Topic：Old Fashioned Surface Science in Nanosynthesis

Speaker：Prof. Hanchen Huang

　　　　Department of Mechanical Engineering　　
　　　　　　University of Connecticut, USA　　　　　　　

Time：9:30-11:30, (Thu.) 10, June 2010

Venue：Room 468, Lee Hsun Building

Welcome to attend!

Old Fashioned Surface Science in Nanosynthesis

Hanchen Huang

University of Connecticut (http://engr.uconn.edu/~hanchen)

Nanosynthesis is an enabling element of various energy technologies. While experimentations (to be contrasted with experimental investigations) may lead to the synthesis of beautiful/useful nanostructures, the old fashioned surface science often governs such synthesis processes. Understanding the surface science may not be the absolute necessity for nanosynthesis by chance, but it is necessary for nanosynthesis by design.

This presentation covers three elements of nanosynthesis - kinetics, kinetics-controlled length scale, and predicted self-assembly in nanosynthesis. The first element is the discovery of a kinetic barrier for diffusion of adatoms between nanoscale surface facets. In cooperation with other physical quantities (such as rate of step flow or bunching, temperature, synthesis rate, and other kinetic rates), this kinetic barrier leads to a surface characteristic length scale during synthesis – this discovery is the second element of the presentation. Integration of these two discoveries with existing knowledge - twin formation and geometrical shadowing - leads to a predicted self-assembly during nanorod synthesis. Our studies rely primarily on atomistic simulations (density-functional-theory based ab initio calculations, classical molecular dynamics, and kinetic Monte Carlo simulations) and analytical formulations. We look at experiments for validation and inspiration. The prediction of the self-assembly, based on integration of new discoveries and existing knowledge, has been validated by a subsequent magnetron sputtering deposition experiment.

Bio: Hanchen Huang holds a School of Engineering Named Professorship (Chair Professorship) in Sustainable Energy at the University of Connecticut. His home department is Mechanical Engineering, and he also holds joint appointment in the Materials Science & Engineering Program, the Institute of Materials Science and the Center for Clean Energy Engineering. During transition period of 2009/2010, he is also an adjunct professor at the Rensselaer Polytechnic Institute. In May-June 2010, he is the Royal Society of London KTP Visiting Professor, hosted by Hong Kong PolyU. His research focuses on atomistic simulations of materials and mechanics. Over the past 12 years, he has taught various classes in mechanical, aerospace, nuclear, and materials engineering. Before his teaching career, he worked as a post-doc and then term staff member at Lawrence Livermore National Lab. Hanchen received his PhD in nuclear engineering from UCLA in 1995; his early education (MS/BS) in China was in theoretical physics.