Molecular Relaxation by ESR Spectroscopy and Related Phenomena

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Dr. Jack H. Freed of Cornell University is funded for his research on molecular relaxation by ESR spectroscopy and related phenomena by the Physical Chemistry Program of the Chemistry Division. Studies of dynamic molecular processes and structure in complex fluids will be continued. New two-dimensional Fourier transform (2D-FT) ESR, including electron-electron double resonance (2D-ELDOR), and far infrared (FIR) ESR techniques and accompanying theoretical developments will be employed to study rotational molecular dynamics in liquids over the 9 to 250 GHz regime. In particular, the dynamic cage model will be tested, especially in the context of glass-forming liquids. These methods also will be applied to the study of the quantum rotational nature of spin relaxation in argon matrix trapped methyl radicals below 40K. Comparisons of microscopic and macroscopic translational diffusion in liquids will be made using dynamic-imaging of diffusion (DID)-ESR for the measurement of macroscopic diffusion and 2D-ELDOR for microscopic diffusion. The new double-quantum coherence (DQC)-ESR method will be developed for the measurement of distances in organic biradicals, and for distance distributions in bilabeled polymers. The detection and analysis of structure in fluids remains a challenging and important area of physical chemistry and is key to many important chemical processes. Dr. Freed's laboratory at Cornell Unviersity will continue extending the utility of ESR spectroscopy to the analysis of diffusion processes in complex liquids (such as polymeric solutions). The advances provided by these studies provide technical leadership in the discipline, and impact many other laboratories. The results to be provided will extend our understanding of liquid structure and of solution structure.