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| Tomas Baer | |
| Kenan Professor of Chemistry | |
baer@unc.edu |
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| Research Interests | |
| Kinetics, Mass Spectrometry, Environmental Chemistry | |
| Professional Background | |
| Ph.D., Cornell University(1969); M.A., Wesleyan University(1964); B.A., Lawrence University(1962); J.S. Guggenheim Fellow 1976-1977; Fellow of the American Physical Society (elected 1985); Lucia R. Briggs Distinguished Achievement Award, Lawrence University, 1993 | |
| Research Synopsis | |
 Our
research interests lie in the areas of kinetics, mass spectrometry,
and environmental chemistry. The common feature (see figure, click
to enlarge) among the various experiments is the creation of ions
by photon-molecule interactions and the analysis of the resulting
ions by time-of-flight (TOF) mass spectrometry. The research is
of interest to physical, analytical, and environmental chemists.
The aerosol experiment involves the generation, reaction and detection
of aerosol particles by single particle laser initiated TOF mass
spectrometry.
Three different projects are pursued. We are developing new methods for aerosol particle analysis, especially the organic constituents that are very difficult to quantify by current methods. One approach is vaporization by either a heater or an IR laser, followed by one-photon ionization using a vacuum UV laser. Gas-surface reactions between reactive pollutants, such as ozone, OH, HNO3, and model aerosol particles are studied in a flow tube located in front of the mass spectrometer. The reaction progress can be followed in real time and reaction products identified. Finally, explosive combustion of aerosol particles consisting of energetic materials such as nitromethane, TNT, peroxides, etc. can be initiated by rapid heating of the particles with the IR laser and the reaction intermediates detected with the vacuum UV laser. We learn about the reaction mechanism in the early stages of the reaction, information that is very difficult to obtain for rapid combustion reactions, which under certain conditions can be explosive. A final project involves photoelectron photoion coincidence (PEPICO) spectroscopy in which we prepare ions with selected internal energies and study their dissociation dynamics, again by TOF mass spectrometry. The analysis of the data require extensive ab initio MO and DFT calculations in order to learn about the energetics, structure, and reaction mechanisms of ions, free radicals, and other transient species. Among the molecules investigated are organometallic complexes, such as CpMn(CO)3, organic molecules such as ethylene glycol and acrolein, and transient species such as the vinyl radical. Some of the work is carried out at the Chemical Dynamics Beamline in Berkeley, where we participate in a variety of photoionization experiments at the Advanced Light Source synchrotron. |
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Last Updated:
January 17, 2007
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