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Paper III


Rate coefficients for electron-impact excitation of boron-like ions
- Ne-VI, Mg-VIII, Al-IX, Si-X, S-XII, Ar-XIV, Ca-XVI and Fe-XXII
 
Zhang.HL, Graziani.M, Pradhan.AK
Astronomy & Astrophysics, 1994, Vol.283, No.1, pp.319-330

Collision strengths and maxwellian averaged rate coefficients have been calculated for the 105 transitions among all 15 fine structure levels of the 8 LS terms 2s2 2p(P-2(1/2.3/2)0), 2s2p2(P-4(1/2,3/2,5/2, 2D3/2,5/2, S-2(1/2, P-2(1/2,3/2)), 2p3(S-4(3/2)0, 2D3/2,5/2(0), P-2(1/2,3/2)0) in highly-charged B-like Ne, Mg, Al, Si, S, Ar, Ca and Fe. Rate coefficients have been tabulated at a wide range of temperatures, depending on the ion charge and abundance in plasma sources. Earlier work for O IV (Blum & Pradhan 1992) has also been extended to include the high temperature range. A brief discussion of the calculations, sample results, and comparison with earlier works is also given. While much of the new data should be applicable to UV spectral diagnostics, the new rates for the important ground state fine structure transition P1/2-2(0)-P-2(3/2)0 should result in significant revision of the IR cooling rates in plasmas where B-like ions are prominent constituents, since the new rate coefficients are generally higher by several factors compared with the older data.


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2006-10-25