Dresden 2009 – scientific programme

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O: Fachverband Oberflächenphysik

O 29: Nanostructures at surfaces: preparation

O 29.6: Talk

Wednesday, March 25, 2009, 11:45–12:00, SCH A01

Surface vacancy channels through ion channeling — •Alex Redinger¹, Sebastian Standop¹, Yudi Rosandi², Herbert M. Urbassek², and Thomas Michely¹ — ¹II. Physikalisches Institut, Universität zu Köln, Zülpicher Strasse 77, 50937 Köln, Germany — ²Fachbereich Physik, Technische Universität Kaiserslautern, Erwin-Schrödinger-Straße, D-67663 Kaiserslautern, Germany

Damage patterns of single ion impacts on Pt(111) have been studied by scanning tunneling microscopy (STM) and molecular dynamics simulations (MD). Low temperature experiments, where surface diffusion is absent, have been performed for Argon and Xenon ions with energies between 1 keV and 15 keV at an angle of incidence of 86^∘ measured with respect to the surface normal. Ions hitting preexisting illuminated step edges penetrate into the crystal and are guided in open crystallographic directions, one or more layers underneath the surface (subsurface channeling). In the case of Argon channeling the resulting surface damage consists of adatom and vacancy pairs aligned in ion beam direction. After Xenon channeling thin surface vacancy trenches along the ion trajectories - surface vacancy channels - are observed. They result from very efficient sputtering and adatom production along the ion trajectory. This phenomena is well reproduced in molecular dynamics simulations of single ion impacts at 0 K. The damage patterns of Argon and Xenon impacts can be traced back to the different energy losses of the particles in the channel. Channeling distances exceeding 1000 Å for 15 keV Xenon impacts are observed.