文献类型：期刊文献

英文题名：Radiation trapping effect and measurement of the Cs(6P_3/2) level effective radiation rate in the vapor mixed with He

作者：Shen Xiao-yan[2];Dai Kang[1];Shen Yi-fan[1]

机构：[1]Xinjiang Univ, Dept Phys, Urumqi 830046, Peoples R China;[2]E China Univ Sci & Technol, Dept Chem, Shanghai 200237, Peoples R China

年份：2008

卷号：28

期号：7

起止页码：1464

外文期刊名：SPECTROSCOPY AND SPECTRAL ANALYSIS

收录：;WOS:【SCI-EXPANDED(收录号:WOS:000258113200006)】；

语种：英文

外文关键词：laser spectroscopy; effective radiation rate; radiation trapping; pressure broadening; Cs-He mixture

摘要：The effective radiation rate for Cs(6P(3/2)) resonance level in the presence of helium was determined. A cell filled with Cs metal and He at pressure P-He (0-500 Pa) was established at T=300 K. The cell was heated in the temperature range between 330 and 370 K, which produced Cs number densities approximately in the range between 10(12) and 10(13) cm(-3). Cs atoms were excited to the 6P3/2 state using a single-mode diode laser(pump laser). The transmission of the medium at the center of the Doppler envelope of the strong h. f. component of the CsD2 line clue to hyperfine pumping alone amounts to approximate to 5%. The assumption that has been made is that the lower-state hyperfine levels are populated in a statistical ratio. The excited-atom density and spatial distribution were mapped by monitoring the absorption of a counterpropagating single-mode diode laser beam (probe laser) tuned to the 6P(3/2)-> 8S(1/2) transition which could be translated parallel to the pump beam. In the presence of radiation trapping., the spontaneous radiation rate is multiplied by the transmission factor T-6P3/2 -> 6S1/2, which describes the average probability that photons emitted within the fluorescence detection region can pass through the optically thick vapor without being absorbed. The T-6P3/2 -> 6S1/2 is related to the frequency dependent absorption cross section and the density and spatial distribution of atoms at the level of the transition. Position dependent 6P(3/2) state densities were combined with the collisional broadening rate of 6P(3/2)<- 6S(1/2) line due to the perturbation of both helium and cesium to yield T-6P3/2 -> 6S1/2. The effective radiation rates of the Cs D-2 line as a function of the He pressure P-He were obtained. The helium caused line broadening and therefore increased the effective radiation rate. The fluorescence intensity I-852 of the 6P(3/2)-> 8S(1/2) emission was measured simultaneously. The measured fluorescence ratios determined the ratios of the effective radiation rates at different He density. These ratios are in agreement with theoretical evaluation.