Fine structure effective collision strengths for the electron impact excitation of Al III

Abstract

Abstract.A 10-state R-matrix calculation has been carried out to generate fine structure effective collision strengths for the electron impact excitation of doubly ionized aluminium. The target states are represented by configuration interaction wavefunctions and consist of the 10 lowest LS states -(2p 6 )3s, 3p, ..., 5p, 5d. These 10 target states give rise to 17 fine structure levels and 136 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 for transitions between both the LS states and the fine structure levels are given for electron temperatures (T e ) in the range log 10 T e (K) = 3.6−5.6. Comparisons are made with previous calculations and we find good agreement with the work of Kimura et al. (1998).

R-matrix electron-impact excitation data for the Na-like iso-electronic sequence

“…3 (only decays to the 5 lowest-lying levels are shown). For Al 2+ , the present results agree to within 20% when compared with those available from Hudson & Bell (2005) and NIST's v.3 compilation. For Fe 15+ , a complete set of data from Aggarwal & Keenan (2006) is available and so more transitions are compared.…”

“…As shown in Fig. 4a, Hudson & Bell (2005). Middle: Fe 15+ ; EGM99 refers to the Breit-Pauli R-matrix results of Eissner et al (1999) and AK06 to the Dirac R-matrix results of Aggarwal & Keenan (2006).…”

“…R-matrix results of Hudson & Bell (2005) and Aggarwal & Keenan (2006), respectively. Moreover, there is no sudden jump in the present ordinary Ω (see Fig.…”

“…Thereafter, more elaborate calculations have been performed for several ions. For example, Eissner et al (1999) presented Breit-Pauli R-matrix results for electron-impact excitations amongst the 12 fine-structure levels of the n ≤ 4 configurations of Fe 15+ ; Hudson & Bell (2005) reported R-matrix results for level-resolved excitations among the lowest 17 finestructure levels belonging to 3l, 4l, 5s, 5p and 5d configurations of Al 2+ by re-coupling LS-coupling results via the jajom code; Aggarwal & Keenan (2006) reported results for level-resolved excitations among the lowest 39 levels amongst the n ≤ 7 (l ≤ 4) configurations of Fe 15+ by using the Dirac atomic R-matrix code darc.…”