Broadening of the Sodium D Lines by Atomic Hydrogen. An Analysis in Terms of the NaH Molecular Potentials

E. L. Lewis, L. F. McNamara, and H. H. Michels
Phys. Rev. A 3, 1939 – Published 1 June 1971
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Abstract

The interatomic forces between sodium and hydrogen atoms which are responsible for the broadening of the sodium D lines are discussed in terms of calculated interatomic potential curves for the NaH molecule. The importance of including overlap interactions and of considering both upper and lower states of the transitions is emphasized. A calculation of the line broadening using a molecular model for the pair of colliding atoms with the correct adiabatic limits yields damping parameters of 8.3 × 109 rad sec1 with an estimated accuracy of 5-10% under the conditions of the solar photosphere and fits well with the observed wings of the absorption line profiles. The temperature dependence of the broadening is found to be approximately T0.42, and the width/shift ratios are of the order of 30:1 for both resonance lines. Cross sections for transitions induced between the fine-structure states P322 and P122 are estimated, and the value σ1232=(70±10)πa02 at a velocity of 1.28 × 106 cm sec1 is in agreement with previous calculations. Ground-state spin-exchange cross sections are estimated for hydrogen-sodium collisions as 22πa02 in the same velocity range.

  • Received 17 December 1970

DOI:https://doi.org/10.1103/PhysRevA.3.1939

©1971 American Physical Society

Authors & Affiliations

E. L. Lewis*,§, L. F. McNamara†,§, and H. H. Michels‡,§

  • Joint Institute for Laboratory Astrophysics, University of Colorado, Boulder, Colorado 80302

  • *Visiting Fellow, 1969-1970; on leave from Clarendon Laboratory, University of Oxford, Oxford, England. Present address: Department of Atomic Physics, The University, Newscastle upon Tyne, NE1 7RU, England.
  • Present address: Ionospheric Prediction Service Division, Commonwealth Center, Sydney N. S. W., 2000, Australia.
  • Visiting Fellow, 1969-1970; on leave from United Aircraft Research Laboratories, East Hartford, Conn.
  • §Of the National Bureau of Standards and University of Colorado, Boulder, Colo.

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Vol. 3, Iss. 6 — June 1971

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