Deuterium NMR spectroscopy of CD30D adsorbed on deuterated cellulose
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Date
1993
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University of New Brunswick
Abstract
The technique of pulse Nuclear Magnetic Resonance (NMR) was used to determine the T1, T1P, T2FID and T2CP deuteron relaxation times for deuterated methanol on deuterated cellulose ( with ad -methanol content of 0.198 grams of d - methanol per gram of cellulose ) . The temperature range studied was 133 K to 291 K using a resonant frequency of 30. 513 Mhz and a B1 locking field of 10G for the T1P measurements. The T1, T1P and T2CP relaxation times each had two components, and the T2FID relaxation time displayed a single component. The ratio of the fractions of the spins relaxing with the three long components to the fractions for the corresponding short components was seen to be approximately three to one; this is seen to relate the CD3 group to the long component, and the short component to the OD part of the methanol. The model used to describe the molecular motion was a bimodal distribution of correlation times, with the two modes corresponding to two distinct binding sites on the cellulose molecule. For room temperature , the correlation times ( Tc and activation energies calculated from this model are 6 . 8 x 10-10 s-1 , 2.000 kcals/mol ( tf, fast mode ) and 6.9 x 10-8 s-1 , 3.000 kcals/mol ( t5 , slow mode ) for the long component; for the short component, the calculated values are 3 .5 x 10-10 s-1 , 2.2 kcals/mol ( fast mode ) and 3.3 x 10-8 s-1, 1.000 kcals/mol ( slow mode ).