Threshold photoelectron spectroscopy of organosulfur radicals

Abstract

We report vibrationally resolved threshold photoelectron spectra of several sulfur-containing reactive intermediates. This includes the organosulfur radicals CH₂S, CH₃S, CH₂SH, CH₃S₂, and S₂H, which are relevant in atmospheric chemistry and in astrochemical settings. Due to the high reactivity, the radicals were prepared in situ via pyrolysis of (CH₃)₂S₂. The organosulfur species were characterized by photoion mass-selected threshold photoelectron spectroscopy, employing the photoelectron-photoion coincidence setup (PEPICO) and synchrotron radiation from the Swiss Light Source. We report improved ionization energies and characterize ionic ground and excited states, both singlet and triplet. The vibrational structure was simulated based on computed geometries and vibrational frequencies, giving insight into the geometry change upon ionization.