Spectroscopy with Many Significant Figures:

Making High Accuracy Measurements of Gaseous Absorption

---

Absorption and emission of infrared radiation plays a vital role in the dynamics of the atmosphere. Central to the problem of emission or absorption is the frequency dependence or line shape of the absorption coefficient. This is determined by molecular collisions and as such depends upon the composition, pressure and temperature of both the absorber and any host gas.

We have developed a high resolution laser based, difference frequency spectrometer for laboratory based studies of absorption profiles relevant to the atmosphere. Studies of line shapes in our laboratory, both theoretical and experimental, have led to a deeper understanding of the underlying physics of molecular collisions and their impact on absorption spectra. The results can then be included in atmospheric codes. The level of accuracy we have now reached is about 1MHz in 60THz (something around 8-9 significant figures) in frequency and 0.05% in absorption accuracy. With this sort of experimental accuracy available, we now regard a 1% difference between theory and the data as rather poor!

The successful student will need to be willing to work in a laboratory environment with our research group. He or she will learn some laser physics, some atmospheric physics, some computing and a lot of real-life experience working in a research laboratory.

Funding for this project is provided by the Natural Sciences and Engineering Research Council. In addition, Prof. Drummond holds an Industrial Research Chair with COMDEV and ABB BOMEM as the industrial sponsors, with additional support from the Canadian Space Agency, the Meteorological Service of Canada and the Natural Sciences and Engineering Research Council.

For more information, please contact Prof. James R. Drummond