Doublet→quartet and doublet→doublet electronic transitions in NO2 by electron impact

The electron-impact energy-loss spectrum of nitrogen dioxide (NO2) has been measured at impact energies of 25, 50, and 75 eV, and scattering angles varying from 5° to 80°. A previously unreported spin-forbidden doublet→quartet transition was observed at 4.49 eV, in excellent agreement with theoretical calculations. Doublet→doublet transitions were observed at 2.95, 5.81, 7.48, 8.64, 9.69, 10.52, 10.68, 10.94, and 11.20 eV, in agreement with previous experimental and theoretical work. In addition, numerous doublet→doublet transitions to superexcited states were observed.