The measurements of correlation times of molecules adsorbed on silica gel,alumina and charcoal using NOESY and MAS NMR |
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| Authors: | Y Xue Y -R Du C -H Ye Y -H Kong |
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| Institution: | 1. Laboratory of Magnetic and Atomic and Molecular Physics, Wuhan Institute of Physics, 430071, Wuhan, P.R. China
2. Hubei Institute of Chemistry, Wuhan, P.R. China
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| Abstract: | The correlation times (τc) and cross relaxation rates of toluene, dimethylformamide, tetrahydrofuran, water-acetone and water-dioxane adsorbed on silica gel, alumina and charcoal were obtained by measurements of the integrated intensities of cross and diagonal peaks in their NOESY spectra. The (τc) of the above mentioned systems is in the range of 10?6?10?9 s, much longer than that in the liquid (10?12?10?14 s). It was found that intramolecular rotation of toluene adsorbed on charcoal is slower than that on SiO2, Al2O3 and the inversion of α and β protons in tetrahydrofuran is very fast (τc = 1.76×10?9 s). The cross relaxation plays an important role in the relaxation of molecules adsorbed on solid surfaces with low electron densities. |
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