Hamburg 2001 – wissenschaftliches Programm
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O: Oberflächenphysik
O 13: Postersitzung (Adsorption auf Oberfl
ächen, Oberfl
ächenreaktionen, Elektronische Struktur, Epitaxie und Wachstum, Halbleiteroberfl
ächen und Grenzfl
ächen, Oxide und Isolatoren)
O 13.12: Poster
Montag, 26. März 2001, 19:00–22:00, Foyer zu B
Monte Carlo simulation of the adsorbate assisted adsorption. — •U. Burghaus1, L. Vattuone2 und I. Kobal3 — 1PC I, Ruhr-Uni.-Bochum,burghaus@pc.ruhr-uni-bochum.de — 2INFM-CFSBT del CNR, Di. di Fisica, Uni. di Genova — 3J.Stefan Inst., Ljubljana, Slovenia
Adsorption probabilities, S, are one of the main sources to gain information about the dynamics of gas-surface interactions and lateral interactions, Eij. A simple way to contribute to this topic are Monte Carlo simulations (MCS) of the coverage, Θ, dependence of S. MCS can account for both dynamic (effect of impact energy, E0) and kinetic (Eij) effects, respectively. A common observation is an increase in S with Θ (adsorbate assisted adsorption). It has been shown (e.g. [1]) that the effect is most distict at high E0 and low surface temperature, Ts. Low Ts are a pre-requisite for large Θ, indicating an extrinsic precursor. The importance of high E0 suggests a dynamic effect rather than Θ dependent kinetics. If a particle hits an occupied site, S will be larger as compared to adsorption on a clean site because of the improvement in the mass-mismatch. Therefore in the 1st case the energy transfer will be more efficient; S will be larger as in the latter case. According to the different impact scenarios it is possible to simulate the increase in S with Θ by assuming only different S in MCS [1]. However, Eij certainly have an effect on details of S(Θ). The MCS algorithm will be discussed by synthetic examples [2] and by qualitative fits of experimental data (CO/ZnO [1]).
[1] T. Becker, et al., JCP 113 (2000) 6334
[2] U. Burghaus, et al., Proc. 9th Int. Symp. on Catal., Varna, 2000.