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Pulsed NMR in solid D2. II. Stimulated echo

โœ Scribed by Xi Qin; David Clarkson; Horst Meyer


Publisher
Springer US
Year
1993
Tongue
English
Weight
766 KB
Volume
91
Category
Article
ISSN
0022-2291

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โœฆ Synopsis


A study of the NMR stimulated echo resulting from an rf. three-pulse sequence is presented for hcp D 2 with para-D2 concentrations X between 0.06 and 0.49 and over the temperature range 0.07 < T < 1.5 K. The echo has two components, a sharp one on top of a broad one, which are the signals of the I = 1 (p-De) and the I =2 (o-De) spins respectively. The echo widths reflect the different degrees of molecular orientational ordering. The echo amplitudes are studied as a function of the experimental parameters in the r.f. pulse sequence. The temperature dependence of the amplitude shows the expected Curie law behavior for the I =2 spins, but a strong deviation from this law for the I = 1 spins. This anomalous behavior is consistent with that found for the I = 1 solid echo signal. The echo decay time rE is found to be very different for both spin systems, both in magnitude and in temperature dependence. The comparison of the I = I spin results in D2 with those in H2, where the molecular orientational ordering is also from quadrupolar interaction, shows substantial differences. These are discussed in terms of the spin diffusion within each NMR line, and of the cross-relaxation between the two I = 1 and I =2 spin systems.


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