Collisional broadening of alkali doublets by helium perturbers

Mullamphy, D.F.T., Peach, G., Venturi, V., Whittingham, I.B., and Gibson, S.J. (2007) Collisional broadening of alkali doublets by helium perturbers. Journal of Physics B: Atomic, Molecular and Optical Physics, 40 (6). pp. 1141-1152.

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We report results for the Lorentzian profiles of the Li I, Na I and K I doublets and the Na I subordinate doublet broadened by helium perturbers for temperatures up to 3000 K. They have been obtained from a fully quantum-mechanical close-coupling description of the colliding atoms, the Baranger theory of line shapes and new ab initio potentials for the alkali–helium interaction. For all lines except the 769.9 nm K I line, the temperature dependence of the widths over the range 70 ≤ T ≤ 3000 K is accurately represented by the power law form w = aTbb with 0.38 < b < 0.43. The 769.9 nm K I line has this form for 500 ≤ T ≤ 3000 K with b having the higher value of 0.49. Although the shifts have a more complex temperature dependence, they all have the general feature of increasing with temperature above T ~ 500 K apart from the 769.9 K I line whose shift decreases with temperature.

Item ID: 2586
Item Type: Article (Research - C1)
ISSN: 1361-6455
Keywords: brown dwarf; alkali resonance doublets; spectral linebroadening
Date Deposited: 06 May 2009 22:55
FoR Codes: 02 PHYSICAL SCIENCES > 0202 Atomic, Molecular, Nuclear, Particle and Plasma Physics > 020201 Atomic and Molecular Physics @ 70%
02 PHYSICAL SCIENCES > 0299 Other Physical Sciences > 029999 Physical Sciences not elsewhere classified @ 30%
SEO Codes: 97 EXPANDING KNOWLEDGE > 970102 Expanding Knowledge in the Physical Sciences @ 100%
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