A development of absorption spectra for wide energy region by inelastic x-ray scattering

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Optical properties such as absorption coefficient and reflectivity are no only one of the most fundamental properties of matters but also are related to other properties like dielectric constants and van der Waals force. In particular, interactions of the material with x-rays and charged particles are also described by optical data, as long as they are known over wide energy range. Because of various experimental difficulties however, measurements of optical constants in the vacuum-uv and soft x-ray region are scarce, and are practically nonexistence about liquids. In this project an attempt is made to establish a new spectroscopic method that makes it possible to obtain spectra of various liquids over wide energy region by the use of inelastic scattering of hard x-rays.A new spectrometer which features versatility has been constructed with the present grant-in-aid, and it was sent to synchrotron radiation facilities (Photon Factory at Tsukuba and National Synchrotron Light Source at Brookhaven, U.S.A.). Measurements were carried out there and we have succeeded in obtaining inelastic x-ray scattering spectra of several liquids including water between 0 and 200 eV, which can be transformed to optical constants in the vacuum uv region. The data on water makes a basis of radiation chemistry, and a review paper has been written to the Journal of Japanese Radiation Chemistry Society.In addition, x-ray structure factor can also be deduced from momentum-transfer dependence of inelastic x-ray scattering spectra, which is closely related with electron correlation. The results have been analyzed in terms of the configuration interaction method as well as newly developed coupled cluster method.