhrberg, Phys. Rev. B64, 245421 (2001).
2. G. Neuhold and K. Horn, Phys. Rev. Lett. 78, 1327 (1997).
3. F. Reinert, G. Nicolay, S. Schmidt, D. Ehm, and S. Hüfner, Phys. Rev. B63, 115415
(2001).
4. N. V. Smith and L. F. Matheiss, Phys. Rev. B 9, 1341 (1974); N. V. Smith, Phys. Rev. B
9, 1365 (1974)

HIGH-RESOLUTION STUDY OF THE LITHIUM INNER-SHELL
RESONANCES
R. Wehlitz 1 , J.B. Bluett 1 , and S.B.Whitfield 2
1 SRC, UW-Madison, 3731 Schneider Dr., Stoughton, WI 53589
2 Department of Physics and Astronomy, UW-Eau Claire, WI 54702
The resonance region of lithium (58 – 81 eV) was investigated using monochromatized
synchrotron radiation and ion time-of-flight (TOF) spectrometry. The photon beam of
the PGM undulator beam line passed through the experimental chamber containing
vaporized lithium atoms. The lithium ions created were accelerated by a pulsed electric
field into the TOF flight tube and detected by a Z-stack of microchannel plates [1].
We have observed the autoionizing resonances to higher principal quantum numbers than
in previous experiments [2,3]. Depending on the energy region we have used an energy
resolution of 10 meV and 4.5 meV with step sizes as small as 0.5 meV.
Several spectra were
taken over short
energy intervals as
indicated by the
different colors of the
composed spectrum
shown in Fig. 1. All
spectra were
normalized with
respect to the photon
flux and background
corrected. The fit
results along with the
data of other authors
will be presented for
the various Rydberg
series on the poster.
This work was supported by NSF Grant No. 9987638. The SRC is operated under NSF
Grant No. DMR-0084402.
References:
[1] R. Wehlitz, D. Luki, C. Koncz, and I.A. Sellin, Rev. Sci. Instrum. 73, 1671 (2002).
[2] G. Mehlman, J.W. Cooper and E.B. Saloman, Phy. Rev. A 25, 2113 (1982).
[3] L.M. Kiernan et al., J. Phys. B 29, L181 (1996).

RESONANCE PARAMETERS OF AUTOIONIZING Be 2pnl STATES
R. Wehlitz 1 , D. Luki 2 , and J.B. Bluett 1
1 SRC, UW-Madison, 3731 Schneider Dr., Stoughton, WI 53589
2 Institute of Physics, 11001 Belgrade, Serbia and Montenegro
While photoionization of helium has been studied thoroughly, beryllium (1s 2 2s 2 ), the
next helium-like atom in the periodic table, has been investigated only marginally by
comparison. Double excitations in the Be valence-shell region have been studied
experimentally as well as theoretically in the past. In these experiments [1,2] vacuum
sparks were used to photo-excite and –ionize Be atoms and absorption spectra were
recorded on high-sensitive film.
In general, for atomic photoexcitation resonances above the first ionization limit,
autoionization becomes possible by interaction with one or more single-ionization
continua. This leads to an
asymmetric resonance profile in the
single-ionization cross section. A
theoretical description of this process
was introduced by Fano [3] and
refined later by Shore and Starace.
Since autoionization is a
consequence of electron correlation,
a measurement of the resonance
profile for comparison with theory
can provide important information
towards our understanding of how
electron correlations affect a simple
system. We will present our
autoionization-profile measurements
of the Be 2pns (n=3-8) and 2pnd (n=3-5) double excitations [4]. Since the 1s electrons do
not actively participate in the autoionization process, Be appears to be a system only
slightly more complicated than He. However it is very different from He insofar as the
series of autoionization resonances starts immediately above the first ionization threshold
(see Fig. 1). Another difference to He is that the Be 2pns resonances are much broader
due to a strong coupling to a rather weak continuum.
This work was supported by NSF Grant No. 9987638. The SRC is operated under NSF
Grant No. DMR-0084402.
References:
[1] G. Mehlman-Balloffet and J.M. Esteva, Astrophys. J. 157, 945 (1969).
[2] J.M. Esteva, G. Mehlman-Balloffet, and J. Romand, J. Quant. Spectroc. Radiat.
Transfer 12, 1291 (1972).
[3] U. Fano, Phys. Rev. 124, 1866 (1961).
[4] R. Wehlitz, D. Lukic, and J.B. Bluett, Phys. Rev. A, in press (2003).

RELATIVE PARTIAL CROSS SECTIONS AND ANGULAR
DISTRIBUTION PARAMETERS OF THE
LI 1S2S( 3,1 S) MAIN AND 1S2P( 3,1 P) CONJUGATE SHAKE-UP LINES IN
THE REGION OF THE 1S3LN'L' AUTOIONIZING RESONANCES
Scott B. Whitfield 1 and Ralf Wehlitz 2
1 Department of Physics and Astronomy, University of Wisconsin, Eau Claire, WI 54701
2 Synchrotron Radiation Center, University of Wisconsin, Stoughton, WI 53589
Atomic Li is the simplest open-subshell atom, and is therefore an ideal candidate for
detailed experimental and theoretical studies. Despite the extensive experimental work which has
been carried out on atomic Li, there is only one rather old measurement [1] of the 1s2s( 1,3 S) main
and 1s2p( 1,3 P) conjugate shake-up photolines in the region of the strong 1s3ln'l autoionizing
resonances. We will present recent measurements of both the absolute partial cross sections, ,
and the angular distribution parameters, , of these photoelectron lines in this resonance region.
Our high resolution constant-ionic state spectra completely separate the dynamic behavior of all
four photolines allowing a detailed comparison to a state-of-the-art R-matrix calculation [2]. The
strong variations of both and of these lines across the 1s3ln'l autoionizing resonances are in
generally excellent agreement with theory. This is illustrated in the figures above for the partial
cross section of the 1s2s( 3 S) mainline and the 1s2s( 3 P) conjugate shakeup line.
This work was supported by a Research Corporation College Cottrell Grant No. CC5243.
The SRC is operated under Grant No. DMR-0084402.
References:
[1] T.A. Ferrett, D.W. Lindle, P.A. Heimann, W.D. Brewer, U. Becker, H.G. Kerhoff, and D. A.
Shirley, Phys. Rev. A, 36, 3172 (1987).
[2] L. Vo Ky, P. Faucher, A. Hibbert, J.M. Li, Y.Z. Qu, J. Yan, J.C. Chang, and F. Bely-Dubau,
Phys. Rev. A, 57, 1045 (1998).

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Christian Ast
Max-Planck Institute fhr Festk`rperforschung
Heisenbergstra8e 1
70569 Stuttgart
Germany
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Los Alamos National Laboratory
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SRC Users’ Group Meeting
October 25, 2003
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Queens College – CUNY
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Department of Physics
University of Wisconsin-Madison
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Center for NanoTechnology
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Saskatchewan University
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NOTES