Telephone: 519-824-4120 x53982
Office: MacN 223
Online: Guelph XAFS group
I obtained my B.Sc. in Theoretical Physics in 1982 from Jilin University, P.R. China. In 1984 on a scholarship from the Education Ministry of PRC I joined the M.Sc. graduate study program in the Physics Department of Simon Fraser University, then in 1986 I transferred into the Ph.D. program in the same department and in 1991 I obtained my doctoral degree in Condensed Matter Physics. From 1991-1994 I had my postdoctoral training in the Chemistry Department at the University of Western Ontario, during the time period 1992-1994 I was supported by a NSERC postdoctoral fellowship.
From 1982-1984 I worked as an Assistant Lecturer in the Physics Department, Jilin University. From 1994-1999 I was involved in the construction of the Sector 20 synchrotron radiation beamline facility at the Advanced Photon Source (APS), Argonne National Laboratory, initially as an research associated working offsite at Simon Fraser University (1994-1996) and then as the beamline scientist for 20ID/APS (1996-1999). From 2000-2005 I worked as a staff scientist at the then newly established Canadian Light Source (CLS), and since year 2001 I have been appointed as an Adjunct Professor in the department of Physics and Engineering Physics, University of Saskatchewan. In 2005 I joined the Department of Physics at the University of Guelph, as an Assistant Professor.
Since the beginning of the CLS Hard X-ray Micro-Analysis beamline project in 2000, I have been serving as the Beam Team Leader coordinating its design, construction and user operation. During 2000-2003 I served as a member of the CLS Users’ Advisory Committee; and have been a member on the CLS Beamline Advisory Committee since 2000. I have been serving as referee for a number of international journals and for NSERC; as external examiner for PhD theses for McGill and Waterloo. In the ongoing CLS Brockhouse Sector development project I am a Co-PI and function as a consultant for technical issues. I am also an co-applicant for the PNCSRF operation supported by an NSERC MFA which operates the Canadian portion of the Sector 20 at the APS, Argonne National Laboratory.
KEYWORDS: Condensed matter physics, Interface structure and function of electronic thin films of organic semiconductor and metal silicides, grazing-incidence X-ray scattering and spectroscopy techniques, arsenic speciation in environmental systems
My current research involves four aspects: 1. growth and structural property studies of organic semiconductor films; 2. structural properties of nickel silicide thin films; 3. arsenic speciation in environmentally important systems; 4. structural properties of materials under extreme conditions. The common theme is applying a multitude of synchrotron radiation based techniques to probe the atomic/molecular structures for understanding the structure-function relationships and in some cases for acquiring the atomic/molecular level control of complex structures.
In the first area, our effort has been focused on the polyacene semiconductor thin films. Three projects are underway: A. in situ and exsitu carbon 1s polarization dependent NEXAFS studies on the tetracene and pentacene growth mechanisms on various solid substrates; B. gas phase NEXAFS of the polyaromatic molecules and theoretical simulation (StoBe code); C. exsitu grazing-incidence X-ray diffraction (GIXD) study on the thickness dependence of the expitaxial structures of tetracene on reduced silicon surfaces. The polyacene thin film NEXAFS and GIXD projects are in collaboration with Qin (U of G) group. Systems studied include tetracene and pentacene on H/Si(001) (wet chemistry method) and SiO2 substrates; and tetracene on flat and specific terraced H/Si(001) substrates. The polyacene gas phase project aims at developing a thorough understanding of the C 1s near edge X-ray absorption spectroscopy of these molecules for application as a structural tool in studying the polyacene semiconductor films. In the second area, we’ve been collaborating with Lavoie’s group (IBM, Yorktown Heights) to investigate the XANES and XAFS signatures of the industrial nickel silicide layers targeted for new generations of nanoscale electronic applications. Recently we have demonstrated that the method we’re developing is capable to identify the epitaxial phase of an interface region with thickness of 1-3 nm, where conventional diffraction methods have not been effective. The third research area, the Arsenic speciation using XAFS endstation at CLS HXMA beamline has been carried out in collaboration with N. Chen (CLS), G. Demopoulos (McGill), and J. Rowson (AREVA Res., Canada), and S. Glasauer (Dept. of Land Resource Sci., U of Guelph). In these studies we have systematically studied the pH, temperature, and aging time factors in the formation of scorodite phase under the geochemical conditions mimicking that at uranium mine tailing process facilities. For the fourth area, the study of materials under extreme conditions involves diffraction and XAFS studies under high pressure environment generated with diamond anvil cells (DAC) (J. Tse/U of S, S. Desgreniers/U Ottawa, D. Klug/NRC, N. Chen and C.Y. Kim/CLS), aimed at the fundamental structural and electronic properties of materials under high pressure. A new research project is in progress which will invoke x-ray absorption spectroscopy studies on material electronic structures under high pressure.