Classical and quantum molecular dynamics of cation in (CH3NH3)3Sb2Br9 polycrystal as studied by 1H NMR
✍ Scribed by Wojciech Medycki
- Publisher
- Elsevier Science
- Year
- 1999
- Tongue
- English
- Weight
- 190 KB
- Volume
- 14
- Category
- Article
- ISSN
- 0926-2040
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✦ Synopsis
1 Ž . H spin-lattice relaxation times and second moments were determined for polycrystalline CH NH Sb Br sample in a 3 3 3 2 9 Ž . 2 Ž . wide range of temperature 5-200 K at 24.6 and 55.2 MHz. H NMR spectra of CD NH Sb Br were recorded between 3 3 3 2 9
5 K and room temperature. The relaxation time is interpreted as a result of motion of two different non-equivalent types of monomethylammonium cations occurring at the 2:1 proportion in a unit cell. Below 30 K, the relaxation processes via tunneling are suggested to dominate. Above 30 K, only classical behaviour of methylammonium cations is detected. Two monomethylammonium cations relax with the classical correlated C reorientation and the rotational tunnelling mechanism, 3 while the third cation exhibits only the classical correlated reorientation. The dynamic parameters of these motions have been determined.