Kl. Bell et al., Electron collisional excitation of Si (VIII): (1s(2)2s(2)2p(3) S-4(3/2)o, D-2(3/2,5/2)o, P-2(1/2,3/2)o) fine-structure transitions, M NOT R AST, 322(4), 2001, pp. 779-784
Effective collision strengths for electron-impact excitation of the N-like
ion Si VIII are calculated in the close-coupling approximation using the ab
initio R-matrix method. The 22 fine-structure levels arising from the 11 l
owest LS target states: 2s(2)2p3, 2S2p(4), 2p(5) and 2s(2)2p(2)3s are retai
ned in the present calculation. The effective collision strengths for all f
orbidden transitions within the 1s(2)2s(2)2p(3) S-4(3/2)o, D-2(3/2.5/2)o, P
-2(1/2.3/2)o ground configuration levels are obtained by averaging the elec
tron collision strengths, for a wide range of incident electron energies, o
ver a Maxwellian distribution of velocities. Results are presented for elec
tron temperatures in the range log T(K) = 3.3 to log T(K) = 6.5, applicable
to many laboratory plasmas and in particular to astrophysical plasmas. We
believe that the results are the most accurate to date and, indeed, the onl
y data available which take account of resonance effects.