Deuteron spin–lattice relaxation experiments on α-crystallized toluene-d3 are reported. It is shown that the two distinct methyl groups existing in this crystal can be identified by 2H–T1 experiments. The temperature dependence of the broadenings is found to be different, particularly in an intermediate temperature range, where transitions to the second excited librational state dominate the dynamics for one type of methyl group. For the second type, the crossover from a low temperature behavior to a ‘‘quasiclassical’’ regime takes place in a very narrow temperature range. The apparent activation energies are compared to the known transition energies of protonated toluene.
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