@article {381,
	title = {NMR with a continuously circulating flow of laser-polarized Xe-129},
	journal = {Journal of Physical Chemistry B},
	volume = {103},
	year = {1999},
	note = {J Phys Chem B203HNTimes Cited:45Cited References Count:35},
	month = {Jun 3},
	pages = {4629-4637},
	abstract = {<p>In this paper we describe the construction of an apparatus for optical pumping of Xe-129 in a circulating gas system connected to a probe for static high-field NMR. The optimal working conditions for the optical pumping under flow are explored, yielding a continuous gas now with a steady-state spin-polarization of about 2\%. It is shown that on various types of high surface area materials a steady-state of adsorbed laser-polarized xenon can be;reached with polarizations of about 0.3\%. NMR spectroscopy of this layer is greatly facilitated due to the renewable magnetization under the continuous-flow conditions allowing unprecedented fast detection of two-dimensional NMR experiments with laser-polarized Xe. The steady-state spin-polarization of adsorbed Xe-129 gives rise to cross-relaxation to surface nuclei such as H-1 and Si-29. A direct spin-polarization-induced nuclear Overhauser effect (SPINOE) to heteronuclei is observed with an enhancement factor of about 20-30. A method is presented for simple modulation of the spin-polarization direction in the fringe field of the high-field magnet; this is exploited to obtain difference SPINOE spectra to highlight only the surface nuclei. Furthermore, a transfer via cross-polarization (CP) from adsorbed Xe to surface protons is demonstrated to select surface groups with reduced mobility compared to SPINOE detection.</p>
},
	keywords = {zeolites},
	isbn = {1089-5647},
	doi = {Doi 10.1021/Jp9821984},
	url = {<Go to ISI>://WOS:000080702600011},
	author = {Seydoux, R. and Pines, A. and Haake, M. and Reimer, J. A.}
}
@article {492,
	title = {Isotropic Chemical-Shifts and Quadrupolar Parameters for O-17 Using Dynamic-Angle Spinning Nmr},
	journal = {Journal of Physical Chemistry},
	volume = {96},
	year = {1992},
	note = {J Phys Chem-UsJk807Times Cited:66Cited References Count:48},
	month = {Aug 20},
	pages = {7001-7004},
	abstract = {<p>Several oxygen-17-enriched silicates were studied using dynamic-angle spinning (DAS) NMR spectroscopy at two magnetic field strengths. The DAS method averages second-order quadrupolar interactions by reorienting a sample about a time-dependent axis, thereby yielding high-resolution spectra for half-odd integer spin quadrupolar nuclei such as oxygen-17. A narrow spectral line is observed for each distinct oxygen site in a powdered sample at the sum of the isotropic chemical shift and the field-dependent isotropic second-order quadrupolar shift. Using equations for the total shift observed at two field strengths, the chemical shift is uniquely determined together with a product of the quadrupolar coupling constant (C(Q) = e2qQ/h) and the quadrupolar asymmetry parameter (eta). For one silicate, we demonstrate aa computer program that uses the isotropic shifts and quadrupolar products as constraints and provides simulations of overlapped magic-angle spinning line shapes. In this way the quadrupolar parameters, C(Q) and eta, are determined separately for each crystallographic site. The silicates studied include the discrete orthosilicates larnite (Ca2SiO4) and forsterite (Mg2SiO4), as well as diopside (CaMgSi2O6), wollastonite (CaSiO3), and clinoenstatite (MgSiO3), which are minerals composed of chains of silicon-oxygen tetrahedra.</p>
},
	keywords = {zeolites},
	isbn = {0022-3654},
	doi = {Doi 10.1021/J100196a028},
	url = {<Go to ISI>://WOS:A1992JK80700028},
	author = {Mueller, K. T. and Baltisberger, J. H. and Wooten, E. W. and Pines, A.}
}
