Showing papers on "XANES published in 1966"

Theory of the extended X-ray absorption fine structure

Abstract: A general formula has been developed for the fluctuations in the X-ray absorption coefficients observed on the high-energy side of an absorption edge, on the assumption that the ejected photoelectron undergoes inelastic collisions in the vicinity of the absorbing atom only. For the intermediate energy range 50-250 eV the directional dependence of the scattering event has been taken into account by replacing the atoms at a given distance from the absorbing atom by a continuous distribution on a spherical shell of the same radius. The positions of the absorption maxima and minima have been calculated for copper and compared with experiment. Reasonable agreement has been found between the experimental results and the present calculations.

Soft X-Ray Absorption Spectra of Alkali Halides. I. KCl and NaCl

Abstract: Soft X-ray absorption spectra of typical alkali chlorides, KCl and NaCl, were observed by using as a continuous background the synchrotron radiation from the 750 MeV electron synchrotron in the Institute for Nuclear Study, Tokyo. The L 2,3 -absorption spectrum of Cl - in these chlorides has been obtained. The spectrum shows one or two sharp absorption maxima at the long wavelength limit and a rapid increase in absorption at about 9 eV above the limit. A shoulder-like structure is observed at the foot of the second absorption band. A tentative X-ray energy level diagram suggests that the shoulder corresponds to the onset of interband transition from L 3 to the conduction band. The first absorption maximum is accordingly interpreted as the excitation of a stable X-ray exciton; a metastable X-ray exciton seems to be involved in the second maximum. The spectral behavior of the L 2,3 -absorption near the long wavelength limit has some similarity to the optical absorption spectrum in the vacuum ultraviolet regi...