Direct evidence of the surface track potential

Abstract

Angular and energy distributions of fragment protons dissociated from HeH + during grazing-angle scattering from a KCl (001) surface are measured. The surface of KCl (001) is heated at 180 • C and the beam current is kept lower than 1 fA to prevent macroscopic surface charging. The angular distribution of the fragment protons shows a well-defined peak similarly to the grazing-angle scattering of atomic ions. The observed peak, however, is shifted from the specular angle toward larger scattering angles. The observed angular shift for the trailing proton is larger than that for the leading proton. These results clearly indicate that the motion of the fragment protons is affected by the surface track potential induced by the partner He ion.

Grazing scattering of 1–2MeV HeH+ ions from KCl(001): Effect of surface track potential

“…In our previous paper, we used a simple model to describe the surface track potential [10]. In the model, the position-dependent hole production rate was estimated using a local density binary encounter model.…”

“…Other probing methods compatible with low beam current far below 1 pA are absolutely necessary for the detailed study on the surface track potential. Recently, we have demonstrated that HeH + ion can be used to study the surface track potential [10]. The two dimensional distributions (energy and scattering angle distributions) of fragment protons dissociated from 1-MeV HeH + during grazing angle scattering at KCl(0 0 1) were observed.…”