Relativistic Simulations of Mössbauer Spectroscopy
T. Saue
Laboratoire de Chimie et Physique Quantiques, CNRS et Université Paul Sabatier, Toulouse, France.
Mardi 20 Janvier 2015, 11h00
bibliothèque LCT, tour 12 - 13, 4e étage
An important spectroscopic technique, particular in bioinorganic chemistry, is
Mössbauer spectroscopy which relies on the Mössbauer effect, that is, the recoilless emission or absorption of gamma radiation from a nucleus in a (solid) sample. The Mössbauer isomer shift probes the electron density in the close vicinity of the nucleus, whereas the quadrupole splitting is sensitive to deviations from spherical symmetry.
These two Mössbauer parameters therefore provide complementary information from which chemical descriptors such as the spin and the oxidation state of the Mössbauer-active atom can be extracted.
In the present contribution we focus on the Mössbauer isomer shift. After a comprehensive introduction to basic theory, we present a calibration study of the 199Hg isomer shift, comparing the performance of various DFT functionals with CCSD(T) benchmark results. The most widely studied Mössbauer-active isotope is 57Fe. We demonstrate how our simulations combined with experiment allows to distinguish between possible intermediates of iron hydrogenase.