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Methoden und Instrumentierung Poster: Mi., 14:00–16:30 M-P77
SRPAC: basic features and first applications
I. Sergueev 1 , T. Asthalter 2 , U. van Bürck 3 , A.I. Chumakov 1,4 , C. Strohm 1,3 ,
R. Rüffer 1 , G.V. Smirnov 4 , W. Petry 3
1 European Synchrotron Radiation Facility ESRF, F-38043 Grenoble, France –
2 Physikalische Chemie II, Universität Stuttgart, D-70569 Stuttgart, Germany –
3 Physik-Dept. E13, Technische Universität München, D-85748 Garching, Germany
– 4 Russian Research Center “Kurchatov Institute”, 123182 Moscow, Russia
Nuclear resonant scattering (NRS) of synchrotron radiation (SR) has become an established
field in solid state research, involving mainly two methods: nuclear forward
scattering (NFS) and nuclear inelastic scattering (NIS) [1]. Presently a third method
is being developed, nuclear incoherent scattering observed on the time scale. This
method is essentially a synchrotron radiation based analogue of Time Differential Perturbed
Angular Correlations (TDPAC) [2]. By contrast to TDPAC, in Synchrotron
Radiation based Perturbed Angular Correlations (SRPAC) the intermediate nuclear
level is not excited from above, via a cascade of preceding nuclear transitions after
decay of a radioactive parent, but from below from the ground state during spatially
incoherent, single-nucleus resonant scattering of SR [3]. In both methods the interference
of indistinguishable paths via an intermediate nuclear level split by magnetic
dipole and/or electric quadrupole interaction allows one to investigate hyperfine interactions
and spin dynamics. SRPAC can be applied to all nuclei with isomeric states
with energies attainable by SR.
SRPAC can also be considered as an extension of Mössbauer spectroscopy or NFS into
domains where these methods break down due to a vanishing Lamb-Mössbauer factor:
for relatively low-energy transitions (e.g. 57 Fe, 119 Sn) in very soft matter like melts
and liquids, or for relatively high-energy transitions (e.g. 61 Ni, 67 Zn) in solid matter
e.g. at room temperature.
The basic features of SRPAC have been described recently [4]. SRPAC has been
successfully applied so far using the 14.4 keV transition of 57 Fe for the investigation
of rotational dynamics in glass-formers [4,5], in plastic crystals [6,7], and of probes
confined to one-dimensional channels [8]. The feasibility at high energies has been
demonstrated for the 67.4 keV-transition of 61 Ni [9]. The combination of SRPAC in
hard matter and NIS has been used for a site-specific determination of a phonon DOS
[10].
[1] NRSSR, eds. E. Gerdau and H. de Waard, Hyperfine Interact. 123/124 (1999),
125 (2000). [2] see e.g. T. Butz, Z. Naturforsch. 51a (1996) 396. [3] A.Q.R. Baron et
al., Europhys. Lett. 34 (1996) 331. [4] I. Sergueev et al., Phys. Rev. B 73 (2006)
024203. [5] I. Sergueev et al., in preparation. [6] T. Asthalter et al., J. Phys. Chem.
Solids 66 (2005) 2271. [7] T. Asthalter et al., J. Phys. Chem. Solids 67 (2006) in
press. [8] T. Asthalter et al., in preparation. [9] O. Leupold et al., in preparation. [10]
M. Seto et al., Phys. Rev. Lett. 91 (2003) 185505.