Optical Pumping and Atomic Line Shape

Evgenii B. Aleksandrov, S. L. Izotova, A. B. Mamyrin +1 more

S. É. Frish

Get PDF Email Share Share with Facebook Tweet This Post on reddit Share with LinkedIn Add to CiteULike Add to Mendeley Add to BibSonomy Get Citation Copy Citation Text S. E. Frish, "International Conference on Optical Pumping and Atomic Line Shape (OPALS), Warsaw, 25–28 June 1968," Appl. Opt. 8, 904-904 (1969) Export Citation BibTex Endnote (RIS) HTML Plain Text Citation alert Save article

R. A. Zhitnikov

James C. Camparo, R. P. Frueholz, Charles M. Klimcak

Recent experiments have shown that optical pumping can produce line shapes with subnatural structure, and that this structure could prove to be useful for extracting oscillator strengths. A key question, however, regarding the optical-pumping technique's potential usefulness is how well it allows the determination of resonance line center. In the present paper we address this question theoretically by considering laser optical pumping and probing of an atomic beam. From the analysis (i) we find that depending on laser polarization the optical-pumping subnatural feature is either a dip or a signal enhancement, (ii) we derive the rigorously correct formula relating the dip width to the transition oscillator strength for an alkali-like atom exhibiting a homogeneous line shape, and (iii) we show that, compared to shot-noise-limited laser-induced fluorescence, the optical-pumping technique of signal enhancement is capable of a 15% improvement in the ability to find resonance line center.

John E. Bjorkholm, P. F. Liao, Alexander J. Wokaun

We have observed that spectral lines obtained in sodium vapor can be strongly distroted when using two-photon spectroscopy with a resonant intermediate state. In some cases, the spectral lines appear to be split into two components. We demonstrate that these effects are due to velocity-selective optical pumping of the atomic ground state; the line shapes reflect the velocity distribution of atoms in the excited intermediate state. We have analyzed the effects using the time-dependent solutions of the rate equations which describe the time evolution of optical pumping for the various atomic velocity groups, and we obtain good agreement with experiment. Optical-pumping problems are often analyzed with the use of steady-state rate equations which incorporate phenomenological relaxation; such approaches are not capable of describing our observations. Velocity-changing collisions are shown to suppress the effects and they explain why these effects were not previously observed; the previous experiments were carried out with slight amounts of a buffer gas in the vapor cell. The effects reported here must be accounted for when carrying out laser-induced line-narrowing experiments in atoms or molecules that can be optically pumped; they can also be used as a new and more sensitive probe of optical pumping in vapors.