Ultrafast Molecular Sciences

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Molecular sciences in the 20th century was based on understanding the structure of the microscopic world. It is hard to overstate how important this was. Discerning the shapes of molecules and solids led to structure-function relationships which engendered Molecular Biology, computer chips, plastics and drug design. Nature, however, is not static: there are many rapid molecular processes underlying photosynthesis, vision, solar energy conversion etc. In the 21st century, we must go beyond ‘structure’ and develop a dynamical understanding of nature’s processes. This proposal is directed towards this goal. Specifically, using novel ultrafast electron and X-ray techniques, we will study fundamental aspects of molecular dynamics, with a view towards developing simple ‘rules’ which govern how, on ultrafast (femtosecond) time scales, electronic charge and energy flow during such processes. Ultrafast Molecular Sciences is based on revolutionary advances in high power laser technology, now permitting ultrashort pulse generation from the infrared to the soft X-ray regions. This proposal builds on CFI-supported major infrastructure, with NSERC-supported HQPs carrying out the research program. High power ultrashort pulse laser technology offers many new opportunities beyond generating IR or X-ray pulses. The electric forces associated with such light pulses can be even stronger than the electric forces which bind matter itself. This means that researchers can align or shape molecules using laser fields. Here, we will use our ability align molecules. Molecules are generally randomly oriented and therefore our studies of their dynamics are somewhat blurred. Much like forcing children to line up for a group photograph, we can use laser electric forces to line molecules up so that we may observe their dynamical processes much more clearly. We will develop techniques for aligning molecules in 3D, allowing us to apply our novel electron and X-ray spectroscopies to them with maximal benefit. As ultrashort laser fields get even stronger, new physical processes occur. One process, called strong field ionization, has led to a new branch of physics called Attosecond Science, itself a Canadian invention. This field has produced the world’s shortest light pulses and now permits researchers to study the fastest processes within molecules - namely, how electrons move within molecules and materials. However, the models and techniques developed thus far only apply to very simple systems such as atoms. In order to broaden the scope, we will study how these attosecond methods apply to more complex molecules, a requirement for advancement. Finally, we use ultrashort pulses to develop new forms of microscopy which permit chemical-specific imaging of samples without adding any dyes or stains. This new type of imaging is important for fields ranging from biomedicine, to material science, to natural resources.