Depolarization of NaD2 Fluorescence under Pulsed Laser Excitation

Abstract
The intensity and polarization state of the NaD2-fluorescence (3 2P3/2→3 2S1/2 , λ 5890 Å) from a cell containing pure Na vapor, selectively excited by a flash lamp pumped dye laser was investigated. Measurements were performed both for excitation with π-and σ-light of spectral density ranging between 10-23 and 10-17 Ws2 cm-3 and with Na number densities between 2.8 X109 and 4.0 X 1010 cm-3. The results are interpreted in terms of population of the 2P3/2 state and of hyperfine and Zeeman pumping of the 2S1/2 substates. The values for the degree of linear polarization measured at the smallest excitation densities and Na pressures agree well with theoretical values.