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Titolo: Doublequantum doublequantum MAS exchange NMR spectroscopy: Dipolarcoupled spin pairs as probes for slow molecular dynamics
Autore: Schnell, I; Watts, A; Spiess, HW;
 Indirizzi:
 Max Planck Inst Polymerforsch, D55021 Mainz, Germany Max Planck Inst Polymerforsch Mainz Germany D55021 55021 Mainz, Germany Univ Oxford, Dept Biochem, Oxford OX1 3QU, England Univ Oxford Oxford England OX1 3QU Dept Biochem, Oxford OX1 3QU, England
 Titolo Testata:
 JOURNAL OF MAGNETIC RESONANCE
fascicolo: 1,
volume: 149,
anno: 2001,
pagine: 90  102
 SICI:
 10907807(200103)149:1<90:DDMENS>2.0.ZU;2A
 Fonte:
 ISI
 Lingua:
 ENG
 Soggetto:
 SOLIDSTATE NMR; NUCLEARMAGNETICRESONANCE; SIDEBAND PATTERNS; PIPI PACKING; ROTATING SOLIDS; TORSIONAL ANGLE; C13 NMR; HOMONUCLEAR; HEXABENZOCORONENE; POLYETHYLENE;
 Keywords:
 dipolarcoupled spin pairs; doublequantum MAS spectroscopy; exchange spectroscopy; slow molecular dynamics; molecular jump angles and rates;
 Tipo documento:
 Article
 Natura:
 Periodico
 Settore Disciplinare:
 Life Sciences
 Physical, Chemical & Earth Sciences
 Citazioni:
 37
 Recensione:
 Indirizzi per estratti:
 Indirizzo: Spiess, HW Max Planck Inst Polymerforsch, Postfach 3148, D55021 Mainz, Germany Max Planck Inst Polymerforsch Postfach 3148 Mainz Germany D55021



 Citazione:
 I. Schnell et al., "Doublequantum doublequantum MAS exchange NMR spectroscopy: Dipolarcoupled spin pairs as probes for slow molecular dynamics", J MAGN RES, 149(1), 2001, pp. 90102
Abstract
By combining two dipolar doublequantum (DQ) MAS experiments, a homonuclear DODO MAS exchange experiment has been designed, which probes the reorientation of dipolar tensors and allows the observation of slow molecular dynamics, in particular the determination of reorientation angles and rates. The dipolar coupling between two distinct spins is used to generate a DQ coherence, and the orientationdependent coupling is measured by means of the DQ MAS sideband pattern before and after a mixing time. In the course of a reduced threedimensional experiment, the two DQ sideband patterns are correlated, resulting in a DODO sideband pattern which is sensitive to the reorientation angle. By referencing the DODO time signal, the information content of the pattern can be divided into the sidebands and the centerband, with the former reflecting only the moieties which have undergone a reorientation, and the latter predominantly containing contributions from moieties which have remained in, or returned to, their initial position. Hence, a single sideband pattern provides access to both the reorientation angle and the relative number of moieties subject to the motional process. As a first example, such DQDQ MAS experiments were performed on the C13C13 spin pairs of an enriched poly(ethylene) sample. In its crystallites, the dynamics of a known chainflip motion were investigated, yielding a C13C13 reorientation angle of Delta theta (ij) = (70 +/ 5)degrees and an activation energy of EA = (100 +/ 20) kJ mol(1). (C) 2001 Academic Press.
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Documento generato il 03/04/20 alle ore 04:30:47