Unimolecular dissociation of energy-selected dimethyl sulfoxide

The fragmentation mechanism of dimethyl sulfoxide ion was studied using threshold photoelectron photoion coincidence (TPEPICO) mass spectrometry. The detailed breakdown graph was obtained in the energy range 9.0–17.5 eV. The appearance potentials of major fragments determined from breakdown curves are lower than those reported from early electron impact studies. The breakdown graph calculated using RRKM-QET is in good agreement with experiment, suggesting that the dissociation of dimethyl sulfoxide ion is statistical.