MAS NMR studies of carbon-13 spin exchange in durene
| Autor: | Zbiegniew Olejniczak, Zeev Luz, Raphy Poupko, Guenter Hempel, Piotr Tekely, Detlef Reichert |
|---|---|
| Rok vydání: | 1998 |
| Předmět: |
Carbon Isotopes
Nuclear and High Energy Physics Self-diffusion Magnetic Resonance Spectroscopy Radiation Molecular Structure Durene Carbon-13 Analytical chemistry General Chemistry chemistry.chemical_compound chemistry Benzene Derivatives Magic angle spinning Spin diffusion Molecule Condensed Matter::Strongly Correlated Electrons Magnetization transfer Instrumentation Spin-½ |
| Zdroj: | Solid State Nuclear Magnetic Resonance. 13:137-148 |
| ISSN: | 0926-2040 |
| DOI: | 10.1016/s0926-2040(98)00085-x |
| Popis: | One- (1-D) and two-dimensional (2-D) carbon-13 NMR exchange measurements in powder samples of isotopically normal durene under magic angle spinning (MAS) are reported. The experiments include rotor synchronized 2-D exchange (RS2DE), 1-D magnetization transfer (MT) and time reverse ODESSA (tr-ODESSA). The latter two experiments were performed as a function of several external parameters, including proton decoupling field during mixing time, sample spinning rate and partly, of temperature. The effects of these parameters on the spin exchange induced by spin diffusion and by chemical, or physical exchange, is discussed. Spin exchange between all types of carbons in the durene molecules occurs on the time scale of seconds. From the dependence of the spin exchange rate on the external parameters it is concluded that the process is dominated by spin diffusion. On the basis of these results an upper limit of 10 −16 cm 2 s −1 can be set for the self-diffusion constant in crystalline durene. |
| Databáze: | OpenAIRE |
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