| Popis: |
The lock-in detected proton NMR-signals of methyl groups in solids is considered at arbitrary temperatures of the spin system. In the high temperature approximation the results reduce to those of Goldman and others, extended with coupled spin-lattice relaxation equations. At low temperatures of the tunnelling system some quite unusual features are to be expected, due to spin symmetry conversion causing time- as well as temperature-dependent lineshape and deviation of the magnetization from the Curie law. In particular, the lock-in detected signals in the absorption and dispersion modes are discussed. |
