Line shapes for attachment of threshold electrons to SF6 and CFCl3: Threshold photoelectron (TPSA) studies of Xe, CO, and C2H2

Abstract

Using the technique of threshold photoelectron spectroscopy by electron attachment (TPSA), the shapes of the threshold electron attachment cross sections for SF₆ and CFCl₃ are determined by direct photoionization measurements of the ²P_1/2 level of Xe⁺. The observed TPSA line shape is deconvoluted using a Lorentizian attachment profile with full‐width at half‐maximum of 30 meV for SF₆ and 25 meV for CFCl₃. In addition, TPSA spectra of the ground electronic states of CO⁺ and C₂H₂⁺ are reported. In CO⁺ the intensity of the threshold spectral features are dominated by autoionization, while for the vibrational features of C₂H₂⁺ direct photoionization is more important. The two processes (autoionization and direct ionization) are characterized by different TPSA spectral line profiles.