Observing photochemical transients by ultrafast x-ray absorption spectroscopy
With the advent of femtosecond (fs) time resolution in spectroscopic experiments, it is possible to study the evolution of nuclear motions in chemical and photochemical reactions. In general, the reaction is clocked by an initial fs laser pulse (which establishes the zero of time) and the dynamics are probed by conventional spectroscopy. Replacing the probe laser with an X-ray pulse to perform X-ray absorption (XAS) holds the promise of directly observing the change of electronic structure (via x-ray near-edge absorption: XANES) and of the atomic motions (via x-ray absorption fine structure: XAFS). So far time-resolved XAS has been limited to the ms-ns time domain. Here we report the detection of transient chemical changes in the picosecond time domain, upon ultrashort laser pulse excitation of [Ru(bpy){sub 3}]{sup 2+} in a water solution. We are able to detect the change of oxidation state of the Ru atom with the zero of time unambiguously established. These results provide us with a means to prospect future time-resolved XAS experiments for the direct observation of the underlying nuclear dynamics in solids, liquids and dense gases by which chemical and biochemical reactions occur.
- Research Organization:
- Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
- Sponsoring Organization:
- USDOE
- DOE Contract Number:
- AC03-76SF00098
- OSTI ID:
- 842237
- Report Number(s):
- LBNL-53216; PRLTAO; R&D Project: 458080; TRN: US200516%%133
- Journal Information:
- Physical Review Letters, Vol. 90, Issue 4; Other Information: Journal Publication Date: 01/31/2003; ISSN 0031-9007
- Country of Publication:
- United States
- Language:
- English
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