Assistant Professor of Chemistry
B.S., Gettysburg College;
Ph.D., University of North Carolina, Chapel Hill
Kinetics, thermodynamics, atmospheric chemistry, mass spectrometry
Threshold Photoelectron Photoion Coincidence Time-of-flight mass spectrometry (TPEPICO TOF-MS)
Our group is interested in the unimolecular dissociation dynamics of energy-selected gas phase ions. Reaction dynamics are probed through the technique of threshold photoelectron photoion spectroscopy (TPEPICO) in which ions are prepared with selected internal energies and dissociation products are recorded using a custom built time-of-flight mass spectrometer. Our work is carried out at the college and at the Paul Scherrer Institut in Villigen, Switzerland where we use an imaging PEPICO apparatus coupled to the X0DB40 beamline at the Swiss Light Source. Our recent work has focused on a series of germanium halides, Cr(CO)6, Fe(CO)5, and ethylchloride.
 Nicholas Shuman, James P. Kercher, and Tomas Baer. Modeling The Dissociation Dynamics of Energy-Selected Neopentylamine Ions: Heats of Formation of Neopentylamine and Neopentyl Alcohol Int. J. Mass Spec. 2008, 278, 26-31.
 James P. Kercher, Will Stevens, Zsolt Gengelizcki, and Tomas Baer. Modeling Unimolecular Dissociations from a Temperature Controlled TPEPICO Study on 1-C4H9I+ Ions. Int. J. Mass Spec. 2007, 267(1-3) 159-166.
 James P. Kercher, Zsolt Gengeliczki, Bálint Sztáray, and Tomas Baer. Dissociation Dynamics of Sequential Ionic Reactions: Heats of Formation of Tri-, Di-, and Monoethyl Phosphine Ions. J. Phys. Chem. A, 2007, 111(1), 16-26.
In situ detection of reactive halogen precursors using Chemical Ionization Mass Spectrometry
A second project involves the investigation of the activation of inert halides from the condensed phase to the gas phase through heterogeneous chemistry involving reactive oxides of nitrogen. The trace gases in the air are sampled into a chemical ionization mass spectrometer (CIMS) for identification. This work is carried out at the James H. Barrow Field Station. We regularly contribute to large scale air-quality campaigns, most recently Vernal, UT as part of the UBWOS study.
 Felipe D. Lopez-Hilfiker, Kevin Constantin, James P. Kercher, and Joel Thornton. Temperature-Dependent Halogen Activation by N2O5 reaction on Halide-Doped Ice Surfaces. Atm. Chem. Phys. Dis., 2012,(12), 6085-6112.
 Joel A. Thornton, James P. Kercher, Theran P. Reidel, Nicholas L. Wagner, Julie Cozic, John S. Holloway, Willian P. Dube, Glenn M. Wolfe, Patricia K. Quinn, Ann M. Middlebrook, Becky Alexander, Steven S. Brown. A large atomic chlorine source inferred from mid-continental reactive nitrogen chemistry. Nature, 2010, 464, 271.
 James P. Kercher, Theran P. Reidel, and Joel A. Thornton. Chlorine Activation by N2O5: Simultaneous, In Situ Detection of ClNO2 and N2O5 by Chemical Ionizaiton Mass Spectrometry.Atmos. Meas.Tech.,2009, 2, 1-12.