Collision effects in velocity-selective optical pumping of sodium

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© 1983 American Physical Society (APS). http://www.aps.org

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Volume Title

School of Science | A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä

Date

1983

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Mcode

Degree programme

Language

en

Pages

722-737

Series

Physical Review A, Volume 28, Issue 2

Abstract

We report on a quantitative experimental investigation of velocity-changing collisions by means of velocity-selective optical pumping (VSOP). We have calculated the VSOP line shape for an atom with hyperfine structure with the use of two phenomenological kernels for the collision effects: the Keilson-Storer kernel, and a two-term kernel consisting of a broad Keilson-Storer part and a narrower Gaussian component. Corrections were included to account for the finite absorption in the sample and the backward reflection of the pumping beam. The experiments were carried out in sodium vapor with neon as the perturber gas. The D1 line of sodium was used for optical pumping, and the orientation of the ground state was detected. Free parameters of the theory were determined by fitting the predicted line shapes to experimental curves. The Keilson-Storer kernel proved unsatisfactory, but the two-term kernel reproduced well the observed line shapes over the entire collision profiles in the neon pressure range 0-57 mtorr. In an independent experiment using rapidly modulated VSOP we also measured directly the cross section of velocity-changing collisions: σ=(1.13±0.10)×10exp−14 cm2. The large weight obtained for the narrow Gaussian from the fits, as well as the collision cross section which is three times as large as the cross section deduced from tabulated gas kinetic radii, may indicate the presence of collisions with relatively small velocity changes in addition to hard-sphere encounters.

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Keywords

velocity-selective optical pumping, VSOP, velocity-changing collisions, sodium, kernels, line shape

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Citation

Aminoff, C. G. & Javanainen, Juha & Kaivola, Matti. 1983. Collision effects in velocity-selective optical pumping of sodium. Physical Review A. Volume 28, Issue 2. P. 722-737. ISSN 1094-1622 (electronic). ISSN 1050-2947 (printed). DOI: 10.1103/physreva.28.722.