Measurements ofQValues forN+-Ar andO+-Kr Collisions by the Coincidence Technique

Abstract

Inelastic energy ($Q$) profiles and ionization probabilities are measured for ${\mathrm{N}}^{+}$-Ar and ${\mathrm{O}}^{+}$-Kr collisions using the coincidence techniques of Kessel and Everhart. Incident-ion energies from 10 to 150 keV and scattering angles from 9\ifmmode^\circ\else\textdegree\fi{} to 40\ifmmode^\circ\else\textdegree\fi{} for ${\mathrm{N}}^{+}$-Ar collisions, and from 25 to 230 keV and 10\ifmmode^\circ\else\textdegree\fi{} to 40\ifmmode^\circ\else\textdegree\fi{} for ${\mathrm{O}}^{+}$-Kr collisions, are studied. The range of average $Q$ values ($\overline{Q}$) is from about 100 eV to about 1 keV for both cases. The average number of electrons lost in the collision varies from about 0.6 to 1.3 for nitrogen and from 3.3 to 4.6 for argon in the ${\mathrm{N}}^{+}$-Ar collisions. For the ${\mathrm{O}}^{+}$-Kr collisions, the ranges are zero to 1.7 and 2.6 to 6.6 for oxygen and Kr, respectively. For ${\mathrm{N}}^{+}$-Ar collisions, a plot of $\overline{Q}$ versus the distance of closest approach shows an abrupt increase of about 115 eV at about 0.15 \AA{}. A study of the natural linewidths of the coincidence profiles indicates the presence of unresolved structure in this vicinity. For the ${\mathrm{O}}^{+}$-Kr collisions, $\overline{Q}$ was found to depend on both the distance of closest approach and the collision velocity, but not strongly on the scattering angle at higher energies.