Regensburg 2010 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 60: Poster Session III (Methods: Atomic and electronic structure; Methods: electronic structure theory; Methods: Molecular simulations and statistical mechanics; Methods: Sanning probe techniques; Methods: other (experimental); Methods: other (theory) )
O 60.7: Poster
Mittwoch, 24. März 2010, 17:45–20:30, Poster B2
Atomic charge state determination by AFM — •Leo Gross1, Fabian Mohn1, Peter Liljeroth1, Jascha Repp2, Franz J. Giessibl2, and Gerhard Meyer1 — 1IBM Research - Zurich, 8803 Rüschlikon, Switzerland — 2Institute of Experimental and Applied Physics, University of Regensburg, 93040 Regensburg, Germany
We investigated the charge state switching of individual gold and silver adatoms on ultrathin NaCl films on Cu(111) using a qPlus tuning fork atomic force microscope (AFM) operated at 5 Kelvin with oscillation amplitudes in the sub-Ångstrom regime. Charging of a gold adatom by one electron charge increased the force on the AFM tip by a few piconewtons. Employing Kelvin probe force microscopy (KPFM) we also measured the local contact potential difference (LCPD) as a function of the tip height above differently charged adatoms. We observed that the LCPD is shifted depending on the sign of the charge and allows the discrimination of positively charged, neutral, and negatively charged atoms. [L. Gross, et al., Science 324, 1428 (2009)]