Spectroscopic examination of the luminescence from SiH4and SiH4‐SiF4mixtures that are irradiated with an unfocussed, pulsed CO2infrared laser at a fluence of 0.75 J/cm2shows the emission to be due to the transitions SiH2(1B1, &ngr;′=2, 3) →SiH2(1A1, &ngr;″=1) and thus clearly demonstrates the presence of SiH2in the decomposing gas. The form of the time dependence of the emission is determined by the collisional energy pooling processes that produce highly excited SiH4molecules and does not permit an assessment of the lifetime of the1B1state of SiH2.