The well-known theory of absorption and fluorescence is briefly reviewed in a systematic manner for the Na D transitions. The resulting formalism is applied to simulation of Doppler-free saturation fluorescence spectra. With only one adjusting parameter, the nonradiative rate chosen to represent the time a thermal atom takes to move across the laser beams, the simulated Doppler-free spectra match the measured ones well for both D1 and D2 transitions over one decade of excitation intensities. Relative to the weighted center of the six D2 hyperfine transition lines, the frequencies of the dominant Doppler-free features have been determined from a simulated spectrum to within ±0.1 MHz to be -651.4, 187.8, and 1068.0 MHz, respectively, for D2a, crossover, and D2b resonances. These features may be used as accurate frequency references for atmospheric spectroscopy. They are essential for the operation of the newly developed narrow-band Na fluorescence lidar for wind and temperature measurements in the mesopause region.
© 1995 Optical Society of America
C. Y. She and J. R. Yu, "Doppler-free saturation fluorescence spectroscopy of Na atoms for atmospheric application," Appl. Opt. 34, 1063-1075 (1995)