%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 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