Research Fellows Directory
Professor Kenneth McKendrick
The work in my group concerns collisions between molecules. Collisions abound in any environment where sufficient molecules are present, including almost all chemical processes of practical interest. They may result in a chemical reaction, with making and breaking of chemical bonds. Alternatively, they may transfer energy between the molecules. We aim to understand exactly what happened during the collision by examining the detailed motions of the products immediately afterwards. By extrapolating backwards, we can infer the impulses that each atom must have felt. We detect the motions through various forms of spectroscopy using different types of lasers.
In particular, we are focussing on a number of relatively unexplored areas where molecular collisions are important. The first is interaction of gas molecules with the surface of a liquid. Much less is currently known about reactions that take place at this boundary than within the bulk of either a gas or a liquid. Even reactions at the related gas-solid interface are better understood, primarily because of a solid surface’s rigidity and regularity. At an atomic scale the boundary between a liquid and a gas is often much less "sharp". Molecules attacking from the gas may be able to penetrate to different depths, affecting whether they or their reaction products are able to re-escape cleanly. Nevertheless, despite this current lack of understanding, this whole area is of profound practical importance. Its relevance spans engineering applications, such as oxidation of lubricants in car engines, through to the biological uptake of oxygen in human lungs.
The second area is the factors that control the flow of energy between molecules when they collide in the gas phase. This is crucial to understanding many important, real-world processes, such as combustion (e.g. the burning of methane for heating or cooking, or of petrol in a car engine). We are studying small free radicals, such as OH, NO and CN, that are key