A3Π and B3Σ– excited states of the SO radical. Part 3.—The 0–0 band spectrum of the A3Π1–X3Σ– transition

Abstract

A frequency-doubled frequency-scanning dye laser has been used to excite ro-vibrationally resolved levels of SO(A³Π₁, ν= 0) at ca. 259 nm. The rotationally resolved laser excitation spectrum of the 0–0 band of the SO(A³Π₁–X³Σ^–) transition is reported here. Rotational assignment of the spectrum is given along with vacuum wavenumbers of the observed lines. The vacuum wavenumber of the band origin was measured to be 38 086.68 ± 0.20 cm^–1. A strong vibrational perturbation is observed to affect the ν′= 0 level, causing a downward shift in the 0–0 band origin of 6.10 cm^–1, referred to its expected position on the basis of extrapolation from higher levels. The rotational structure of the band appears to be perfectly regular, with rotational constants B^′₀= 0.606 ± 0.002 cm^–1, D^′₀= 0–16 cm^–1. The collision-free lifetime of SO(A³Π₁, ν= 0) was determined to be 39.2 ± 3.6 µs.