Infrared double resonance of SF6 with a tunable diode laser

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.