Spectroscopic detection of silylene in the infrared multiphoton decomposition of silane

Abstract

Spectroscopic examination of the luminescence from SiH4 and SiH4-SiF4 mixtures that are irradiated with an unfocussed, pulsed CO2 infrared laser at a fluence of 0.75 J/cm2 shows the emission to be due to the transitions SiH2(1B1, ν′=2, 3) →SiH2(1A1, ν″=1) and thus clearly demonstrates the presence of SiH2 in the decomposing gas. The form of the time dependence of the emission is determined by the collisional energy pooling processes that produce highly excited SiH4 molecules and does not permit an assessment of the lifetime of the 1B1 state of SiH2.