Regensburg 2007 – scientific programme
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O: Fachverband Oberflächenphysik
O 7: Metal Substrates: Adsorption I
O 7.5: Talk
Monday, March 26, 2007, 12:15–12:30, H39
Enhanced erosion rate by adsorbates in grazing incidence ion bombardment applications — •Alex Redinger1 and Thomas Michely2 — 1I. Physikalisches Institut, RWTH Aachen University, 52056 Aachen, Germany — 2II. Physikalisches Institut, Universität Köln, 50937 Köln, Germany
Noble gas ion bombardment not only causes erosion, but is also known to efficiently remove adsorbates from the retracting surface. However, little is known about the interaction between the impinging ions and the adsorbates and its consequences for the eroding surface. In order to gain more insight into the effects the surface morphology of Pt(111) was investigated by scanning tunneling microscopy after 5 keV Ar+ ion bombardment at an angle of 83∘ to the surface normal. During the ion bombardment at 550 K the substrate has been exposed to different oxygen partial pressures. At 550 K oxygen adsorbs dissociatively on Pt(111) with a small sticking probability. The analysis shows that for small ion fluences the amount of removed material varies by an order of magnitude in dependence of the oxygen partial pressure. Subsequent annealing experiments were performed to take into account the subsurface damage. The origin of the dependence of the erosion rate on oxygen partial pressure is traced back to an adsorbate induced suppression of surface channeling.