Terrance McMahon

Terrance McMahon
Professor Emeritus, University Professor
Location: C2 272
Phone: 519-888-4591
Status: Emeritus


The McMahon group investigates structures, energetics and reaction dynamics of gaseous ions. The majority of their work uses high pressure mass spectrometry (HPMS) to explore cluster ions. HPMS is uniquely suited for determining the energetics of gaseous ion-molecule equilibria, particularly those associated with ion-molecule clustering and exchange reactions. Using this technique, they have amassed a considerable database for the energetics and kinetics of a wide variety of cluster species.

Over the past decade, they have also used the free electron laser at the Centre Laser Infrarouge d’Orsay (CLIO, Université Paris-Sud XI) to perform infrared multiple photon dissociation (IRMPD) spectroscopy experiments in the mid-infrared ‘fingerprint’ region. This is a form of consequence spectroscopy that allows detailed ion structures to be identified from characteristic absorption frequencies. These experiments are supported by high-performance quantum chemical calculations at Waterloo that help reveal the intrinsic properties of gas-phase ions.

Research Interests

  • Gaseous ion energetics and structure
  • Fourier transform ion cyclotron resonance spectrometry
  • High pressure mass spectrometry
  • Infrared multiple photon dissociation
  • Ion-molecule reaction dynamics
  • Devices and Analytical Methods


  • 1974 Ph.D., Physical Chemistry, California Institute of Technology, USA
  • 1969 B.Sc., Chemistry, University of Alberta, Canada


  • 2005 University Professor, University of Waterloo
  • 2015 F.P. Lossing Award of the Canadian Society for Mass Spectrometry
  • 2015 John C. Polanyi Award – Canadian Society for Chemistry
  • 1993 Barringer Award of the Spectroscopy Society of Canada
  • 1986-1988 E.W.R. Steacie Fellow


  • 2007-2015 Dean of Science
  • 2009 Department of Chemistry Review (University of Western Ontario)

Selected/Recent Publications

  • Featherstone, J., Chong, T., Martens, J. K., Oomens, J., & McMahon, T. B. (2018). Inverse Sandwich Cyclopentadienyl Complexes of Sodium in the Gas Phase. The Journal of Physical Chemistry A, 122(43), 8659-8664.
  • Ieritano, C., Featherstone, J., Carr, P. J., Marta, R. A., Loire, E., McMahon, T. B., & Hopkins, W. S. (2018). The structures and properties of anionic tryptophan complexes. Physical Chemistry Chemical Physics, 20(41), 26532-26541.
  • Fu, W., Carr, P. J., Lecours, M. J., Burt, M., Marta, R. A., Steinmetz, V., ... & Hopkins, W. S. (2017). Intramolecular cation–π interactions in protonated phenylalanine derivatives. Physical Chemistry Chemical Physics, 19(1), 729-734.
  • Simidzija, P., Lecours, M. J., Marta, R. A., Steinmetz, V., McMahon, T. B., Fillion, E., & Hopkins, W. S. (2016). Changes in Tricarbastannatrane Transannular N–Sn Bonding upon Complexation Reveal Lewis Base Donicities. Inorganic chemistry, 55(19), 9579-9585.
  • Ziegler, B. E., Lecours, M., Marta, R. A., Featherstone, J., Fillion, E., Hopkins, W. S., ... & McMahon, T. B. (2016). Janus face aspect of all-cis 1, 2, 3, 4, 5, 6-hexafluorocyclohexane dictates remarkable anion and cation interactions in the gas phase. Journal of the American Chemical Society, 138(24), 7460-7463.
  • Ieritano, C., Carr, P. J., Hasan, M., Burt, M., Marta, R. A., Steinmetz, V., ... & Hopkins, W. S. (2016). The structures and properties of proton-and alkali-bound cysteine dimers. Physical Chemistry Chemical Physics, 18(6), 4704-4710.

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