PROTON EXCITATION OF THE 2s2 2p5 2 P3/2 -2s22p5 2P1/2 TRANSITION IN FLUORINE-LIKE Ti XIV and Ni XX

Rate coefficients for excitation of the 2s22p5 2P3/2 - 2s22p5 2P1/2 transition in fluorine-like Ti XIV and Ni XX by proton impact have been calculated using the close-coupled impact parameter method. These data are significantly different from earlier results with, for example, our proton rates for Ti XIV being approximately a factor of five smaller than those of Bely and Faucher (1970) at low temperatures. We show that the 2s22p5 2P3/2 - 2s22p5 2P1/2 transition in Ti XIV and Ni XX may be used to infer the electron density or ion temperature of a laboratory plasma through the diagnostic emission line ratios R1 = I(2s22p5 2P3/2 - 2 s22P52P1/2)/I(2s22P52P3/2 - 2s2p6 2S1/2) and R2 = I(2s22p5 2P3/2 - 2s22p5 2P1/2)/I(2s22p52P1/2 - 2s2p6 2S1/2), although the theoretical values of R1 and R2 are strongly dependant on the magnitude of the proton excitation rate for 2s22p5 2P3/2 - 2s22p5 2P1/2. The accurate calculation of this quantity for Ti XIV and Ni XX is therefore of great importance