Accelerated Molecular Dynamics of Temperature-Programmed Desorption

Kristen A. Fichthorn (Penn State University), DMR 0514336

Temperature-programmed desorption (TPD) is the most widely used experimental technique for measuring the binding energy of a molecule to a solid surface. TPD involves adsorbing gas-phase molecules to a solid surface, heating the surface over time, and analyzing the spectrum of molecules that desorb as a function of temperature / time. Despite its wide use, the interpretation of TPD can be difficult.We developed an accelerated molecular dynamics method that can simulate TPD over experimental times, up to minutes. These are the first real-space and real-time models of TPD and they show how spectra that seem to obey simple, text-book models can arise from a complex interplay of molecular configurations and interactions not envisioned in simple models. Our work will enable accurate extraction of kinetic data from TPD experiments.

Simulated TPD spectrum, indicating the molecular configurations of n-pentane molecules on the graphite surface.

International Summer School on Surfaces and Nanoscale Materials

Kristen A. Fichthorn (Penn State), DMR 0514336

In collaboration with Prof.-Dr. Matthias Scheffler (Fritz-Haber-Institut der Max-Planck-Gesellschaft, Germany), Kristen Fichthorn organized the International Summer School “Modern Concepts for Creating and Analyzing Surfaces and Nanoscale Materials”, which took place in Sant Feliu de Guixols, Costa Brava, Spain in May 2008.The summer school gathered leading theoretical and experimental researchers in materials science to review recent advances in materials simulations in light of topical, material-specific problems and experimental findings. A group of about 60 graduate students, postdocs, junior faculty from physics, chemistry, engineering, and materials science participated. The school received support from the Marie-Curie Psi-k training fund, CECAM, IDECAT, the US Air Force, and the NSF.

Graduate Student Finalists in the Young ResearcherCompetition from Left to Right: Julius G. O. Ojwang(NL), Rajesh Sathiyanarayanan (USA), GregorHlawacek (AT), Jessica Bickel (USA), MarinaLeite (BR), Kristen Fichthorn (Organizer, USA)