Energy loss of MeV light ions specularly reflected from a SnTe(001) surface

Energy losses of specularly reflected MeV protons and He ions from a clean (001) surface of SnTe single crystal are observed. The position-dependent stopping powers near the surface are derived from the observed results. The obtained stopping power is proportional to $E^{\mathrm{-}1/2}$ exp(-${\beta }_3$x/2$a_{\mathrm{TF})}$, where E is the ion energy, $a_{\mathrm{TF}}$ is the Thomas-Fermi screening distance, ${\beta }_3$ is 0.3, and x is the distance from the surface. This result is similar to the observed position-dependent stopping power for planar channeled ions.