Multiphoton gas phase dissociation of methyl and ethyl formates

Abstract

The IR-multiphoton-initiated decomposition of methyl and ethyl formates is reported. Experiments were carried out by 9.6 pm irradiation under mildly focused conditions, with fluences of about 10 J cm-*. CO, CH4, CO*, C2H, and CHsOH were detected for HCOOCHs while CO, CH,, CzH4, C2H, and traces of CO2 were observed for HCOOC2H,. The product yields were measured by quantitative gas chromatographic analyses. In HCOOC2Hs, the dominant process is the reaction producing ethylene and CO (already observed in pyrolysis and UV photolysis). In HCOOCH3 two presumably unimolecular reactions seem to occur, one producing CO and CHsOH and the other producing CH4 and CO*, in contrast with the assumed mechanisms for pyrolysis and photolysis. The product yields can be interpreted in terms of secondary thermal or radical reactions. The effects of inert gases were studied. Luminescence in the focal region originating from OH -, CH-, C2 and H,0(113) excited species was observed and its temporal behavior studied.