Emission of Molecular Nitrogen upon Electron Bombardment of Pyrolytic Aerogel SiO 2 and Aluminum

It is found that the emission intensity of the 2+ band system of the N2 molecule (C3Πu → B3Πg transition) under electron bombardment of pyrolytic aerogel SiO2 in air at atmospheric pressure is 40–70% higher than that in the case of bombardment of aluminum under the same conditions. The dependences of the emission intensity at 337 nm (0-0 vibrational transition in the 2+ band system of the N2 molecule) on the target temperature in the range of 30–60°C are different for the aluminum and SiO2 targets, which indicates different excitation mechanisms of the N2(C3Πu) state. It is suggested that when the SiO2 target is bombarded, the N2(C3Πu) state is excited not only by direct collisions with the electrons of the primary beam and secondary electrons, but also by the energy transfer from SiO2 excitons and conduction electrons to N2 molecules upon their contact with the SiO2 surface.