Multiphoton dissociation/ionisation of dimethyl sulphide (CH3SCH3) at 355 and 532 nm

Multiphoton dissociation/ionization has been studied for CH3SCH3 at 355 and 532 nm using a time-of-flight mass spectrometer. The major ion signals obs erved at 355 nm are C+, CH3+, HCS+, CH2S+, CH3S+ and CH3SCH3+. Power depend ence studies at 355 nm show a (2 + 1) REMPI process for the formation of pa rent ion. Peaks at mle = 46, 47 and 61 show two-photon laser power dependen ce whereas mle = 15 and 45 peaks show four-photon dependence. However, in 5 32 nm photoionisation, no parent ion signal is observed. A peak at mle = 35 corresponding to SH3+ has been observed. SH3+ has been suggested to origin ate from CH3SCH2+ via a cyclic transition state. Photoionisation results of CH3SCH3 have been compared with those of CH3SSCH3 at these two wavelengths .