Effect of Saturation and Velocity Selective Population in 6S1/2→6P3/2 Laser Excitation in Cs Vapor Mixed with Ar
LIU Jing1,2,ZHOU Heng-wei2,3,ZHANG Guo-liang2,3,DAI Kang2,SHEN Yi-fan2*
1. School of Science, Xi’an Jiaotong University, Xi’an 710049, China 2. School of Physics, Xinjiang University, Urumqi 830046, China 3. College of Physics and Electronical Information, Yi Li Normal University, Yining 835000, China
Abstract：The excited state population distribution created by 6S1/2→6P3/2 laser excitation in room temperature cesium vapor mixed with Ar was quantitatively analyzed applying absorption and saturation spectroscopy. A simple method for the determination of the excited state population in a single excitation step based on the measurements of the saturated and unsaturated absorption coefficients was tested. When the line profile is nearly pure Doppler and the laser linewidth is much smaller than the inhomogeneous linewidth but comparable with homogeneous linewidth, the fraction N(vz) of the atoms in the ground state that are able to absorb under inhomogeneous broadening conditions can be determined. The transmission of the medium in the center of the Doppler envelope of the strong h. f. component of the CsD2 line due to hyperfine pumping alone amounts to ≈5%. The assumption that has been made is that the lower-state hyperfine levels are populated in a statistical ratio. The absorption coefficients were measured for a series of P852 powers between 20 μW and 2.5 mW. The velocity selective population density in the 6P3/2 state was obtained. The population in the 6P3/2 level obtained from the saturation measurements was also determined by the absorption measurement of narrow spectral line from a Cs hollow cathode lamp. The agreement between the results obtained in these two ways is very good. It was shown that 5% of the ground state population could be transferred to the first excited state by pumping the Doppler broadened line with a single-mode narrow-band laser. The argon caused line broadening and therefore increased the effective pumping rate in the first excitation step. The dependence of the 852 nm line fluorescence intensity was plotted against the population in the 6P3/2 level determined from the saturation absorption. This can serve as confirmation of the reliability of the method used for the determination of the excited state population.
Key words：Laser spectroscopy;Saturated absorption;Velocity selective population;Cs vapor mixed with Ar
刘静1,2,周恒伟2,3,张国良2,3,戴康2,沈异凡2*. Cs-Ar混合蒸气中6S1/2→6P3/2激光激发的速度选择粒子数密度和饱和效应[J]. 光谱学与光谱分析, 2008, 28(09): 1958-1961.
LIU Jing1,2,ZHOU Heng-wei2,3,ZHANG Guo-liang2,3,DAI Kang2,SHEN Yi-fan2*. Effect of Saturation and Velocity Selective Population in 6S1/2→6P3/2 Laser Excitation in Cs Vapor Mixed with Ar. SPECTROSCOPY AND SPECTRAL ANALYSIS, 2008, 28(09): 1958-1961.
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