Alignment of Ionic Ground State of Xe by Electron-Impact Ionization Observed through Exchange Collision with the Neutral Metastable State

Abstract

The radio-frequency paramagnetic-resonance method was used to observe the exchange collisions between the singly ionized Xe ground state ${}_{}{}^2{}_{}{}^{}P_{\frac{3}{2}}^{}{}_{}{}^{}$ and the neutral metastable state ${}_{}{}^3{}_{}{}^{}P_2^{}{}_{}{}^{}$. The ionic ground-state and metastable-state atoms are both formed and aligned by unidirectional low-energy high-flux electron-beam impact. The magnetic resonances of even and odd ionic ground-state atoms were observed by monitoring changes in the transparency of the resonance radiation absorbed by the metastable-state atoms. Phenomenological theories are presented which explain the sign of the magnetic-resonance signal of the ionic ground state relative to that of the neutral metastable state, together with independent experimental evidence to support the theories. Conclusive experimental evidence is presented supporting our original assumptions that the ionic ground-state ${\mathrm{Xe}}^{+}\left({}_{}{}^2{}_{}{}^{}P_{\frac{3}{2}}^{}{}_{}{}^{}\right)$ is aligned by low-energy electron-impact ionization and that such alignment is detectable through the results of exchange collisions with the metastable state.