Conformational changes accompanying electronic excitation of trifluoronitrosomethane

Abstract

The 690 nm absorption spectrum of CF3NO has been studied in the gas phase at various temperatures and in the condensed phase at 77 K, and assigned to an (nπ*) transition. Analysis of the vibrational structure shows that, while only the eclipsed conformer is stable in the ground state, there are two stable isomers of comparable energy in the excited electronic state. One has an eclipsed conformation, but with the CF3 group tilted away from the oxygen atom. The other has a staggered conformation. In both of the excited state isomers the barrier to internal rotation is higher than in the ground state.