Scientific Opportunities with Synchrotron Radiation for Nanoscience

Scientific Opportunities with
Synchrotron Radiation for
Nano-Science
Nano Science
Zahid Hussain
Scientific Support Group, Leader
Advanced Light Source
Lawrence Berkeley National Laboratory

Outline
Why and How?
• What we need to learn about nano systems ?
• What kind of tools are necessary ?
• What facilities are available at the
synchrotron (ALS) ?
• What facilities need to be developed ?
Understanding complex nano-phenomena nano phenomena require advanced
tools
Close proximity essential for efficiency and timely results

Opportunities for nanoscience with soft x-rays
@ ALS
1. Spectroscopy (In-Situ, real time)
Absorption/Emission Spectroscopy (photon-in photon-out, bulk
sensitivity, mag/elctric field)
Photoemission Spectroscopy (photon-in electron-out, surface
sensitivity, upto 10 torr)
2. Microscopy (sometime combined with spectroscopy)
Scanning Transmission Microscope (STXM; Res ~25nm)
Transmission Imaging Microscope (XM1/2; Res ~15 nm)
Photoemission electron microscope (PEEMII/III; Res ~5-50nm)
Lensless diffractive imaging (3D images, Res ~5-10nm)
3. Scattering
Resonant Scattering (~100-1000 times higher cross section)
Resonant Inelastic Scattering (res ~3-4meV @ Mn/Cu 3p edges)
Coherent (dynamic) Scattering (time resolution msec to nanosec)
Small and Wide Angle Scattering (SAXS/WAXS, soft x-rays
provide unique capabilities)

Spectroscopy
Quantum confinement (properties different
than constituents)
Chemical Bonding (chemical reactivity)
Electronic Structure (understanding complexity)

Quantum-confinement effects and particleparticle
interactions in Ge & Si nanocrystals
Absorption Spectra
Conduction band shift vs particle size
Atomic force microscope
sub-ML multilayer
• Ge nanoparticles condensed out of the gas-phase
• Particle-size determined post-situ by AFM
• Blue-shift of Ge L-edge correlated with
decreasing cluster size
•Stronger CB confinement effects observed in Ge
than in Si nanoparticles.
C. Bostedt et al. APL 84, 4056 (2004) — LLNL PRT
C. Bostedt et al. APL 85, 5334 (2004)

Surface Reconstructions in Nanodiamonds
Emission Absorption
Need of theory
Core – Diamond; Surface – buckyballs
C 147 (≈1.2 nm) C 275 (≈1.4 nm)
• Pre-edge Carbon K-edge structures observed in
diamond clusters different from bulk
diamond.
• Fullerene-like reconstructions determined at
surfaces of diamond clusters by ab initio
calculations compatible with pre-edge XAS
J.-Y. Raty, G. Galli, C. Bostedt, T.W. Buuren & L.J. Terminello,
PRL 90, 4056 (2003) — LLNL PRT

High resolution C1s Photoelectron Spectra of
hydrocarbon
C 1s photoelectron spectra of
propyne and two model compounds
ethyne and ethane measured.
Unambiguous assignment of peaks in
propyne spectrum is made possible
by characteristic vibrational
structure and ab initio theory.
Shift of the methyl (CH3) peak in
propyne relative to ethane is due
to the electronegativity of the
ethyne (HCºC) group.
Previous C 1s spectrum of propyne
measured with a lab source is
indicated by the dashed line
From BL 10.0 (AMO, ALS)
Thomas et al, PRL
Ambient pressure photoemissiom

Microscopy
STXM: Microbial Polymer Templates for Iron Oxyhydroxides
Spectra taken
above C K edge
Natural filaments
Fe (~ 25 nm) with a polymer
as core (~5nm)
1 µm
C.S. Chan, G. De Stasio, S.A. Welch, M. Girasole, B.H. Frazer, M.V. Nesterova, S.
Fakra, J.F. Banfield, "Microbial Polysaccharides Template Assembly of
Nanocrystal Fibers“, Science 303, 1656-1658 (2004). LBNL-55375
Synthetic filaments (Fe-Alginate)
1 µm
Look like natural filaments!
STXM confirmed that the natural polymers are
mostly polysaccharides with some proteins (by doing spectroscopy)
spectroscopy

WHAT IS COHERENT X-RAY DIFFRACTION IMAGING
(CXDI) OR LENSLESS IMAGING ?
ALS undulator beam
• Spatially and
temporally
coherent
• Monochromatic
• 0.5-5 keV energy
Life-science or
materials-science
sample
• Alignment
• Viewing
• Rotation
• Cryoprotection
• CCD detector
• Directly records
diffraction pattern
• To get a 3D image:
- record a tilt series of diffraction patterns
- insert the resulting Fourier amplitudes into a 3D
Fourier space
- use a 3D phase retrieval algorithm to get their
phases
- get an image by Fourier inversion (“true” 3D imaging)

