Grant: Discovery Grants Program - Individual

The forces between molecules and between the individual atoms within a molecule are responsible for most physical and chemical properties of gases, liquids and solids, and they govern the exchange of energy by molecular collisions in the atmosphere and other environments. The best experimental probe of such interactions is the discrete high resolution spectroscopy of pairs of interacting atoms and molecules. In particular, experimental observations of the particular patterns of ""colours"" (or wavelengths) of light absorbed or emitted by a particular molecular species can in principle be inverted to yield a detailed knowledge of these forces. A central theme of the proposed work is the development and application of theoretical and computational methods for extracting such information from experimental data, and for predicting other molecular phenomena using the resulting knowledge of intermolecular potential energy functions. ONE PART of the work focuses on very precise studies of two- and three-atom molecules which are small enough that it is possible to perform unified analyses of multiple types of data for different isotopic forms of the same chemical system. Such unified analyses allow us to extract from experiment both accurate knowledge of the intermolecular forces, and subtle information about the coupling between different electronic states and the dependence of the the electronic wavefunctions on internuclear separation. This in turn allow us to make reliable predictions of unobserved portions of the spectra and other properties of such systems. ANOTHER project is concerned with developing and applying methods of simulating the spectroscopic signature of a probe ""chromophore"" molecule solvated in a molecular cluster or trapped in or on a solid matrix. The ability to make accurate predictions of this type will allow us to use such spectroscopic measurements to probe the nature of the microscopic environment where the chromophore molecule is located.