Regensburg 2004 – scientific programme

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O: Oberflächenphysik

O 23: Rastersondentechniken II

O 23.3: Talk

Tuesday, March 9, 2004, 16:15–16:30, H36

Local interfacial dipoles of alkali chloride thin films on Au(111) investigated with Kelvin probe force microscopy — •Ulrich Zerweck, Christian Loppacher, Stefan Grafström, and Lukas M. Eng — Institute of Applied Photophysics, University of Technology, D-01062 Dresden

Interface dipole formation of alkali chloride thin films on Au(111) is investigated under ultrahigh vacuum conditions at room temperature by noncontact atomic force microscopy in combination with Kelvin-probe force microscopy (KPFM). Sample preparation is carried out in-situ and optimized in order to achieve a sub-monolayer coverage on Au(111) with extended alkali chloride islands.
 The local surface potential for LiCl, NaCl, KCl, and RbCl thin films on Au(111) was determined by KPFM, with the bare Au(111) substrate serving as a reference. We thus directly probe the local and absolute change in the work function ΔΦ which is found to vary linearly as a function of the radius of the alkali ion. Furthermore, good agreement was obtained when checking our KPFM measurements with ultraviolet photoemission spectroscopy on a larger scale.