Theory of NMR multiple echoes in solid hydrogen

Abstract

We have examined the theory of NMR multiple echoes developed for solid3He to determine whether multiple echoes could be observed in solid hydrogen. We were particularly interested in the possibility of testing for low frequency quantum tunneling motions in solid hydrogen by the observation of multiple echoes. We find that for easily accessible nuclear spin polarizations, P > 12%, multiple echoes would be observed for HD impurities in solid parahydrogen if motional narrowing is effective in increasing the HD nuclear spin-spin relaxation time T2 to the order of 1 msec. These values for T2, which have been observed for HD impurity concentrations of the order of 1%, are larger than the calculated rigid lattice values and can be attributed to quantum tunneling at frequencies of the order of 1kHz.