Dresden 2003 – wissenschaftliches Programm
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O: Oberflächenphysik
O 24: Postersitzung (Epitaxie und Wachstum, Oxide und Isolatoren, Elektronische Struktur, Oberfl
ächenreaktionen, Adsorption an Oberfl
ächen, Organische Dünnschichten)
O 24.64: Poster
Mittwoch, 26. März 2003, 14:30–17:30, P1
Simulation of non-ideal thermal desorption — •Bernhard Lehner, Michael Hohage, and Peter Zeppenfeld — Institut für Experimentalphysik, Abteilung Atom- und Oberflächenphysik, Johannes Kepler Universität Linz
We have developed a novel Kinetic Monte Carlo (KMC) Simulation scheme, capable of reproducing adsorption and desorption phenomena, structure growth and adsorbate phase transitions on crystal surfaces. Whereas KMC is known as a powerful tool for studying adsorption problems, its application to desorption phenomena is a new challenge. The program allows to link an experimentally observed (macroscopic) desorption behaviour to the underlying atomic or molecular (microscopic) processes, which are well understood by theory. Thus, the KMC can assist in getting insight to a large variety of desorption phenomena: Ideal (2D-quasi equilibrium) desorption situations can be investigated as well as non-ideal phenomena occurring due to kinetic constraints, weak lateral adsorbate-adsorbate interactions, substrate inhomogenities or long ranged/multi-body interactions. The non-ideal temperature programmed desorption (TPD) spectra of Xe/Pt(111), Xe/Pt(997), N2/Cu(110)-(2×1)O and CF4 on the Cu-CuO stripe phase have been quantitatively reproduced by the KMC. The KMC reveals the importance of kinetic effects, adsorbate phase transitions, substrate steps and finite terrace-width effects on the desorption behaviors of the aforementioned systems.