Greg Gillen is currently a Research Chemist in the Surface and Microanalysis Science Division at the National Institute of Standards and Technology (NIST). He graduated from the University of California Santa Barbara in 1983 with a bachelor's degree in chemistry. He received a PhD in Analytical Chemistry from Arizona State University in 1987 with an emphasis on Secondary Ion Mass Spectrometry (SIMS). He joined NIST as a Postdoctoral Research Associate in 1988 and became a staff scientist in 1989 and served as group leader of the NIST Surface and Trace Chemical Analysis Group from 2001-2018. His research interests include: surface analysis, microscopy, ion solid interactions, biological and organic mass spectrometry, ion mobility spectrometry, secondary ion mass spectrometry, cluster bombardment of surfaces, materials deposition inkjet printing, raman and optical spectroscopy and trace explosives detection. He has served as a technical organizer of two yearly scientific conferences including the "Annual Workshops on Secondary Ion Mass Spectrometry and Trace Explosives Detection". He has served as an organizer and program chair of the International Conference on Secondary Ion Mass Spectrometry (SIMS) and is currently serving on the International SIMS International Conference Organizing Committee. He was co-editor of "SIMS XI", a 1100 page, hard cover proceedings book of the 11th International Conference on SIMS published in 1998. He was the recipient of a Department of Commerce Bronze Medal for research on "Molecular Compositional Mapping by SIMS" and two Department of Commerce Silver Medals for research related to the "Development of Polyatomic Primary Ion Sources for Surface Analysis" and "Development of Measurements and Standards Infrastructure for Trace Explosives Detection". He is a former co-director of the Chemistry undergraduate research fellowship program at NIST. He is a member and former chairman of the ASTM E42.06 subcommittee on Secondary Ion Mass Spectrometry and has served on the board for the Applied Surface Science Division of the American Vacuum Society. He has published ~ 175 scientific papers and conference proceedings on various aspects of surface analysis and has given numerous presentations at national and international conferences. His most recent research has focused on development of a standards and metrology program for trace detection of explosives and narcotics.