Dr. Dennis W. Tokaryk
Optical and Near-Infrared Laser Spectroscopy
Molecules of Astrophysical Interest
A number of simple molecules like H2, CO, CO2, CN, etc. are found frequently in astrophysical environments, such as comets, carbon star atmospheres, planetary nebula, and even the interstellar medium. In my laboratory, we create these kinds of molecules, and study their structure in detail by probing them with lasers. Many of these compounds are unstable (radicals), since they react quickly with other molecules and disappear. We must therefore apply techniques of very high sensitivity to collect their spectra (the set of frequencies at which the molecule will absorb or emit light). We create unstable species with a variety of techniques - electrical discharges, supersonic jet expansions, or with a laser ablation apparatus. Lately we have determined how the carbon cluster C3 vibrates in its lowest excited states, and this has implications for the assignment of a nebular emission to C3. We have also found new spectra of HCN (probably!) and C2H, both prominent in interstellar space. Work in the laboratory teaches you a lot about optics, lasers of various kinds, and quantum mechanics (needed to describe the spectral patterns arising from the molecules.) Since I work closely with Drs. Adam and Linton, students have opportunities to work in a larger group, and to work in other locations, since I also collaborate with groups and UNB Saint John, York University, University of Calgary, and the National Research Centre in Ottawa.
Pollution and Environmental Monitoring with Lasers
I have recently joined the Canadian Institute for Photonic Innovations (CIPI), one element of the Federal Centres of Excellence Program. I am looking at using a technique called ‘cavity ring down laser spectroscopy’ (CRDS) to monitor very minute quantities of toxic gases in the environment. In CRDS, a small amount of laser light is admitted into an optical cavity made from two highly reflective (R~99.99%) mirrors. This light will bounce back and forth up to 10,000 times inside the cavity, allowing for a very long interaction path between the beam and molecules inside! I hope apply this technique to unstable radicals associated with atmospheric pollution.