High repetition rate ultrafast time-resolved X-ray absorption spectroscopy

by Dr. Christopher Milne (Paul Scherrer Institut, Switzerland)

Friday, July 1, 2011 from to (Europe/Berlin)
at AER 19 ( 3.11 )
Using X-ray absorption spectroscopy (XAS) to probe laser-excited samples we can obtain excited-state structural and electronic dynamical information not available through other techniques. One of the restrictions of most synchrotron-based implementations of this technique is the three-orders of magnitude mismatch between X-ray and laser repetition rates (MHz vs. kHz). By using a laser capable of generating significant pulse energies at MHz repetition rates we can eliminate this discrepancy, thus greatly reducing measurement times and enhancing achievable signal-to-noise ratios. Several examples that demonstrate the strength of this technique will be presented, including spin-state investigations of a molecular system using transient XAS on pre-edge transitions, probing the metal-to-ligand-charge-transfer ground-state nature of a Re-halide molecular complex, resolving the ligand rebinding dynamics of the protein myoglobin under physiological conditions, and observing the solvent dependence of the photo-generated-solvated-electron recombination rate with Fe(CN)6.