My major area of research interest is analytical spectroscopy, with an emphasis on the development of new analytical techniques and instrumentation for elemental analysis. In recent years a significant portion of my group's effort has been in the study of matrix effects in
inductively coupled plasma mass spectrometry (ICPMS). Changes in instrument response with changes in sample composition present a major challenge to users of ICP-MS. With laser excited atomic and ionic fluorescence, we measure ion densities and velocities at various
locations in the differentially-pumped vacuum interface that separates the ICP from the mass spectrometer. We are using those measurements to develop a better understanding of how ions are transmitted through the interface, and how that transmission is affected by sample matrix. This work is funded by the Department of Energy.

A second set of experiments funded by DOE focuses on new atmospheric-pressure ionization techniques for mass spectrometric analysis, including DESI and DART.  These new ion sources are capable of rapid analysis of a variety of samples with little or no sample
preparation.  However, the mechanisms by which they work have not yet been worked out.  We are studying how these ion sources remove ions from surfaces by watching the ions on a surface with a fluorescence microscope while the ion source is removing and ionizing them.  With these experiments we hope to gain a better fundamental understanding of how the ion sources work.

My group is part a large team that has been developing separation and identification techniques for proteins. Our contribution to the effort
has been in the development of sensitive detectors that use either one or two photons to excite native fluorescence in protein molecules.

Work in my research group is challenging, yet rewarding. My students gain valuable exposure to mainstream analytical techniques, and at the same time gain practical experience with mechanical and electrical design, computer programming, and computer interfacing.