Photon W value for krypton in the M-shell transition region.

Abstract

Absolute W values for krypton have been measured for incident X rays with energies in the range of 85 to 1000 eV, using monochromatic synchrotron radiation and a multiple-electrode ion chamber technique that yields the absolute intensity of the X-ray beam and the photoabsorption cross section. To improve the purity of the incident X rays, the electron storage ring was operated at an energy lower than the normal mode, and thin filters were used. The W values are derived from the measured photon intensity and photoabsorption cross section, using the mean charges of the residual ions obtained in previous work. A considerable oscillation of the W values with the photon energy was found in the region near the krypton 3d electron ionization edge. The results are discussed and compared with data in the literature for low-energy electrons and with the calculations from a model that includes multiple photoionization effects related to inner-shell ionization.