Absolute cross sections for 2s-2p excitation of N4+ by electron impact

Absolute cross sections have been measured for 1s22s 2S/sub 1/2/-1s22p 2P/sub 1/2,3/2/ excitation of lithiumlike N4+ 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 C3+ 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 N4+ transition