Ion emission due to the scattering of hyperthermal Xe atoms from single crystal surfaces.

We report the emission of ions from single crystal surfaces due to the scattering of hyperthermal Xe over the energy range 6 E sub i (eV) 20. We observe Ga sup + form GaAs(110), In sup + form InP(100), and alkali and other impurity ions from all surfaces. At E sub i = 16 eV the ion emission probability for In sup + reaches 1 x 10 sup (-3). The yields increase as the Xe incident angle goes towards grazing, have a similar Xe kinetic energy dependence, and a common threshold near 6. 5 eV at the incident angles of maximum efficiency. We discuss possible mechanisms for ion emission.