Coherent Stokes and anti-Stokes Raman spectra of the ν1 ( A1) and ν2 ( E) bands of SF 6 and UF 6

Abstract

Coherent Stokes and anti-Stokes Raman scattering are used to study the ν 1 and ν 2 spectral band profiles of UF 6 and SF 6. Most of the observed SF 6 “hot” bands are assigned, leading to evaluations of the anharmonicity constants X ij : X 12 = −(2.80 ± 0.30) cm −1, X 14 = −(1.00 ± 0.15) cm −1, X 15 = −(1.00 ± 0.15) cm −1. For UF 6, a tentative assignment of the “hot” bands is made: X 12 = −(1.80 ± 0.30) cm −1, X 13 = −(1.60 ± 0.30) cm −1, X 14 = −(0.20 ± 0.10) cm −1, X 15 = −(0.25 ± 0.10) cm −1, and X 16 = −(0.10 ± 0.05) cm −1. Parameters such as the vibration-rotation coupling constants are determined. For SF 6: α = (7 ± 2) × 10 −5 cm −1 for the ν 2 band and α = −(1.02 ± 0.01) 10 −4 cm −1 for the ν 1 band. The calculated spectral profiles of the coherent Stokes or anti-Stokes spectra, which are in good agreement with experimental results, give values for the resonant and nonresonant parts of the susceptibility in both molecules. They also show, in some cases, the influence of neighboring combination bands.