Light emission induced from projectiles of H+, H2+, and H3+ interacting with N2, N2O, and O2

When energetic protons and hydrogen molecular ions interact with several different gases (i.e., N2, N2O, and O2), excited hydrogen atoms are produced that release Balmer-series radiation. Balmer-β and -γ radiations thus produced with beam energies ranging from 3 to 10 keV and scanned wavelengths ranging from 3000 to 6000 A are detected and analyzed. The velocity of projectiles is considered as the most important factor that influences the emission cross section of Balmer radiations. Under different bombarding conditions, the data indicate the following three characteristics: (a) Given the same gas target and the same beam energy, the magnitude of the light emission varies with different projectiles according to the following order: H3+>H2+>H+; (b) independent of the incident ion, the largest emission cross section for the Balmer radiation is induced by oxygen gas and the smallest by nitrogen gas; (c) the emission cross sections of all Balmer radiations are inversely proportional to the beam energy. A striking feature is observed: the emission cross section for the Balmer radiation depends only on the velocity of the incident ion. Namely, the cross sections for, say, incident ions H+, H2+, and H3+ with incident energies E1, 2E1, and 3E1, respectively, are the same. A velocity model is used to describe this phenomenon: Upon approaching a gas molecule X, the incident proton or the proton fragment of the incident molecule ion will form a temporary compound (H++X) with the target. The proton will capture an electron from the target and leave the compound in an excited state of the hydrogen atom. An electron-promotion model is suggested for the interaction