NMR Studies of Molecular Motion in Constrained Environments

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In this project in the Physical Chemistry Program of the Chemistry Division, Prof. Gina Hoatson of the College of William and Mary will engage in developing new techniques of pulsed nuclear magnetic resonance (NMR) spectroscopy in order to expand the accessible range of time scales over which the rates of molecular motion as well as the associated dynamical trajectories can be determined. These include methods of selective inversion, the determination of double quantum line shapes, methods of Hadamard excitation spectroscopy, which is a variant of stochastic NMR possessing considerable advantages over conventional pulsed NMR, and spectral density measurements on powders. Systems to be investigated in the course of this work include molecular crystals, inclusion compounds, and liquid crystals. %%% Nuclear Magnetic Resonance (NMR) spectroscopy is a powerful, ubiquitious method for the study of solids and liquids through the interaction of nuclear magnets of the constituent atoms with electromagnetic radiation. The absorption of this radiation by the nuclear magnets is not only characteristic of the specific chemical element but is also affected by the chemical environment. The atomic nuclei thus act as microscopic probes and yield site specific information about the structure and dynamics of the solid or liquid substance. Continual developments in theoretical and experimental techniques have resulted in vastly improved performance of the NMR method as a tool for basic studies of the properties of condensed matter and have greatly expanded its application to problems in physics, chemistry, materials science, biology, and medicine. In this project further developments are planned to enable the NMR method to deal with difficult or so far undoable problems and thereby extend the range of its applicability to practical problems.