Photoionization-efficiency spectrum and ionization energy of C2H5SCl

Photoionization-efficiency (PIE) spectra in the wavelength range of 108–143 nm are measured for C₂H₅SCl produced from reaction systems Cl/Cl₂/C₂H₅SH and Cl/Cl₂/C₂H₅SSC₂H₅ in a discharge-flow reactor coupled to a photoionization mass spectrometer employing a synchrotron as the source of radiation. According to PIE spectra of C₂H₅SCl thus obtained, the ionization energy (IE) is (8.994±0.007) eV. Based on GAUSSIAN-2 calculations, the observed ionization of C₂H₅SCl near the threshold region is likely to form doublet C₂H₅SCl⁺ from singlet C₂H₅SCl; the calculated IE 8.978 eV agrees well with the experimental value. A vibrational frequency of doublet C₂H₅SCl⁺, was found to be (557±60) cm^-1, which agrees satisfactorily with a theoretical value of 560.9 cm^-1.