Excitation of K*(3p54s22P3/2,2P1/2) by electron impact in the range from near threshold to 500 eV: alignment and cross section ratios

We have measured the alignment A 20 of K*(3p 5 4s 2 2 P 3/2 ) and the ratio of cross sections R 0 = sigma (3/2)/ sigma (1/2) of fine structure states K*(3p 5 4s 2 2 P 3/2 , 2 P 1/2 ) for electron impact excitation in the range of incident energy E 0 = 31.4-500 eV. We have also calculated these quantities in the distorted wave Born approximation (DWBA) and the plane wave Born approximation (PWBA). There is good agreement between experiment and the present DWBA and PWBA values for the alignment A 20 whereas earlier DWBA values by Pangantiwar and Srivastava (1987) deviate systematically from experiment for E 0 < 100 eV. For the ratio of cross sections R 0 the present DWBA values agree only qualitatively with the experiment for E 0 < 100 eV.