Eigenstate-resolved ν1 spectrum of CF3CCH: anharmonic couplings to the bath

Abstract

Using the optothermal technique we have measured the ν₁ fundamental of CF₃CCH in a collimated molecular beam. A linear least-squares fit to the unperturbed K subbands with the band origin fixed at 3329.85 cm^–1 gives the rotational constants as B′= 0.095 853 9(17) cm^–1 and ΔA=–0.000 008 8(22) cm^–1. The perturbed subbands are best fit by an anharmonic coupling to a background state with an interaction matrix element of ca. 0.005 cm^–1. Several other perturbations are noticed in the spectrum.