Laboratory Ionic-Impact Emission Spectra.

A spectrographic study has been made of the optical emissions from a rarefied air sample under the bombardment of protons (4( 23O kev), deuterons ( kev), He+ ions (150450 kev), and Ne+ ions (400 kev). It was found that the ratio of intensity between the N ii and N2+ emissions is a proximately independent of the energies of the bombarding particles but strongly dependent upon t e species of particle. As a consequence it is found to be possible to distinguish between protons and heavy ions by the spectrum produced, even when emissions from the exciting particle are absent. This discovery has made it possible to estimate the ratio of protons to heavies in the primary particle beam producing the aurora borealis.