Electron-impact excitation cross sections of theaΠg1of theN2molecule by the close-coupling method

Electron-impact excitation cross sections of the $a{}_{}{}^1{}_{}{}^{}\Pi _g^{}{}_{}{}^{}$ state of the ${\mathrm{N}}_2$ molecule are calculated by the method of close coupling with full allowance for electron exchange for incident-electron energies of 12.5-50 eV. The wave functions of the two states involved are calculated by the self-consistent-field method with ten $s$-type and six $p$-type Gaussian orbitals as basis functions. The present calculation agrees very well with experiments above 30 eV, but a substantial difference is found below 30 eV.