Electron-impact excitation of the x ¹Σ_g^-, y ¹Π_g, and o₃ ¹Π_u Rydberg electronic states of the nitrogen molecule

Electron-impact excitation of the x ¹Σ_g^-, y ¹Π_g, and o₃ ¹Π_u Rydberg electronic states of the nitrogen molecule has been studied. We have measured the maximum electron-impact optical-emission cross sections of many vibrational bands of the y ¹Π_g→w ¹Δ_u, y ¹Π_g→a’ ¹Σ_u^-, and x ¹Σ_g^-→a’ ¹Σ_u^- electronic transitions. The maximum values of the optical-emission cross sections of these band systems are typically less than or on the order of 10^-20 cm². The dependence of the emission cross sections of selected bands on electron energy has been studied. The excitation functions of the y→a’ and x→a’ bands have similar shapes below about 50 eV with a peak near 32 eV, and are approximately proportional to 1/E at high energies. We have measured the emission cross section of the o₃ ¹Π_u→a ¹Π_g(0,0) band as a function of electron energy. The excitation function of the o₃→a(0,0) band has a broader shape than the excitation functions of the y→w, y→a’, and x→a’ bands. We have calculated Franck-Condon factors for the y→w, y→a’, and x→a’ band systems and compare them with the experimental emission cross sections of these band systems. The apparent electron-impact-excitation cross sections of the vibrational levels of the x and y electronic states are estimated.