Stimulated Raman investigation of CO2-laser-excited SF6

Stimulated Raman spectroscopy is used to probe the photoexcitation dynamics of CO₂-laser-excited SF₆ in a molecular free-expansion jet. Time-dependent depletion of rotational levels in the ground state is observed by monitoring the ν₁ Raman spectrum at various delay times after the CO₂-laser excitation pulse. Optical Stark shifts are also seen, at short delay times, arising from resonances of the IR laser pulse with ν₃ transitions from both ground and ν₁ = 1 states. Molecules excited to the ν₃ = 1 level are detected by scanning the ν₁ + ν₃ ? ν₃ hot band. A direct determination of the anharmonicity X₁₃ = ?2.910 ± 0.002 cm^?1 is thus obtained.