Neutron Scattering Studies of Hydrogen Bonding

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In this project, funded by the Experimental Physical Chemistry Program of the Chemistry Division, Prof. Bruce S. Hudson of Syracuse University will investigate the nature of hydrogen bonding, with emphasis on short, symmetric hydrogen bonds and the cooperative nature of hydrogen bond formation. The major experimental techniques used are vibrational inelastic neutron scattering (INS) spectroscopy and deep inelastic neutron scattering (DINS), using the ISIS facility in the United Kingdom and that of the NIST Center for Neutron Research. These techniques possess advantages over the commonly used infrared and Raman spectroscopic methods: the spectral intensities are easily and reliably computed from proposed nuclear dynamics, and the higher sensitivity of INS spectroscopy to motions of hydrogen atoms relative to all other atoms, including deuterium. Ab initio and density functional theory (DFT) modeling methods will be used to compute the INS vibrational spectra and the DINS scattering functions. The objective of this study is to establishment the limits of validity of theoretical descriptions of hydrogen bonding in the organic solid state. This is a necessary condition for the rational design of nanostructured materials, nonlinear optical materials and organic electronic devices, for the control of polymorphism in pharmaceuticals and in predicting the structures of globular proteins or designing inhibitors of their function.Graduate and undergraduate students participate in this research, as are postdoctoral research associates. The research will lead to the development of fundamentals of hydrogen bond interaction in self-assembling organic structures, which are the most important structure-specific interactions that are in reversible equilibrium at room temperature under ambient conditions.