Collisional and radiative processes in sodium vapor

Sodium vapor, in the density range 1013 - 5 x 1014 cm-3, was excited by a cw dye laser, tuned 20 to 140 GHz from either the D1 or D2 resonance line. The three peak scattered spectrum, consisting of the Rayleigh component at the laser frequency, and the two fluorescence components (direct and sensitized) at the atomic resonance-line frequencies. Corrections to the Rayleigh signals for anisotropy and polarization effects, and to the fluorescence signals for radiation trapping were made in order to obtain the ratio of the intensity of the fluorescence components to that of the Rayleigh component. Combined with a measurement of the line-wing absorption coefficient, the ratio of fluorescence to Rayleigh intensities then yields the sodium D line self-broadening rate coefficients (K/sub Br/(D2) = 4.67E-7 cm3/s and K/sub Br/(D1) = 3.07E-7 cm3/s +- 15%). Asymmetry in the self-broadened line wings due to find structure recoupling was observed. Asymmetry in the Rayleigh scattering, as a function of detuning, was also observed, due to interference between the two fine structure levels. In addition, the measured intensity ratio of the D-lines yields the fine structure collisional mixing cross section (sigma /sub 3P/sub 3/2/→3P/sub 1/2//=172 A2 +- 18%). In a second set of experiments pulsed nitrogen laser pumped dye laser excitation was used, and time-resolved fluorescence signals were recorded. From these data effective 3P/sub J/- state radiative decay rates were obtained in the presence of radiation trapping