Excited state mediated collision induced Raman pumping

Pulsed dye laser induced fluorescence is used to study the interactions between ground state, X 1~+g, sodium dimer and excited state 3P2P3/2 sodium atoms generated at high concentration in supersonic expansion in an extended pa,1t/h2length configuration. A recently discovered resonance Raman pumping process is surveyed to demonstrate the synergy between the collisional iteration of excited state sodium atoms and the Ramanlike scattering of D line photons from ground state sodium dimer. A simple dipoledipole interaction model is found to predict the unusually large broadening linewidth, n 4cm-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, symmetrically, the Na D line do not correlate directly with photon flux but are intimately linked to the presence of an excited state sodium atom (3P) constituency. This suggests the possibility of a long range Na2-Na* interaction as a flyby collision mediates the Raman scattering process. Absorption data for the Na 3PL3S transition are used to estimate the concentration of sodium atoms in the expansion employing several line-broadening models. The characterization of the Na* (3P) excitation and dispersed laser induced fluorescence (DLIF) spectra allow the assessment of collision broadening and self-absorption. The effect of the Raman process on (1) Na (3P1/2,3/2) interatomic collisional energy transfer and (2) the enhancement of the D line component decay rates, furnishing a route for energy disposal, is evaluated.