Soft x-ray near edge spectroscopy of cuprous oxide and silicon-germanium alloys

High resolution soft x-ray absorption near edge structure (XANES) spectra have been obtained for CU20 and for SiGe1-x semiconductor alloys, xas a function of composition x, using the methods of partial electron yield and thin film absorption. The shapes of the near edge features provide a unique fingerprint of the local crystal structure (symmetries, coordinations, bond lengths, etc.) in the bulk. A strong asymmetric peak at threshold in Cu20 is probably best described as a Frenkel core exciton corresponding to an allowed Cu 2p + alg molecular orbital transition of the rare linear (0-Cu-0)3-molecular unit characteristic of Cu20. A dramatic change in the observed soft x-ray absorption near edge structure (XANES) for x = 0.15 in SixGe1-x is consistent with the x-dependence predicted for this alloy system by Newman and Dow. The design, operating characteristics, and advantages of the University of Illinois beam line at the 1 GeV electron storage ring Aladdin, including the new extended range grasshopper (ERG) grazing incidence grating monochromator for use in the VUV and soft x-ray spectral ranges, are presented.U of I OnlyThesi