Ultraviolet Absorption Spectrum of SiF2

The electronic absorption spectrum of SiF2 has been recorded in the region 2325 to 2130 Å. The principal feature of the spectrum is the presence of a long progression in the bending frequency of the upper electronic state suggesting that the bond angle F–Si–F undergoes a considerable change during transition. A number of weak bands, identified as arising from the vibrationally excited levels of the lower electronic state, are also observed. There is no definite evidence for excitation of stretching vibrations. The bending frequencies for the lower and upper electronic states are estimated as about 345 and 252 cm−1, respectively. The vibrationless transition (ν1′=0, ν2′=0, ν3′=0←ν1″=0, ν2″=0, ν3″=0) is shown to lie at about 2266.4 Å (44 109 cm−1) and is probably a 1B1←1A1 transition.