Polarization of Pb Vapor. III. Collisional Quenching and Depolarization of Alignment of Pb Metastable and Excited States

Hyatt M. Gibbs

doi:10.1103/PhysRevA.5.2408

Abstract

Several states of Pb were excited and studied in detail by simple optical techniques with data averaging. Cross sections for depolarization of alignment (in $Å^{2}$ at 850°K, ±20%: He, 28; Ne, 46; Ar, 73; Xe, 105) and upper limits on quenching cross sections were determined for the ${}^{3}P_{1}^{o}$ excited state of ${Pb}^{208}$ by monitoring the reduction in the polarization of the fluorescence as a function of foreign-gas pressure. Optical-pumping Zeeman resonances were detected in optically produced and polarized ${}^{3}P_{1}$ , ${}^{3}P_{2}$ , and ${}^{1}D_{2}$ metastable states and $g_{J}$ ratios determined in ${Pb}^{208}$ : $\frac{g_{J} ({}^{3}P_{1})}{g_{J} ({}^{3}P_{2})} = 1.17698 (15)$ and $\frac{g_{J} ({}^{1}D_{2})}{g_{J} ({}^{3}P_{2})} = 0.96158 (33)$ . The $g_{J} ({}^{1}D_{2})$ due to Lurio and Landman implies $g_{J} ({}^{3}P_{2}) = 1.2753 (4)$ and $g_{J} ({}^{3}P_{1}) = 1.5010 (5)$ . From the dependence upon foreign-gas pressure of the optical-pumping recovery times after rf depolarization, the following cross sections for depolarization of alignment were deduced for the ${}^{3}P_{1}$ and ${}^{3}P_{2}$ states, respectively (in $Å^{2}$ at 813 °K, ±20%): He, 27, 36; Ne, 27, 35; Ar, 51, 59; Kr, 64, 76; Xe, 123, 159; $H_{2}$ , 26, 39; $N_{2}$ , 73, 88. The ${}^{3}P_{1}$ quenching cross sections were found to be less than $10^{- 21}$ ${cm}^{2}$ for the rare gases, ≤1.3× $10^{- 21}$ ${cm}^{2}$ for $N_{2}$ , 24(5)× $10^{- 20}$ ${cm}^{2}$ for $H_{2}$ , and ≤0.3× $10^{- 20}$ ${cm}^{2}$ for $D_{2}$ . The ${}^{3}P_{1}$ radiative lifetime of 53±30 msec was also extracted. Comparisons are made between some of the above experimental quantities and theoretical predictions.

Received 30 August 1971

DOI:https://doi.org/10.1103/PhysRevA.5.2408

Physical Review A

covering atomic, molecular, and optical physics and quantum information