REMPI/MS detection of SiF₂ radicals by (3+1) and (1+3) photoionization

SiF₂ has been detected by resonance-enhanced multiphoton ionization mass spectrometry. Two new absorptions have been observed at 481.30 and 379.94 nm and assigned as the (3+1) photoionization via the B̃ ¹B₂ state and the (1+3) absorption via the ã ³B₁ state. A third absorption is observed between 390 and 430 nm which cannot be assigned to any known electronic states of SiF₂. Most likely, this is a (3+1) photoionization via a Rydberg state. SiF₂ radicals were produced by the reaction of SiF₃H with F atoms and by the reaction of F₂ with heated silicon crystals under single gas-surface collision conditions.