Excited state mediated collision induced Raman pumping

Pulsed dye laser induced fluorescence is used to study the interactions bet ween ground state, X(1)Sigma(g)(+), sodium dimer and excited state 3P P-2(3 /2,1/2) sodium atoms generated at high concentration in supersonic expansio n in an extended path length configuration. A recently discovered resonance Raman pumping process is surveyed to demonstrate the synergy between the c ollisional iteration of excited state sodium atoms and the Raman-like scatt ering of D line photons from ground state sodium dimer. A simple dipole-dip ole interaction model is found to predict the unusually large broadening li newidth, Gamma similar to 4 cm(-1), determined by computer simulation to be associated with the Raman scattering process. Pulsed laser probes indicate that the Raman Stokes and anti-Stokes features which encompass, symmetrica lly, the Na D line do not correlate directly with photon flux but are intim ately linked to the presence of an excited state sodium atom (3P) constitue ncy. This suggests the possibility of a long range Na-2-Na* interaction as a fly-by collision mediates the Raman scattering process. Absorption data f or the Na 3P --> 3S transition are used to estimate the concentration of so dium atoms in the expansion employing several line-broadening models. The c haracterization of the Na* (3P) excitation and dispersed laser induced fluo rescence (DLIF) spectra allow the assessment of collision broadening and se lf-absorption. The effect of the Raman process on (1) Na (3P(1/2,3/2)) inte ratomic collisional energy transfer and (2) the enhancement of the D line c omponent decay rates, furnishing a route for energy disposal, is evaluated.