Light-modulated XAFS spectroscopy for photo-induced structural changes

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

Research output: Chapter in Book/Report/Conference proceedingChapter

Abstract

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.

Original languageEnglish
Title of host publicationPhysica Scripta T
Pages1050-1052
Number of pages3
VolumeT115
DOIs
Publication statusPublished - 2005
Externally publishedYes
Event12th X-ray Absorption Fine Structure International Conference, XAFS12 - Malmo, Sweden
Duration: 2003 Jun 232003 Jun 27

Other

Other12th X-ray Absorption Fine Structure International Conference, XAFS12
CountrySweden
CityMalmo
Period03/6/2303/6/27

Fingerprint

spectroscopy
electric choppers
amplifiers
excitation
light modulation
monochromators
electronics
frequency modulation
light sources
x rays
phase shift
ground state
shift

ASJC Scopus subject areas

  • Physics and Astronomy(all)

Cite this

Okamoto, K., Kohdate, K., Nagai, K., Miyawaki, J., Kondoh, H., Yokoyama, T., ... Ohta, T. (2005). Light-modulated XAFS spectroscopy for photo-induced structural changes. In Physica Scripta T (Vol. T115, pp. 1050-1052) https://doi.org/10.1238/Physica.Topical.115a01050

Light-modulated XAFS spectroscopy for photo-induced structural changes. / Okamoto, K.; Kohdate, K.; Nagai, K.; Miyawaki, J.; Kondoh, Hiroshi; Yokoyama, T.; Nojima, A.; Ohta, T.

Physica Scripta T. Vol. T115 2005. p. 1050-1052.

Research output: Chapter in Book/Report/Conference proceedingChapter

Okamoto, K, Kohdate, K, Nagai, K, Miyawaki, J, Kondoh, H, Yokoyama, T, Nojima, A & Ohta, T 2005, Light-modulated XAFS spectroscopy for photo-induced structural changes. in Physica Scripta T. vol. T115, pp. 1050-1052, 12th X-ray Absorption Fine Structure International Conference, XAFS12, Malmo, Sweden, 03/6/23. https://doi.org/10.1238/Physica.Topical.115a01050
Okamoto K, Kohdate K, Nagai K, Miyawaki J, Kondoh H, Yokoyama T et al. Light-modulated XAFS spectroscopy for photo-induced structural changes. In Physica Scripta T. Vol. T115. 2005. p. 1050-1052 https://doi.org/10.1238/Physica.Topical.115a01050
Okamoto, K. ; Kohdate, K. ; Nagai, K. ; Miyawaki, J. ; Kondoh, Hiroshi ; Yokoyama, T. ; Nojima, A. ; Ohta, T. / Light-modulated XAFS spectroscopy for photo-induced structural changes. Physica Scripta T. Vol. T115 2005. pp. 1050-1052
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