SEM image of 3D
pyramid test object
Object mounting on
silicon nitride membrane
Lensless Imaging:
TEST IMAGES IN 3D AND 2D
Pyramid 3D
test object
• Test object of 50 nm
gold balls
• Individual gold balls
resolved
• Estimated resolution
20 nm
• 130 views -65 to +65°
• Exposure time 10 hours
• X-ray energy = 750 eV
• Object width: about
2µm
• Reconstruction on a
Macintosh G5 in about
10 hours
• Reconstructed image of
freeze-dried dwarf yeast
A = nucleus; B = vacuole; C =
cell wall
• X-ray energy = 520 eV
• Estimated resolution
30 nm
• Exposure = 45 sec
1 µm
Chapman/Howells/Spence et al - ALS Kirz/Jacobsen/Elser/Sayre et al -ALS

Resolution (nm)
3D MICROSCOPES: RESOLUTION AND
SAMPLE–THICKNESS LIMITS
1000
100
10
1
0.1
GOOD RESOLUTION BUT
SAMPLE SIZE IS LIMITED
Single
particl
Room
temp
TEM
Cryo
TEM
GOOD SAMPLE SIZE BUT
RESOLUTION IS LIMITED
10 100 1000 10000
Sample thickness (nm)
Zone plate
soft x-ray
Optical
confocal
Inorganic
Organic
Lensless Imaging
RESOLUTION AND
SAMPLE SIZE BOTH GOOD

Unique features of scattering
in the soft x-ray region.
Soft x-ray resonances bring
new contrast mechanisms:
- molecular bond sensitivity
- elemental sensitivity
Extremely sensitive to small
sample volumes
- cross section ∝ λ 3
- ideal for nanoscience
- coherent power ∝ λ 2
Low q scattering at higher
angles:
- wide range structure
in 3mm –1nm
- “incoherent” & “coherent”
Unique capabilities for
spectroscopy
microscopy
time-resolved dynamic
studies
Spectro-microscopy of nano
materials
Inhomogenities of
correlated systems
(charge/orbital order)

Porous low-K dielectric films via templating process
porogen in matrix
after porogen removal
Lower limit to pore size?
Processing effects?
Mitchel, Kortright et al (unpublished)
OD
Intensity (arb. units)
NEXAFS C K-edge
Matrix
Porogen
280 285 290 295 300
Photon Energy (eV)
5
4
3
2
1
Scattering at 2θ=6 deg
0
280 285 290 295 300
Photon Energy (eV)

Scattering pre- and post-processing to remove porogen phase
particles.
For large porogens, R pore = R porogen.
For smallest porogen, Rpore > Rporogen. Matrix not rigid enough to sustain
smallest pores.

Coherent soft-Xray Scattering –
Dynamical Studies !!
Soft x-rays: - More coherent flux -Scales like λ 2 X brigtness
- High sensitivity for 3d metals: Resonant 2p-3d transition-
- Dynamical studies: Time resolution: > ms - 5ns) limited by
time correlator
Speckle-diffraction Pattern
through a Co:Pt film.
major loop
minor loop
Coherent Soft X-ray Magnetic Scattering End Station
• Applied field to 0.52 T of arbitrary orientation
• ‘Continuous’ scattering angle from 0 o to ~ 165 o
• Functional prototype for higher field device

Resistivity (ohm-cm)
Colossal Magnetoresistance (CMR) Effect
10 0
10 -1
10 -2
negative
magneto-
resistance
Novel Electronic Phases
La 1.2 Sr 1.8 Mn 2 O 7
H=0T
H=1T
H=2T
H=3T
H=5T
H=7T
Temperature (K)
Susceptibility (emu/mol)
Ferro
Para
0 100 200 300 0 100 200 300
Temperature (K)
CO : Charge Order (Stripes)
FI : Ferromagnetic Insulator
AFI : Antiferro. Insulator
CAF : Canted AFM Insulator
CMR : Colossal MagnetoResis.
O Large drop of resistivity
upon relatively small
magnetic fields
O Para Ferromagnetism
O Most dramatic on the
insulating phase (short range
orbital order)

Manganites Exhibit Interplay of Charge,
Spin, lattice and Orbital degrees of freedom
Interacting degrees of
freedom (complex electron
systems)
spin
charge
lattice
orbital
Competition among many Energy
and Length scales
Determine the physics of these systems

Nanoscale electronic disorder in Correlated Systems (STM)
∆
65meV
25meV
Differential Conductance (nS)
1.8
1.6
1.4
1.2
1.0
0.8
0.6
0.4
0.2
15nm
0.0
-150 -100 -50 0 50 100 150
Sample Bias (mV)
Spatial distribution of energy gap (∆)
in Bi2212 (High Tc materials)
600nm
Metal-Insulator transitions in the
CMR material La Ca MnO 3
Energy scale: ~10meV
Length scale: 2 - 1000nm
Ch. Renner et al, Nature, 416, 518 (2002)

