Nonlinear resonance effects in atomic gases—spontaneous and stimulated electronic Raman scattering of Na atoms excited resonantly at D lines by a tunable dye laser

A report is given of the first quantitative study of the spontaneous and stimulated electronic Raman scattering by a resonance doublet of the sodium atom excited resonantly at the D₁ and D₂ lines by a tunable dye laser. Theoretical and experimental analyses of the differential scattering cross section and polarization properties at the Stokes and anti-Stokes frequencies show that the observed scattering is due to a nearly resonant process involving the ground state 3S_1/2 as the dominant intermediate state. The stimulated Stokes and anti-Stokes scattering lines, which are shifted from the D₁ and D₂ lines by an amount corresponding to the frequency separation between lowest-lying excited doublets 3P_1/2 and 3P_3/2, are observed by exciting a sodium vapor cell with a passively mode-locked dye laser.