Double-infrared-resonance investigation of the 2ν3–ν3 transition in SF6 molecules supercooled in a supersonic stream

The spectrum of the 2ν₃–ν₃ transition in sulfur hexafluoride was investigated in a supersonic stream by the double infrared resonance method using tunable diode lasers. The Q-and R-branch spectra of the transition to the sublevel A₁ of the 2ν₃ vibrational multiplet were studied in the range 941–941.6 cm^–1. The results were used to determine the octahedral splitting constant g₂ and the parameter B₂ – B₀, which were 5.2×10^–5 and – 1.8 × 10^–3 cm^–1, respectively. Spectroscopic investigations were also made at 943.5 and 948.3 cm^–1, corresponding to the transitions to the sublevels E and F₂ of the 2ν₃ state. It was found that absorption in the 2ν₃–ν₃ transition band caused photodissociation of (SF₆)n clusters.