Exploring Dynamics at Surfaces by STM and DFT

Physical and Analytical Chemistry Seminar

Lecturer: Dr. Kai Huang

05-05 Mar 2017 @ 12:30

Location: Faculty Seminar Room

The field of surface chemistry is about the detailed understanding and the control of the behaviors of atoms and molecules at surfaces. The past half century has witnessed the success of surface chemistry in studying single-crystal based “model systems”, and its wide range of high-impact applications in heterogeneous catalysis, semiconductor-based electronics, biomedical devices, photovoltaics, and petrochemical industry. Amongst a large collection of tools to study surface chemistry, “scanning probe microscopies and spectroscopies and density functional theory (DFT)” were highlighted in the 2007 report from the US Department of Energy Basic Energy Sciences Workshop as “have provided us with previously undreamt-of abilities to image surfaces and surface reactions, and to integrate theory with experiment in unraveling reaction mechanisms.”

In this talk, I shall present three examples concerning dynamics at the surfaces of copper, silicon and calcium oxide by STM and DFT. In the first example, I shall present, on a copper surface, selected (mode and bond) reaction dynamics caused by electrons. The second example is concerning patterning a silicon surface by firstly molecular self-assembly, followed by thermal reaction. Two physisorbed states, termed as horizontal (h) and vertical (v), were identified of differing adsorption site, alignment, intermolecular interaction and thermal reactivity. In the last example, I shall describe how the gas-phase oxygen affects the growth morphology of gold particles on a doped CaO film, forming a two-dimensional gold island at zero partial pressure of oxygen versus a three-dimensional gold deposit in 10-6 mbar oxygen.

In addition, I shall briefly describe the proposed research topics that I am hoping to pursue in the near future, by STM and DFT: (a) radiochemistry of iodine-125 film at the nanoscale; (b) chemical characteristics of metal-supported oxide films; (c) theoretical modeling and predicting of surface chemistry of film-materials.