Structural analysis of ultrafast extended x-ray absorption fine structure with subpicometer spatial resolution: Application to spin crossover complexes
- Ecole Polytechnique Federale de Lausanne, Laboratoire de Spectroscopie Ultrarapide, Institut des Sciences et Ingenierie Chimiques, CH-1015 Lausanne-Dorigny (Switzerland)
- Swiss Light Source, Paul Scherrer Institut, CH-5232 Villigen PSI (Switzerland)
We present a novel analysis of time-resolved extended x-ray absorption fine structure (EXAFS) spectra based on the fitting of the experimental transients obtained from optical pump/x-ray probe experiments. We apply it to the analysis of picosecond EXAFS data on aqueous [Fe{sup II}(bpy){sub 3}]{sup 2+}, which undergoes a light induced conversion from its low-spin (LS) ground state to the short-lived ({tau}{approx_equal}650 ps) excited high-spin (HS) state. A series of EXAFS spectra were simulated for a collection of possible HS structures from which the ground state fit spectrum was subtracted to generate transient difference absorption (TA) spectra. These are then compared with the experimental TA spectrum using a least-squares statistical analysis to derive the structural change. This approach reduces the number of required parameters by cancellation in the differences. It also delivers a unique solution for both the fractional population and the extracted excited state structure. We thus obtain a value of the Fe-N bond elongation in the HS state with subpicometer precision (0.203{+-}0.008 A)
- OSTI ID:
- 21255546
- Journal Information:
- Journal of Chemical Physics, Vol. 130, Issue 12; Other Information: DOI: 10.1063/1.3081884; (c) 2009 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA); ISSN 0021-9606
- Country of Publication:
- United States
- Language:
- English
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