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Title: Effects of velocity-changing collisions on two-photon and stepwise-absorption spectroscopic line shapes

Abstract

We report the results of an experimental study of the effects of velocity-changing collisions on two-photon and stepwise-absorption line shapes. Excitation spectra for the 3S/sub 1/2/ ..-->.. 3P/sub 1/2/ ..-->.. 4D/sub 3/2/ transitions of sodium atoms undergoing collisions with foreign gas perturbers are obtained. These spectra are obtained with two cw dye lasers. One laser, the pump laser, is tuned 1.6 GHz below the 3S/sub 1/2/ ..-->.. 3P/sub 1/2/ transition frequency and excites a nonthermal longitudinal velocity distribution of excited 3P/sub 1/2/ atoms in the vapor. Absorption of the second (probe) laser is used to monitor the steady-state excited-state distribution which is a result of collisions with rare gas atoms. The spectra are obtained for various pressures of He, Ne, and Kr gases and are fit to a theoretical model which utilizes either the phenomenological Keilson-Stoerer or the classical hard-sphere collision kernel. The theoretical model includes the effects of collisionally aided excitation of the 3P/sub 1/2/ state as well as effects due to fine-structure state-changing collisions. Although both kernels are found to predict line shapes which are in reasonable agreement with the experimental results, the hard-sphere kernel is found superior as it gives a better description of the effects ofmore » large-angle scattering for heavy perturbers. Neither kernel provides a fully adequate description over the entire line profile. The experimental data is used to extract effective hard-sphere collision cross sections for collisions between sodium 3P/sub 1/2/ atoms and helium, neon, and krypton perturbers.« less

Authors:
; ;
Publication Date:
Research Org.:
Bell Laboratories, Holmdel, New Jersey 07733
OSTI Identifier:
5449076
Resource Type:
Journal Article
Journal Name:
Phys. Rev., A; (United States)
Additional Journal Information:
Journal Volume: 21:6
Country of Publication:
United States
Language:
English
Subject:
74 ATOMIC AND MOLECULAR PHYSICS; ATOM-ATOM COLLISIONS; ENERGY-LEVEL TRANSITIONS; HELIUM; KRYPTON; NEON; SODIUM; ABSORPTION SPECTROSCOPY; DISTRIBUTION; LINE WIDTHS; VELOCITY; ALKALI METALS; ATOM COLLISIONS; COLLISIONS; CRYOGENIC FLUIDS; ELEMENTS; FLUIDS; METALS; NONMETALS; RARE GASES; SPECTROSCOPY; 640304* - Atomic, Molecular & Chemical Physics- Collision Phenomena

Citation Formats

Liao, P F, Bjorkholm, J E, and Berman, P R. Effects of velocity-changing collisions on two-photon and stepwise-absorption spectroscopic line shapes. United States: N. p., 1980. Web. doi:10.1103/PhysRevA.21.1927.
Liao, P F, Bjorkholm, J E, & Berman, P R. Effects of velocity-changing collisions on two-photon and stepwise-absorption spectroscopic line shapes. United States. https://doi.org/10.1103/PhysRevA.21.1927
Liao, P F, Bjorkholm, J E, and Berman, P R. 1980. "Effects of velocity-changing collisions on two-photon and stepwise-absorption spectroscopic line shapes". United States. https://doi.org/10.1103/PhysRevA.21.1927.
@article{osti_5449076,
title = {Effects of velocity-changing collisions on two-photon and stepwise-absorption spectroscopic line shapes},
author = {Liao, P F and Bjorkholm, J E and Berman, P R},
abstractNote = {We report the results of an experimental study of the effects of velocity-changing collisions on two-photon and stepwise-absorption line shapes. Excitation spectra for the 3S/sub 1/2/ ..-->.. 3P/sub 1/2/ ..-->.. 4D/sub 3/2/ transitions of sodium atoms undergoing collisions with foreign gas perturbers are obtained. These spectra are obtained with two cw dye lasers. One laser, the pump laser, is tuned 1.6 GHz below the 3S/sub 1/2/ ..-->.. 3P/sub 1/2/ transition frequency and excites a nonthermal longitudinal velocity distribution of excited 3P/sub 1/2/ atoms in the vapor. Absorption of the second (probe) laser is used to monitor the steady-state excited-state distribution which is a result of collisions with rare gas atoms. The spectra are obtained for various pressures of He, Ne, and Kr gases and are fit to a theoretical model which utilizes either the phenomenological Keilson-Stoerer or the classical hard-sphere collision kernel. The theoretical model includes the effects of collisionally aided excitation of the 3P/sub 1/2/ state as well as effects due to fine-structure state-changing collisions. Although both kernels are found to predict line shapes which are in reasonable agreement with the experimental results, the hard-sphere kernel is found superior as it gives a better description of the effects of large-angle scattering for heavy perturbers. Neither kernel provides a fully adequate description over the entire line profile. The experimental data is used to extract effective hard-sphere collision cross sections for collisions between sodium 3P/sub 1/2/ atoms and helium, neon, and krypton perturbers.},
doi = {10.1103/PhysRevA.21.1927},
url = {https://www.osti.gov/biblio/5449076}, journal = {Phys. Rev., A; (United States)},
number = ,
volume = 21:6,
place = {United States},
year = {Sun Jun 01 00:00:00 EDT 1980},
month = {Sun Jun 01 00:00:00 EDT 1980}
}