Intensity distributions in nitrogen bands excited in auroras and by high‐energy protons and hydrogen atoms

Nitrogen negative and second positive band spectra have been excited by 100‐kv protons and hydrogen atoms from the Rice Institute van de Graaff accelerator. The intensity distributions in the vibrational bands are compared with spectra produced in controlled laboratory experiments by canal rays and electron impact, with auroral spectra, and with results of theoretical calculations. Excitation of second positive bands by high‐energy neutral hydrogen atoms and of the negative bands by both neutral hydrogen and protons show the expected marked increase in the rate of population of high vibrational states. Theories for the excitation of the auroral bands are discussed in the light of these results and of theoretical considerations.