The frequency and temperature dependences of the 1H NMR relaxation rates T1 -1for rotating CH3 groups in solids look quite anomalous at intermediate hindering potential barriers. In order to explain the experimental behaviour and to extract parameters from the NMR T1 experiments that account for tunnelling at low temperatures and random reorientation at elevated temperatures, we have calculated T1 -1vs. T-1 curves to be expected under various conditions. New experimental results for methyl iodide, methyl bromide, 3-methylthiophene, p-xylene, and methyl isocyanate have been fitted by this procedure and all the parameters that describe the motional behaviour have been derived. The single particle rotational potential has been determined using the first two terms of the Fourier expansion.
No takes yet. Share an insight, caveat, or question.
Langen et al. (1987) studied this question.