Optical Detection of NMR in Liquids

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In this award funded by the Experimental Physical Chemistry Program, Professor Romalis of Princeton University will develop a new detection method for nuclear magnetic resonance (NMR) spectroscopy. NMR is a versatile technique used in clinical medicine, medical research, basic biology, chemistry, and many other fields. It is widely used for studying proteins and other biologically-important molecules, and for non-invasive Magnetic Resonance Imaging (MRI) for medical diagnostics. The vast majority of these applications rely on inductive detection of long-range dipolar magnetic fields created by spin-polarized liquids and solids, the technique prevalent since the inception of NMR. In this project, Professor Romalis will develop a new method for NMR detection using optical rotation of a laser beam passing through the sample. This new method of nuclear spin optical rotation (NSOR) opens a number of new possibilities for NMR spectroscopy and imaging.Professor Romalis and his students will develop a measurement apparatus that allows detection of NSOR signals in a standard 5-mm NMR probe using an optical cavity to increase the signal-to-noise by a factor of 2000. Four directions for initial exploration of the optical detection method are envisioned:First, measurements on common fluids will allow basic understanding of the range of NSOR signals and comparison with previous theoretical calculations of this effect. Second, measurements on molecules with strong isolated absorption peaks in the visible spectrum would allow studies of hyperfine interactions near optical centers. Third, measurements on compounds with heavy elements would identify particularly strong NSOR signals that could be used as markers for direct optical imaging of NMR. Fourth, measurements on molecules with several groups of non-equivalent nuclei will explore the specificity of the NSOR signals and their relationship to chemical shifts.The technical designs will be shared with the community and efforts will be made to commercialize the technology. The project will provide cross-disciplinary training opportunities for students and postdoctoral researchers.