We use molecular-dynamics simulations and importance sampling to obtain transition-state theory rate constants for thermal desorption of an n-alkane series from Pt(111). These simulations indicate that the binding of a large molecule to a solid surface is a complex phenomenon involving many local minima. The existence of local minima invalidates the interpretation of thermal desorption as a single, ﬁrst-order rate process. Because the number of local minima increases with increasing chain length, n-alkane adsorption becomes increasingly dominated by entropy for longer chains. Consequently, the binding energy increases in a less-than linear way with increasing chain length. Our results provide a quantitative explanation for results and trends in recent experimental studies.
Journal: TechConnect Briefs
Volume: 2, Technical Proceedings of the 2002 International Conference on Computational Nanoscience and Nanotechnology
Published: April 22, 2002
Pages: 156 - 158
Industry sector: Advanced Materials & Manufacturing
Topic: Informatics, Modeling & Simulation