ABSOLUTE CROSS-SECTIONS FOR 2S-2P EXCITATION OF N4+ BY ELECTRON-IMPACT

Absolute cross sections have been measured for 1s/sup 2/2s /sup 2/S/sub 1/2/-1s/sup 2/2p /sup 2/P/sub 1/2,3/2/ excitation of lithiumlike N/sup 4 +/ by electron impact. For this process, which has a threshold at 10 eV, relative cross sections measured at several energies between 4 and 52 eV were normalized to a single absolute measurement taken at 15.5 eV. Similar data for Li-like C/sup 3 +/ have been previously reported and are presented for comparison. In both cases, allowing for the experimental electron energy spread, the measurements agree within experimental uncertainties with published Coulomb-Born and close-coupling calculations over the entire experimental energy range. Rate coefficients as a function of electron temperature are also presented for the N/sup 4 +/ transition.