Eigenstate-resolved ν1spectrum 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.
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