Vibrational spectroscopy microscopy and computational modelling

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In our research, we probe the composition of matter with visible and infrared light, using a technique called vibrational spectroscopy. This technique works on the principle that molecules are a lot like tuning forks. When struck against something solid, like a table, the fork vibrates. Molecules are a lot smaller; and instead of a table, we hit them with light. If the wavelength is just right, a molecule can absorb the energy and begin to vibrate: bonds stretch, twist, rock, etc. Each molecule absorbs a unique set of light energies, which vary with the number and type of atoms in a molecule, and with the ways in which the atoms are connected to each other. We work backward from the set (or vibrational spectrum) of wavelengths absorbed to get information about molecular structure. Another thing that we can investigate is the amount of light that is absorbed: some vibrations are easier to get started than others. The differences are known to depend on a molecule's structure; now we are trying to pinpoint the specific factors that make some vibrations different from others. State of the art computer modeling is combined with measurement of vibrational spectra. So far, we have concentrated our studies on hydrocarbon molecules, the sorts of things found in oil and gasoline, since these provide us with a vast variety of molecules, all constructed from the same two building blocks: carbon and hydrogen. These molecules are of great importance in fields such as biology, petrochemicals and the plastics industry. The knowledge that we gain has many potential applications, from a better understanding of molecular structure and interactions between molecules, to quantification of trace atmospheric gases and biomedical studies. In this last area of research, biophysical spectroscopy, we record and analyze the vibrational spectra of proteins, such as collagen found in scar tissue, bone and teeth. We also are using the technique to monitor penetration of sunscreen and insect repellent through skin. Finally, we are looking at the spectra of growing fungi, to learn more about these commercially and environmentally important species, at the molecular level.