Effective collision strengths for fine-structure transitions for the electron impact excitation of N II^*

Department of Applied Mathematics and Theoretical Physics, The Queens University of Belfast, Belfast BT7 1NN, Northern Ireland, UK e-mail: c.hudson@am.qub.ac.uk

Received: 7 September 2004
Accepted: 28 September 2004

Abstract

We present effective collision strengths for the electron impact excitation of singly ionized nitrogen which have been calculated using the R-matrix method. The 23 lowest LS states are included in the expansion of the total wavefunction. These target states arise from the 2s²2p², 2s2p³ and 2s²2p3l( configurations, leading to 41 fine structure levels and 820 possible transitions. The fine-structure collision strengths were obtained by transforming to a jj-coupling scheme using the JAJOM program of Saraph and have been determined at a sufficiently fine energy mesh to delineate properly the resonance structure. The effective collision strengths were calculated by averaging the electron collision strengths over a Maxwellian distribution of velocities. Tabulations of the non-zero effective collision strengths are given for electron temperatures (T_e) in the range .