Dresden 2003 – wissenschaftliches Programm
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O: Oberflächenphysik
O 21: Adsorption an Oberfl
ächen II
O 21.5: Vortrag
Dienstag, 25. März 2003, 16:00–16:15, HSZ/03
The influence of weak adsorbate-adsorbate interactions on desorption — •Bernhard Lehner, Michael Hohage, and Peter Zeppenfeld — Institut für Experimentalphysik, Abteilung Atom- und Oberflächenphysik, Johannes Kepler Universität Linz
Physisorbates on metal or semiconductor substrates often exhibit only weak lateral adsorbate-adsorbate interactions. We have studied the influence of such weak interactions on submonolayer thermal desorption spectra (TDS) using a comprehensively tested novel Kinetic Monte Carlo Simulation. It is shown, that the desorption order continuously changes from zero to first to second order like behaviour when decreasing the adsorbate-adsorbate binding energy from positive (attractive) to negative (repulsive) values. The desorption of N2 on Cu(110)-(2×1)O and Xe on Pt(111) provide examples for systems crucially influenced by weak lateral interactions. While standard methods of analysis of temperature programmed desorption (TPD) spectra (such as those proposed by King or Falconer and Madix) fail, the experimental TPD curves of both systems are quantitatively reproduced by Kinetic Monte Carlo Simulations.