Investigation of Optical Pumping and Spin Life-time in Cesium Vapor Cells

Abstract

This thesis investigates the impact of temperature and amount of light on dark state life-times after optical pumping. For this the hyperfine structure of the Cs D1 line was investigated. To do this, a Cesium vapour cell containing 5 torr nitrogen as buffer gas was spectroscoped. For comparison, a cell without buffer gas was also measured. The temperature was controlled between (23 ± 5)°C and 87 ± 5°C with a heating element and the beam diameter between (0; 40 ± 0; 08)mm and (2; 20 ± 0; 08)mm with an aperture. The maximum life-times for the buffer gas cell were found between ((2; 15 ± 0; 06) ms for 23 ± 5)°C and (20 ± 0; 6)µs at (87; 2 ± 5)°C. For comparison, the measurements of a cell without buffer gas yielded a life-time of (15:6 ± 0; 5)µs. The calculated diffusion constants do not contain the theoretical values in the error limits, which indicates that diffusion is not the dominating limiting factor for the life-times. Furthermore, the optical depths of the transitions are calculated. The maximum life-time derived from negative optical depth was found to be (15:6 ± 0; 5)ms at the F=4 ! F’=3 at 23 ± 5)°C. Additionally, the optical depths were compared with optical depths without pumping. They only showed similarities at larger beam diameters.