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In november 1995 professor Futrell recieved the Delaware ACS Section Award for "Distinguished research achievement in an area of chemistry by a member of the Delaware Section of American Chemical Society". A public lecture is required of the award recipient which describes to a lay scientific audience the research for which he(she) is being honored. The lecture developed for this purpose is the current colloquim talk of the author. Abstract of the talk, which has also been presented at the University of Geogia, Emory University, Creighton College, the University of Nebraska and the University of Delaware, is given below.
ABSTRACT: A central theme of the futrell research group for the past decade has been the application of reaction dynamics methods particularly the use of crossed molecular beams to investigate the detailed mechanism of ion activation in tandem mass spectrometry. This technique is very important in analytical applications of mass spectrometry, and is increasingly important as new soft ionization methods are rapidly adapted to the analysis of complex molecular and quasi-molecular ions. An important question addressed in these studies is wheather the fundamental mechanisms of collision activation change dramatically as ion collision energy is varied from the low energy regime typical in ion traps and triple quadrupole instruments to high energy in four-sector, tandem mass spectrometers. Unique research instruments have been constructed at the University of Delaware to address these questions.
This research has radically altered our understanding of energy deposition in tandem mass spectrometry. The widely held general concept that high energy collisions largely involve electronic excitation and low energy collisions only involve vibrational excitation has been demonstrated to be completely incorrect. In special circumstances, the conversion of translational energy into internal energy to fragment molecular ions is more facile by five orders of magnitude than is predicted by general theories for energy transfer. Further, it appears that MS/MS mechanisms are generally impulsive and that angular scattering is a common characterstic in tandem mass spectrometry. This is a major reason that experimental strategies--choice of collision gas and collision energy, for example--are quite different for solving the same structural problem using different kinds of mass spectrometers.
As suggested by the sub-title, deducing this level of detail requires not only unique experimental apparatus but also the analysis of experiments as a scattering event in which we examine trajectories of ions and apply the laws of conservation of angular momentum. This is easily conceptualized as a game of billiards with molecular ions and atoms as the "balls" in play. A very recent discovery in our laboratory is that in certain triatomic cations molecular fragments refuse to play--that is, they are "spectators" in the event, completely uninvolved in momentum exchange in the collision. This has remarkable consequences regarding quantum transitions in early stages of the collision process. It may also have interesting consequences for tandem mass spectrometry studies of complex biomolecules.
Dr. Futrell's research group consists of
To contact Dr. Futrell click here.
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