| Popis: |
The 1 H-relaxation times T 1 and T 2 of water and benzene adsorbed in zeolite beta have been measured as a function of temperature and/or the content. In case of water in as-synthesized and H-beta two minima of T 1 were observed. Proton exchange between the adsorbed water and OH-groups can be observed at about 270 K. The exchange time is near 2 ms. Motional narrowing starts at 180 K. In Na-beta only one T 1 -minimum was found. In case of benzene, motional narrowing starts at 220 K. Below 250 K, T 2 is about 70 μs indicating a fast rotation of benzene around the six fold axis. |
