Selenoketone spectroscopy: vibronic analysis of the and n → π electronic transitions in F2CSe

Abstract

The spectrum of F2CSe has been surveyed over the 700–200 nm wavelength region and three distinct absorptions identified. These are the spin-allowed, [Formula: see text] and spin-forbidden [Formula: see text] overlapping n → π* transitions, λmax = 434 nm, and the orbitally-allowed [Formula: see text] transition, λmax = 236 nm. Vibrational assignments for the band systems have been made and the out-of-plane energy levels analyzed in terms of a quadratric-Lorentzian double minimum potential. The barriers to inversion for the Ã1A2/ã3A2 states were found to be 2483/2923 cm−1 and the out-of-plane angles 30.1/31.4 deg. The singlet–triplet separation was E(Ã1A2) − E(ã3A2) = 671 cm−1 The [Formula: see text], system displays continuous structure and was not subject to a vibrational analysis.