NUCLEAR-SPIN-LATTICE RELAXATION-TIMES FOR H-2 IN SOLID NONMAGNETIC HOSTS

We calculate the nuclear-spin relaxation times T1 and T2 for isolated ortho (J=1) H2 molecules in solid nonmagnetic hosts located at sites with various crystal fields. The mechanism considered for the relaxation of a nuclear spin to lattice equilibrium proceeds via the molecular angular momentum and is valid in the limit where molecular spin-lattice decay rates are much greater than molecular-nuclear-spin coupling frequencies. We find that many relaxation properties, including the value of T1 at the T1 minimum and the product of T1T2 at temperatures well below the temperature of the T1 minimum, depend crucially on the crystal field at the H2 molecular site. Thus measurements of T1 and T2 can yield definite information about the environment of H2 molecules in a host lattice. © 1979 The American Physical Society.