Energy scales of various excitations
3 eV
1 eV
100
meV
0
X
Mott Gap,
C-T Gap
dd excitations,
Orbital Waves
Optical Phonons,
Magnons,
Local Spin-flips
Superconducting gap
Superconducting gap: ~ 1-10meV
Optical Phonons: ~ 40 - 70 meV
Magnons: ~ 10 meV - 40 meV
Orbital fluctuations (originated
from optically forbidden d-d
excitations): ~ 100 meV-
1.5 eV
Soft x-ray resonances (3p -> 3d) provide
a very sensitive channels of excitations
MERLIN (

Spectroscopies of Correlated Electrons
Techniques of choice:
1. Angle resolved phtotemission (ARPES) :
Single-particle spectrum A(k,ω)
2. Inelastic Neutron Scattering (INS) :
(neutrons carry magnetic moment)
Spin fluctuation spectrum S(q,ω)
3. Inelastic x-ray scattering (IXS) :
New info on the Charge Channel : N(q,ω)
This extra experimental info can help understand
correlated systems

hω 1 ,k 1 ,ε 1
Photon-in
Resonant Inelastic soft X-ray Scattering
(Raman Spectroscopy with finite q)
energy
conduction band
d
valence band
p
core level
Energy loss: ω=ω 2 -ω 1
Momentum transfer: q=k 2 -k 1
Resonance: ω 1 ~ ω edge
Why???
Can Can be applied in the presence of
magnetic/electric field
Bulk Bulk sensitive probe for studying unoccupied
electronic states
hω2 ,k2 ,ε2 Photon-out Optically Optically forbidden d-d excitation
Finite Finite q transfer allows to study indirect Mott
gap
Couples Couples to charge density directly (Neutrons
couples to spin).
Energy Energy Resolution not limited by the core
hole lifetime: achieve k BT BT resolution

meV Resolution VLS Spectrograph
Optical Design
Ray Traces
• Calculated/measured Resolution
3 meV (high efficiency)
• Overall length = 2 meters.
• Spectrograph for Merlin beamline
(completion end of 2006)
• Early experiments on bl 12
(starting in July, 2005)
200 µm
hν = 49eV ± 5meV

Momentum-Resolved Soft X-ray Inelastic
Scattering
#1 (5 o~35o)
#1
#2 (35 o~65o)
#2 #3 #4
-15o
15
0o
o
#3 (65 o~95o)
#4 (95 o~125o)
By combining the rotation of chamber and
5 mounting ports, one is able to perform momentum-resolved
RIXS; need Resolving Power ~ 100,000 – QERLIN !!
#5
#5 (125 o~155o)
ARPES
10
5
0
-5
-10
#3
#2
-5
#5
#4
#1
0
(0,0)
5
(π,0)
(π,π)

Spatial and temporal frequency sensitivities
of various techniques
Coherent
scattering

Concluding remarks
o In situ (real conditions) studies. Photon-in photon-out studies,
Ambient pressure photoemission.
o Single nanoparticle imaging and spectroscopy. STXM
o Lensless Imaging: Bulk 3D images, resolution ~ 2 λ
(inorganic ~ 2nm, Organic ~ 5nm (radiation limit)
think of combining with atomic resolution protein
Crystallography.
o Dynamic coherent scattering. (ms – 5 ns, limited by time
correlator).
o Soft x-ray scattering: Provide new contrast mechanism for
imaging. Imaging with spectroscopy.

Acknowledgement
o Inelastic Scattering: Yi-De Chuang, Jinghua Guo; Jonathan
Denlinger, (LBNL, ALS), Eric Guillikson, Phil Batson (LBNL)
o Lensless Imaging: Janos Kirtz, Malcolm Howells(LBNL, ALS)
o Nanoscience characterisation: Franz Himpsel (univ of Wisconsin),
Lou Terminello (LLNL)
o scattering: Jeff Kortright (LBNL), Mitchel (Dow chemical),
Ade (NCU)
o Coherent Scattering: Steve Kevan (univ of Oregon)

Transmission (%)
100
80
60
40
20
0
detecto
r
200
C 1s (46%)
O 1s (66%)
400 600
Energy (eV)
100nm Si 3 N 4, ~4 µl liquid volume, 66% transmission
@O1s, vacuum pressure < 1 x 10 -9 Torr
Liquid Cell - Static
grating
SR
Fe 2p (82%)
C_100nm; SiC_100nm
Si_100nm; SiN_100nm
Al_100nm
800
slit
1000
Si 3N 4
O-ring
o Ligand-stabilized Co nanoparticles
o Ligand material: Oleic Acid,
C18H34O2 [CH3 (CH2 ) 7CH:CH(CH2 ) 7CO2H] liquid
o Solvent Solution: Dichlorobenzene, C 6 H 4 Cl 2
o Size (Measured using TEM): 3, 4, 5, 6, 9 nm

