Real-time observation of polarization dependence of soft x-ray absorption spectrum during chemical reaction under near-ambient pressure conditions

Abstract

The real-time observation of the polarization dependence of soft x-ray absorption spectra during chemical reactions is realized by combining the fluorescence-yield wavelength-dispersive x-ray absorption spectroscopy technique with a 10 Hz switching between horizontal and vertical polarizations. The soft x-ray absorption spectra for both the horizontal and vertical polarizations are recorded every 100 ms with a time difference of 50 ms, which enables the real-time observation of changes in the anisotropic structure around the surface. The technique is applied to the oxidation reaction of a cobalt thin film under an air pressure of up to 25 Pa, and it is suggested that an anisotropic structure appears during the growth of the cobalt oxide species. By using the developed technique, it is expected that the changes in the anisotropic structures, such as molecular orientations, are observed during chemical reactions under near-ambient pressure conditions, which gives a deeper insight into the understanding of the reaction mechanism.