LOW-ENERGY-ELECTRON IMPACT EXCITATION OF THE NITROGEN MOLECULE - OPTICALLY FORBIDDEN TRANSITIONS

Ab initio calculations are performed on the e(-)-N-2 scattering system , at low impact energies, using the R-matrix technique. The X (1) Sigm a(g)(+) ground state and the lowest seven valence excited states, A (3 ) Sigma(u)(+), B (3) Pi(g), W (3) Delta(u), B' (3) Sigma(u)(-), a' (1) Sigma(u)(-), a (1) Pi(g) and w (1) Delta(u), of N-2 are included in t he close coupling expansion with each state being represented by a con figuration interaction wavefunction in a hybrid orbital set. Various a pproximations for the representation of the correlation between the ta rget and the incident electron are investigated. Integrated and differ ential scattering cross sections are presented, and compared to experi ment, for excitation from the ground level to optically forbidden leve ls. The results compare favourably with recent experiments in this ene rgy region and remove a number of problems with our previous work.