Investigation of the Wigner Spin Rule in Collisions of N+ with He, Ne, Ar, N2, and O2

Abstract

The Wigner electron-spin-conservation rule has been investigated in collisions of 1.5-3.5-keV ${\mathrm{N}}^{+}$ with He, Ne, Ar, ${\mathrm{N}}_2$, and ${\mathrm{O}}_2$ by the technique of ion-impact energy-loss spectrometry. Inelastic and superelastic collisions involving both ground-state and metastable ${\mathrm{N}}^{+}$ have been observed in the energy-loss spectrum between -2.1 and 4.1 eV. The intensities of many of these transitions have been measured and the beam composition and transition cross sections have been determined. In collisions of ${\mathrm{N}}^{+}$ with the singlet-state targets, spin-conservative transitions are nearly three orders of magnitude more probable than spin-nonconservative transitions. In the ${\mathrm{N}}^{+}$-${\mathrm{O}}_2$ collisions there is some evidence that the Wigner rule does not hold as well as in less complex collisions.