Berlin 2001 – wissenschaftliches Programm
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A: Atomphysik
A 17: Posters Friday (Spectroscopy)
A 17.21: Poster
Freitag, 6. April 2001, 12:30–15:00, AT3
Line-Mixing in H broadening of the Na 3d-3p Lines — •J Sanchez-Fortún Stoker and A S Dickinson — Physics Department, University of Newcastle upon Tyne, NEWCASTLE upon TYNE, NE1 7RU, UK
Spectral line broadening due to collisions with hydrogen atoms is the major broadening mechanism for metallic lines in the sun and in stars of comparable temperature. One of the lines of observational interest is the Na 3 2D - 3 2P multiplet. Calculations using the impact approximation of the H broadening of these 3 lines [1] showed differences in their widths of no more than 5%. However, modelling of the solar spectrum [2] suggests differences of a factor of two between the width of the 2D3/2 - 2P1/2 line and the unresolved doublet 2DJ - 2P3/2. It is difficult to see how the relevant NaH potentials for Na(3d/3p)+H(1s) could lead to such large differences in widths. Hence, as the 3 2DJ fine-structure levels are separated by only 0.050 cm−1, we are investigating, within the impact approximation, the importance of line-mixing between these two lines at number densities ≈ 10−17 cm−3, typical of those in the solar atmosphere. Results will be presented at the meeting.
[1] T. Leininger, F. X. Gadéa and A. S. Dickinson, J. Phys. B 33, 1805 (2000)
[2] G. Smith, private communication (2000)