Carbon K-shell x-ray and Auger-electron cross sections and fluorescence yields for selected molecular gases by 0.6 to 2.0 MeV proton impact

Absolute K-shell x-ray cross sections and Auger-electron cross sections are measured for carbon for 0.6 to 2.0 MeV protons incident on CH4, n-C4H10 (n-Butane), i-C4H10 (Isobutane), C6H6 (Benzene), C2H2 (Acetylene), CO and CO2. Carbon K-shell fluorescence yields are calculated from the measurements of x-ray and Auger-electron cross sections. X-ray cross sections are measured using a variable geometry end window proportional counter. An alternate method is described for the measurement of the transmission of proportional counter window. Auger electrons are detected by using a constant transmission energy π/4 parallel plate electrostatic analyzer. Absolute carbon K-shell x-ray cross sections for CH4 are compared to the known results of Khan et al. (1965). Auger-electron cross sections for proton impact on CH4 are compared to the known experimental values of Roedbro et al. (1979), and to the theoretical predictions of the first Born and ESPSSR. The data are in good agreement with both the first Born and ESPSSR, and within the experimental uncertainties with the measurements of Roedbro et al. The x-ray cross sections, Auger-electron cross sections and fluorescence yields are plotted as a function of the Pauling charge, and show significant variations