%0 Journal Article %J Physical Review Letters %D 2014 %T Long-lived Heteronuclear Spin-Singlet States in Liquids at a Zero Magnetic Field %A Emondts, M. %A Ledbetter, M. P. %A Pustelny, S. %A Theis, T. %A Patton, B. %A Blanchard, J. W. %A Butler, M. C. %A Budker, D. %A Pines, A. %B Physical Review Letters %V 112 %P 077601 %G eng %N 7 %& 077601 %0 Journal Article %J Journal of the American Chemical Society %D 2013 %T High-Resolution Zero-Field NMR J-Spectroscopy of Aromatic Compounds %A Blanchard, J. W. %A Ledbetter, M. P. %A Theis, T. %A Butler, M. C. %A Budker, D. %A Pines, A. %K density %X
We report the acquisition and interpretation of nuclear magnetic resonance (NMR) J-spectra at zero magnetic field for a series of benzene derivatives, demonstrating the analytical capabilities of zero-field NMR The zeroth-order spectral patterns do not overlap, which allows for straightforward determination of the spin interactions of substituent functional groups. Higher-order effects cause additional line splittings, revealing additional molecular information. We demonstrate resonance linewidths as narrow as 11 mHz, permitting resolution of minute frequency differences and precise determination of long-range J-couplings. The measurement of J-couplings with the high precision offered by zero-field NMR may allow further refinements in the determination of molecular structure and conformation.
%B Journal of the American Chemical Society %V 135 %P 3607-3612 %8 02/2013 %@ 0002-7863 %G English %UWe discuss nuclear spin comagnetometers based on ultralow-field nuclear magnetic resonance in mixtures of miscible solvents, each rich in a different nuclear spin. In one version thereof, Larmor precession of protons and F-19 nuclei in a mixture of thermally polarized pentane and hexafluorobenzene is monitored via a sensitive alkali-vapor magnetometer. We realize transverse relaxation times in excess of 20 s and suppression of magnetic field fluctuations by a factor of 3400. We estimate it should be possible to achieve single-shot sensitivity of about 5 x 10(-9) Hz, or about 5 x 10(-11) Hz in approximate to 1 day of integration. In a second version, spin precession of protons and Xe-129 nuclei in a mixture of pentane and hyperpolarized liquid xenon is monitored using superconducting quantum interference devices. Application to spin-gravity experiments, electric dipole moment experiments, and sensitive gyroscopes is discussed.
%B Physical Review Letters %V 108 %8 Jun 15 %@ 0031-9007 %G English %UWe have recently demonstrated that sensitive and chemically specific NMR spectra can be recorded in the absence of a magnetic field using hydrogenative parahydrogen induced polarization (PHIP)(1-3) and detection with an optical atomic magnetometer. Here, we show that non-hydrogenative para-hydrogen-induced polarization(4-6) (NH-PHIP) can also dramatically enhance the sensitivity of zero-field NMR. We demonstrate the detection of pyridine, at concentrations as low as 6 mM in a sample volume of 250 mu L, with sufficient sensitivity to resolve all identifying spectral features, as supported by numerical simulations. Because the NH-PHIP mechanism is nonreactive, operates in situ, and eliminates the need for a prepolarizing magnet, its combination with optical atomic magnetometry will greatly broaden the analytical capabilities of zero-field and low-field NMR.
%B Journal of the American Chemical Society %V 134 %P 3987-3990 %8 02/2012 %@ 0002-7863 %G English %UWe investigate nuclear magnetic resonance (NMR) in near zero field, where the Zeeman interaction can be treated as a perturbation to the electron mediated scalar interaction (J coupling). This is in stark contrast to the high-field case, where heteronuclear J couplings are normally treated as a small perturbation. We show that the presence of very small magnetic fields results in splitting of the zero-field NMR lines, imparting considerable additional information to the pure zero-field spectra. Experimental results are in good agreement with first-order perturbation theory and with full numerical simulation when perturbation theory breaks down. We present simple rules for understanding the splitting patterns in near-zero-field NMR, which can be applied to molecules with nontrivial spectra.
%B Physical Review Letters %V 107 %8 Sep 1 %@ 0031-9007 %G English %U