%0 Journal Article %J Physical Review Letters %D 2013 %T Fundamental Aspects of Parahydrogen Enhanced Low-Field Nuclear Magnetic Resonance %A Colell, J. %A Turschmann, P. %A Gloggler, S. %A Schleker, P. %A Theis, T. %A Ledbetter, M. %A Budker, D. %A Pines, A. %A Blumich, B. %A Appelt, S. %K exchange %X

We report new phenomena in low-field H-1 nuclear magnetic resonance (NMR) spectroscopy using parahydrogen induced polarization (PHIP), enabling determination of chemical shift differences, delta nu, and the scalar coupling constant J. NMR experiments performed with thermal polarization in millitesla magnetic fields do not allow the determination of scalar coupling constants for homonuclear coupled spins in the inverse weak coupling regime (delta nu < J). We show here that low-field PHIP experiments in the inverse weak coupling regime enable the precise determination of delta nu and J. Furthermore we experimentally prove that observed splittings are related to delta nu in a nonlinear way. Naturally abundant C-13 and Si-29 isotopes lead to heteronuclear J-coupled H-1-multiplet lines with amplitudes significantly enhanced compared to the amplitudes for thermally prepolarized spins. PHIP-enhanced NMR in the millitesla regime allows us to measure characteristic NMR parameters in a single scan using samples containing rare spins in natural abundance. DOI: 10.1103/PhysRevLett.110.137602

%B Physical Review Letters %V 110 %P 137602 %8 Mar 26 %@ 0031-9007 %G English %U ://WOS:000316685100032 %N 13 %M WOS:000316685100032 %! Fundamental Aspects of Parahydrogen Enhanced Low-Field Nuclear Magnetic Resonance %R Doi 10.1103/Physrevlett.110.137602 %0 Journal Article %J Physical Review Letters %D 2011 %T Near-Zero-Field Nuclear Magnetic Resonance %A Ledbetter, M. P. %A Theis, T. %A Blanchard, J. W. %A Ring, H. %A Ganssle, P. %A Appelt, S. %A Blumich, B. %A Pines, A. %A Budker, D. %K mri %X

We 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 ://WOS:000294406600017 %N 10 %M WOS:000294406600017 %! Near-Zero-Field Nuclear Magnetic Resonance %R Doi 10.1103/Physrevlett.107.107601 %0 Journal Article %J Physical Review B %D 1997 %T Enhancement of surface NMR by laser-polarized noble gases %A Room, T. %A Appelt, S. %A Seydoux, R. %A Hahn, E. L. %A Pines, A. %K he-3 %X

The transfer of spin polarization from laser-polarized helium and xenon to spins such as H-1 and C-13 On the surface of high-surface-area solids (Aerosil) is demonstrated over a temperature range from 4 to 200 K. The transfer mechanism is dipole-dipole cross relaxation between the spins of the adsorbed mobile noble gas and the surface spins (spin-polarization-induced nuclear Overhauser effect). The enhancement of surface proton magnetization by laser-polarized helium at 4 K and 10 K is between one and twofold. Using laser-polarized xenon, enhancement factors of up to 20 were obtained when compared to the Boltzmann polarization in a field of 4.2 T and at a temperature of 130 K.

%B Physical Review B %V 55 %P 11604-11610 %8 May 1 %@ 0163-1829 %G English %U ://WOS:A1997WY50400096 %N 17 %M WOS:A1997WY50400096 %! Enhancement of surface NMR by laser-polarized noble gases %R Doi 10.1103/Physrevb.55.11604 %0 Journal Article %J Chemical Physics Letters %D 1997 %T SQUID detected NMR of laser-polarized xenon at 4.2 K and at frequencies down to 200 Hz %A TonThat, D. M. %A Ziegeweid, M. %A Song, Y. Q. %A Munson, E. J. %A Appelt, S. %A Pines, A. %A Clarke, J. %K relaxation %X

A spectrometer based on a dc SQUID (superconducting quantum interference device) was used to record nuclear magnetic resonance signals from laser-polarized Xe-129 at 4.2 K and at frequencies ranging from about 200 Hz to 110 kHz in magnetic fields varying from about 0.02 to 9 mT. The Xe-129 resonance linewidths were found to increase with increasing magnetic field, and, at a given field, to increase with higher Xe-129 concentration. The spin-lattice relaxation times were observed to decrease from similar to 8000 s at 5 mT to similar to 2000 s at fields below 0.05 mT. Such long relaxation times make possible a variety of spin polarization transfer experiments. (C) 1997 Published by Elsevier Science B.V.

%B Chemical Physics Letters %V 272 %P 245-249 %8 Jun 27 %@ 0009-2614 %G English %U ://WOS:A1997XH44000017 %N 3-4 %M WOS:A1997XH44000017 %! SQUID detected NMR of laser-polarized xenon at 4.2 K and at frequencies down to 200 Hz %R Doi 10.1016/S0009-2614(97)88016-5 %0 Journal Article %J Science %D 1996 %T Enhancement of solution NMR and MRI with laser-polarized xenon %A Navon, G. %A Song, Y. Q. %A Room, T. %A Appelt, S. %A Taylor, R. E. %A Pines, A. %K resonance %X

Optical pumping with laser light can be used to polarize the nuclear spins of gaseous xenon-129. When hyperpolarized xenon-129 is dissolved in liquids, a time-dependent departure of the proton spin polarization from its thermal equilibrium is observed, The variation of the magnetization is an unexpected manifestation of the nuclear Overhauser effect, a consequence of cross-relaxation between the spins of solution protons and dissolved xenon-129. Time-resolved magnetic resonance images of both nuclei in solution show that the proton magnetization is selectively perturbed in regions containing spin-polarized xenon-129. This effect could find use in nuclear magnetic resonance spectroscopy of surfaces and proteins and in magnetic resonance imaging.

%B Science %V 271 %P 1848-1851 %8 Mar 29 %@ 0036-8075 %G English %U ://WOS:A1996UC77800041 %N 5257 %M WOS:A1996UC77800041 %! Enhancement of solution NMR and MRI with laser-polarized xenon %R Doi 10.1126/Science.271.5257.1848