Elastic Differential Scattering ofHe+Ions by Ne and Ar and ofAr+Ions by Ar in the 10-600-eV Range

Abstract

Absolute elastic differential scattering cross sections of ${\mathrm{He}}^{+}$ on Ne and Ar and of ${\mathrm{Ar}}^{+}$ on Ar have been measured at relative energies ranging from 10 to 600 eV and scattering angles of 1\ifmmode^\circ\else\textdegree\fi{} to 40\ifmmode^\circ\else\textdegree\fi{}. The ${\mathrm{He}}^{+}$ on Ne and Ar cross sections are monotonically decreasing functions of angle and have a superimposed ripple structure which is attributed to curve-crossing effects. No rainbow-angle structure is evident on these curves. The ${\mathrm{Ar}}^{+}$-on-Ar cross sections indicate both rainbow scattering and oscillations associated with symmetric charge exchange. From the values of the rainbow scattering angle, the estimated binding energy of $\mathrm{Ar}_{2}^{}{}_{}{}^{+}$ is 1.6\ifmmode\pm\else\textpm\fi{}0.3 eV, assuming the general shape of the attractive potential resembles that of $\mathrm{He}_{2}^{}{}_{}{}^{+}$.