title: Development of light-modulated XAFS spectroscopy.
abstract: The light-modulation method was applied to XAFS spectroscopy as a useful tool for electronic and structural studies of light-excited states. The visible light for electronic excitation was modulated by an optical chopper and the concomitant change in the X-ray absorbance was extracted by a lock-in amplifier. It is essential to reduce any noise arising from several sources, especially those generated by the X-ray monochromator. Fe and Co K-edge XANES and EXAFS spectra were measured using the present approach for spin transition compounds. The light-modulated XAFS method is found to be applicable to systems with an excited-state ratio of less than several percent. Detailed discussion is also given concerning quantitative measurements, including the signal amplitude and phase shift information.
authors.affiliation: Department of Chemistry, School of Science, The University of Tokyo, Hongo, Bunkyo-ku, Japan.
authors.forename: Kaoru
authors.initials: K
authors.lastname: Okamoto
authors.forename: Kenji
authors.initials: K
authors.lastname: Kohdate
authors.forename: Kensuke
authors.initials: K
authors.lastname: Nagai
authors.forename: Jun
authors.initials: J
authors.lastname: Miyawaki
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Kondoh
authors.forename: Toshihiko
authors.initials: T
authors.lastname: Yokoyama
authors.forename: Akihiro
authors.initials: A
authors.lastname: Nojima
authors.forename: Toshiaki
authors.initials: T
authors.lastname: Ohta