Laboratory data are used to argue that the excitation of the N II doublet near 2145 ¿ by electron impact on N2 occurs through the ejection of an electron from the 2s&sgr;g orbital. The cross section probably exceeds 10-18 cm2, as is required if electron impact excitation of N2 is the source of the auroral feature. By extrapolation along the isoelectronic sequence, we estimate a lifetime of 5.8 ms, in harmony with recent ab initio calculations. The auroral observations then imply a rate coefficient for quenching of N+(5So2) ions in the atmosphere of less than 10-10 cm3 s-1.