The T 1←S 0 Absorption Spectrum of Gaseous 4H-Pyran-4-thione

Abstract

The T 1←S 0 absorption spectrum of 4H-pyran-4-thione (PT) was measured in a static cell at room temperature (550–620 nm) and in a seeded cold supersonic jet (580–600 nm) using the cavity ring-down (CRD) method. In the static cell absolute extinction coefficients were determined between 573 and 610 nm with an accuracy of ∼±5%. In this region 22 harmonic sequences and 18 hot bands were observed. The energetically lowest ground state vibration at 167.5 cm −1 was identified as the promoting mode in the static PT gas. The mode in the triplet state was found at 152.3 cm −1. The CRD absorption spectra of static PT gas and jet-cooled PT are compared with the phosphorescence excitation spectrum of isolated PT. The weak S 1, 0←S 0, 0 absorption was tentatively assigned to a transition at ∼17433 cm −1.