In-situ analysis of Co nanoclusters in solution
3d 8 L
3d 7
∆
2p 5 3d 8 L
∆+U-Q ≈ ∆
2p 5 3d 7
o Ligand-stabilized Co nanoparticles
o Ligand material: Oleic Acid, C 18 H 34 O 2 [CH 3 (CH 2 ) 7 CH:CH(CH 2 ) 7 CO 2 H]
o Solvent Solution: Dichlorobenzene, C 6 H 4 Cl 2
o Size (Measured using TEM): 3 nm, 4 nm, 5 nm, 6 nm, 9 nm
Molecular Foundry (P. Alivisatos & M. Salmeron) & ALS (J. Guo)
CT
CT
d-d
I d-d ~ N bulk/N surface

X-Y
Nanoscience: Electronic Structure
Determination - Techniques of choice
Requirements ?
σ∗
π∗
hν
X + −Y −
“in situ, real time” studies of:
• Valence orbital (bonding, energy gap)
• Core level (charge transfer,
elemental/chemical specificity)
How ?
•Unoccupied bands:
Absorption Spectroscopy
•Occupied bands:
Emission Spectroscopy and
Photoelectron Spectroscopy
•Orientation of molecules on surfaces:
Polarization dependence studies
Requires close coupling between theory and experiment

Resonant Inelastic soft X-ray Scattering
Calculation based on photon energy of Brillouin zone size which can be covered by this
650eV and 3.85 Å lattice constant spectrometer
10
#1 (5 o ~35 o )
#2 (35 o ~65 o )
-15 o
0o 15o #3 (65 o ~95 o )
#4 (95 o ~125 o )
#5 (125 o ~155 o )
Five spectrometers with 30 o rotations can cover
most of the Brillouin zone
momentum transfer ∆q
Å -1
0.60
0.55
0.50
0.45
0.40
0.35
0.30
0.25
0.20
0.15
0.10
0.05
5
0
-5
-10
-5
0
(0,0)
-15 -10 -5 0 5 10 15
chamber rotation angle
5
#5
#4
#3
#2
#1
(π,0)
(π,π)
0.75
0.70
0.65
0.60
0.55
0.50
0.45
0.40
0.35
0.30
0.25
0.20
0.15
0.10
0.05
fraction of the Brillouin zone

High Pressure Transfer Lens - Schematic
Experimental Cell
with temperaturecontrolled
sample,
gas flow control
and variable
distance to nozzle
Four Pressure Zones
(differential pumping)
X-rays enter through a
silicon nitride window
Four Electrostatic Lenses
Hemispherical
Analyzer Lens
D.F. Ogletree, H. Bluhm, Ch. Fadley, Z. Hussain, M. Salmeron, Materials Sciences Division and Advanced Light Source, LBNL.

Photoelectrons
from sample
surface AND
near-surface gas
Ambient pressure soft x-ray
spectroscopy: Concept
controlled
gas atmosphere
e -
hν
synchrotron beam enters
through window (Al or SiN,
~100 nm)
differentially pumped
electron transport

ALS BEAM LINE 9.0.1: Lensless Imaging
Diffraction station built by SUNY/BNL group
Diffraction pattern of
freeze-dried yeast
taken by SUNY gp
Monochromator zone plate
Cryo holder
CCD detector chamber
Sample manipulator
Optimized and dedicated setup could provide 100-1000 times
better efficiency

Scanning Transmission X-ray Microscope
(STXM) 11.0.2
Side view Top view
Interferometer
Detector Zone plate
optics
Sample mechanical stages
and vacuum
window
Sample holder
Piezo scanning stage

Imaging of tantalum oxide aerogel
1 µm
3D isosurface Cross-section
(bar =
200nm)
• 2-micron-wide particle of tantalum oxide aerogel
500 nm cube
res’n 20-30 nm
• Density about 0.1 gm/cm 3 which is about 1.2% of bulk
density
• Applications for NIF target, hydrogen storage
Chapman/Howells/Spence et al - ALS
50 nm

Nanoscience Characterization Facility @ ALS
(bl 8.0)
“User-friendly for nanostructure characterization
endstation” proposal funded by DOE
(U. Wisconsin-Madison, F. Himpsel et al)
(1) Micro-focus (~10 µm) beam spot
(2) Efficient fluorecence yield detectors for XAS
(3) Emission Spectrograph (VLS)
(4) Photoemission (Scienta 100)
System is being commissioned