Infrared double resonance of SF6 with a tunable diode laser

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Abstract
Double resonance spectroscopy has been carried out on the ν3 band of SF6 using a CO2 laser pump and a tunable diode laser probe. Power broadening of the pumped transition is observed, and a value for the transition moment μ12?0.3×10−18 esu cm is obtained. Off‐resonant pumping of all symmetry components in the J manifold coupled to the pump laser is observed; this is attributed to field‐induced mixing of nearly degenerate fine‐structure levels in the vibrational ground state of the molecule. From the decay of the double resonance signals, we measure relaxation times Pτ= (24±3) nsec Torr for 2‐level signals and Pτ = (43±11) nsec Torr for 3‐level signals, corresponding to an effective cross section of 170 Å2. Excited‐state transitions corresponding to 2ν3←ν3 with J=32 are observed. The implications for multiple infrared photon excitation models are considered.