Director, Environmental Metrology & Policy Program, 7/2017-present
Chair, Chemistry Department, 7/2010-6/2017
Professor, Chemistry Department, Georgetown University, 8/2010–present
Associate Professor, Chemistry Department, Georgetown University. 8/2006–7/2010
Assistant Professor, Chemistry Department, Georgetown University, 8/2001-7/2006.
Senior Research Associate, 4/1999-7/2001; Research Associate, 11/1996-3/1999, University of Illinois at Urbana-Champaign, with Professors Eric Oldfield and Andrzej Wieckowski.
Visiting Staff Scientist, Institut de Recherches sur la Catalyse, CNRS, Villeurbanne, France, 1/95- 10/96.
Ph.D Student, Swiss Federal Institute of Technology-Lausanne, 1989-1994, with Dr. J. J. van der Klink.
Junior faculty member, NMR Laboratory, Research Center for Analysis & Measurement, Fudan University, Shanghai, 7/1986-6/1989.