Efficiencies for diffraction of 45-275-eV x rays into orders by interferometrically formed, electrodeposited, gold transmission gratings have been measured on the 4 degrees beam line at the Stanford Synchrotron Radiation Project (SSRP). Anomalous dispersion affects the observed efficiency since the gold is partially transmitting to x rays. Model calculations which include anomalous dispersion are in good agreement with observations. With a suitable choice of material and thickness, a grating can be optimized for a given wavelength range by reducing the zero order transmission and enhancing the higher orders. Even orders are suppressed for a grating with equal slit and wire sizes.
Using synchrotron radiation and a new two-grating grazing-incidence monochromator specially designed to remove higher-order components, the relative intensities of double-photoionization transitions have beeri measured in helium, neon, and argon between 70 and 200 eV by ion spectrometry. Extensive tests of a new ion spectrometer were undertaken to eliminate any charge discrimination for the ions. These new results resolve discrepancies existing between previous experimental data and favor, in general, the earliest results of Carlson for photon energies higher than 100 eV. For helium and neon they are in good qualitative agreement with theoretical calculations that include electron-electron correlations. In particular they agree very well with the many-body perturbation-theory approach of Chang and Poe in the case of neon.
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