Inner-shell excitation of acetylene by electron impact

Abstract

The distorted-wave approximation (DWA) is applied to study $K$-shell excitation in ${\mathrm{C}}_{2}{\mathrm{H}}_{2}$ by electron impact. More specifically, calculated differential and integral cross sections for the $X\phantom{\rule{0.2em}{0ex}}^{1}\ensuremath{\Sigma}_{g}^{+}\ensuremath{\rightarrow}^{1,3}\ensuremath{\Pi}_{g}(1s{\ensuremath{\sigma}}_{g}\ensuremath{\rightarrow}1p{\ensuremath{\pi}}_{g})$ and $X\phantom{\rule{0.2em}{0ex}}^{1}\ensuremath{\Sigma}_{g}^{+}\ensuremath{\rightarrow}^{1,3}\ensuremath{\Pi}_{u}(1s{\ensuremath{\sigma}}_{u}\ensuremath{\rightarrow}1p{\ensuremath{\pi}}_{g})$ transitions in this target in the $300--800\phantom{\rule{0.3em}{0ex}}\mathrm{eV}$ incident energy range are reported. The triplet-to-singlet ratios of respective integral cross sections, namely, RI(3:1), calculated by dividing the integral cross sections for transitions leading to the triplet core-excited states by those leading to the corresponding singlet states, are also reported as a function of incident energies. In general, our calculated sums of the generalized oscillator strength for transitions leading to the $^{1}\ensuremath{\Pi}_{g}$ and $^{1}\ensuremath{\Pi}_{u}$ excited states are in good agreement with the available experimental data. On the other hand, the present calculated integral cross sections and the corresponding data for its isoelectronic species CO are significantly different. Possible physical origins for this difference are discussed.