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Development of light-modulated XAFS spectroscopy
Kaoru Okamoto1, Kenji Kohdate, Kensuke Nagai
1Department of Chemistry, School of Science, The University of Tokyo, Hongo, Bunkyo-ku, Japan.
Journal of Synchrotron Radiation
|April 26, 2003
Summary
This study introduces a light-modulation technique for X-ray absorption fine structure (XAFS) spectroscopy. This method effectively studies light-excited states in materials, even with low excited-state populations.
Area of Science:
- Materials Science
- Spectroscopy
- Physical Chemistry
Background:
- Studying light-excited states requires advanced spectroscopic techniques.
- Traditional methods may lack sensitivity for low-concentration excited states.
Purpose of the Study:
- To develop and validate a light-modulation XAFS method for electronic and structural analysis of light-excited states.
- To assess the applicability of this method to systems with low excited-state ratios.
Main Methods:
- Visible light modulation using an optical chopper for electronic excitation.
- Detection of X-ray absorbance changes via a lock-in amplifier.
- Measurement of Fe and Co K-edge XANES and EXAFS spectra for spin transition compounds.
Main Results:
- The light-modulated XAFS method successfully extracted signals from light-excited states.
- The technique is effective for systems with excited-state ratios below several percent.
- Quantitative analysis, including signal amplitude and phase shift, was demonstrated.
Conclusions:
- Light-modulated XAFS spectroscopy is a viable tool for investigating transient electronic and structural properties.
- The method offers high sensitivity for studying photoexcited phenomena in various materials.