ATOMIC DATA FROM THE IRON PROJECT - XXVIII - ELECTRON-EXCITATION OF THE P-2(3 2)DEGREES-]P-2(1/2)DEGREES FINE-STRUCTURE TRANSITION IN FLUORINE-LIKE IONS AT HIGHER TEMPERATURES/

The collision strength Omega(P-2(3/2)O, P-2(1/2)O) for the fine struct ure transition within the ground term of 17 fluorine-like ions from Mg Iv to Ni XX is calculated using the R-matrix method. We include targe t terms with n = 3 in order to take account of the resonance structure in Omega at energies above 2s2p(6 2)S. These resonances are delineate d using a fine mesh of several thousand energy points to scan the regi on between the first and 27th excited terms. Results from an earlier c alculation (IRON Project Paper IV) are used to cover the region below 2s2p(6) S-2. We make use of the fact that Omega tends to the Born limi t as the collision energy E --> infinity. The effective collision stre ngth Upsilon is tabulated as a function of log T-S, where T-S = T/(Z-8 )(2) is a Z-scaled temperature. We compare results for Si+5, Fe+17 and Ni+19 with those obtained by Mohan and coworkers. An explanation is g iven for the large discrepancy in the case of Upsilon(Si+5).