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Issue A&A Volume 500, Number 3, June IV 2009 Page(s) 1253 - 1261 Section Atomic, molecular, and nuclear data DOI 10.1051/0004-6361/200911743 Published online 16 April 2009

A&A 500, 1253-1261 (2009)
DOI: 10.1051/0004-6361/200911743

Electron-impact excitation of Ar²⁺

J. M. Munoz Burgos, S. D. Loch, C. P. Ballance, and R. F. Boivin

Department of Physics, Auburn University, Auburn, AL 36849, USA
    e-mail: munozjm@auburn.edu

Received 28 January 2009 / Accepted 12 March 2009

Abstract
Context. Emission from Ar III is seen in planetary nebulae, in H II regions, and from laboratory plasmas. The analysis of such spectra requires accurate electron impact excitation data.
Aims. The aim of this work is to improve the electron impact excitation data available for Ar²⁺, for application in studies of planetary nebulae and laboratory plasma spectra. The effects of the new data on diagnostic line ratios are also studied.
Methods. Electron-impact excitation collision strengths have been calculated using the R-Matrix Intermediate-Coupling Frame-Transformation method and the R-Matrix Breit-Pauli method. Excitation cross sections are calculated between all levels of the configurations 3s²3p⁴, 3s3p⁵, 3p⁶, 3p⁵3d, and 3s²3p³nl (3d  nl  5s). Maxwellian effective collision strengths are generated from the collision strength data.
Results. Good agreement is found in the collision strengths calculated using the two R-Matrix methods. The collision strengths are compared with literature values for transitions within the 3s²3p⁴ configuration. The new data has a small effect on values obtained from the I(7135 Å+ 7751 Å)/ I(5192 Å) line ratio, and a larger effect on the values obtained from the I(7135 Å)/I(9 m) line ratio. The final effective collision strength data is archived online.


Key words: atomic data -- atomic processes -- ISM: planetary nebulae: general

© ESO 2009

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