High-resolution vibrational spectroscopy is a theme that runs throughout our work. To achieve high spectral resolution, continuous wave infrared lasers are used in combination with a free jet vacuum apparatus that cools the sample molecules to a few degrees Kelvin. Cavity ringdown spectroscopy allows us to achieve very high sensitivity. Through collaborations with other institutions, we also use coherence-detected infrared-microwave double resonance spectroscopy (University of Virginia), infrared laser-assisted photofragment spectroscopy (Swiss Federal Institute, Lausanne), and slit-jet Fourier transform infrared spectroscopy (Pacific Northwest National Lab). These techniques are particularly effective in uncovering the couplings among the various molecular vibrations and with rotational motion.
Our work in this area has focused on the infrared spectroscopy of halocarbon compounds. Some halocarbons (CFCs) that are implicated in depletion of the stratospheric ozone layer have been banned. The replacement compounds (HFCs and HCFCs) that are now used in refrigeration and air conditioning still absorb in the infrared atmospheric window and, therefore, contribute to global warming. We are also interested in the spectroscopy of fuels used in combustion and of chemicals produced by combustion in the course of producing energy.
When a molecule is excited with a substantial amount of vibrational energy, the energy does not stay in the prepared vibration but redistributes to other degrees of freedom within the molecule. This phenomenon, termed IVR, is an essential ingredient in understanding the chemical reactivity of excited molecules. When IVR occurs, spectral splittings are observed, such as those illustrated below for nitromethane. We have found that IVR is faster in flexible molecules; therefore, we are studying molecules with large amplitude motions such as internal rotation.
Theoretical work in our group is undertaken in support of the experimental effort in the above areas. This work includes quantum mechanical models of IVR and ab initio molecular structure calculations.
B.S., 1971, University of Toronto
Ph.D., 1975, University of Toronto
Secondary School Teacher, 1975-1977, Minaki, Tanzania
NRCC Postdoctoral fellow, 1977-1979, Stanford University
Assistant Professor, 1980-1986, University of Rochester
Office: KNCL 302B
Lab: KNCL 302