Light-modulated XAFS spectroscopy for photo-induced structural changes

K. Okamoto, K. Kohdate, K. Nagai, J. Miyawaki, H. Kondoh, T. Yokoyama, A. Nojima, T. Ohta

研究成果: Conference article査読


The light-modulation method was applied to XAFS spectroscopy as a useful tool for the electronic and structural studies of light-excited states. Visible light for electronic excitation was modulated by an optical chopper and concomitant change in the x-ray absorbance was extracted by a lock-in amplifier. It is essential to reduce noises arising from several sources, especially those generated by the x-ray monochromator. Light-induced changes were measured successfully by the present approach with high S/N ratios for the Fe and Co K-edge XANES and EXAFS spectra of spin transition compounds. It is also possible to construct the pure EXAFS k3χ(k) for the light-induced state from the light-modulated EXAFS difference spectrum. Detailed experiments including the signal amplitude and phase shift information revealed that the two components with different rate constants can be discriminated by changing the modulation frequency. The light-modulated XAFS method is found to be applicable to the systems with the excited-state ratio less than several percents. It has the following advantages; (1) simple experimental setup, which requires only a visible-light source, an optical chopper, a lock-in amplifier, and a conventional XAFS beamline, and (2) free from the ground-state components because the light-induced absorbance difference is directly detected.

ジャーナルPhysica Scripta T
出版ステータスPublished - 2005
イベント12th X-ray Absorption Fine Structure International Conference, XAFS12 - Malmo, Sweden
継続期間: 2003 6月 232003 6月 27

ASJC Scopus subject areas

  • 原子分子物理学および光学
  • 数理物理学
  • 凝縮系物理学
  • 物理学および天文学一般


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