In a review by Schaack I came across the notion that a possible signature of electronic Raman losses (as opposed to losses due to phonons) is the appearance of a non-symmetric Raman tensor. As far as I understood this would mean (in backscattering geometry, i.e. light propagation essentially along z ) that exciting with linear polarization along x and detecting y-polarized scattered light gives a different result compared to the case with swapped excitation and detector polarizations. (According to that article the reason would be that there are symmetric and antisymmetric parts to the Raman tensor).
I have now tried to derive such a result for the case of (electronic) Raman spectroscopy on single localized 4f electrons (Ce 4f1 config) [Raman losses would then correspond to crystal field excitations].While I do get symmetric and antisymmetric terms, they never combine on the same matrix elements, leaving intensities (matrix elements squared) unmodified.
It seems that I am doing something wrong... Do you know a good reference for looking this up or straight away the condition(s) required to get a non-symmetric Raman tensor?
The reference book for that (difficult to find nowadays) is
Infrared and Raman Spectra of Crystals
by G. turrell,
Academic Press, London, 1972. 384 pages.
The antisymmetric electronic Raman scattering has been only observed for compounds of rare-earth ions (you made mention to them) and the antisymmetric Raman scattering by phonons in non-magnetic crystals is even less important to be experimentally observed. Actually I do not know any compound which presents such property.
One reference which treats this issue and applies explicitly this concept to optical phonons for the point groups Oh and D3 is:
E.M. Anastassakis, Disordered Solids, Optical Properties in Volume 4 on Dynamical Properties of Solids, North Holland, 1980
Thanks to all for the references, which we are now checking.
@Behnam: This book by Powell seems to be nice. However, electronic Raman scattering is not treated explicitely. Nevertheless, there is of course some similarity with the two photon excitation process. Concerning JT-Effect: for our Ce 4f1 configuration, due to crystal field splitting, there is only Kramers degeneracy left and JT is not an issue I believe.
This is a good question.
A detailed answer to this question is given in
C.S. Snow, Probing the dynamics of pressure and magnetic field-tuned transitions in strongly correlated electron systems: Raman scattering studies, Ph.D. thesis, University of Illinois at Urbana-Champaign, 2003:
http://research.physics.illinois.edu/Publications/theses/copies/Snow.pdf
See Section 2.4.1 on General Excitation Symmetries, starting on page 28. See page 111 on all of the Raman scattering measurements performed in a true backscattering configuration.
For solid state Raman spectroscopy, a variety of local environments lead to inhomogeneous broadening, and as a consequence to asymmetric line shape. This effect is often observed for nanoscale materials, and can have multiple origins, such as surface states, phonon confinement by grain boundaries anharmonicity, local heating by the laser, stoichiometry variations and lattice defects .....
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