Calculation of rotational T2 relaxation in solid parahydrogen and orthodeuterium

The shifts, the relative intensities, and the linewidths of the rotational Raman spectrum of solid parahydrogen (p-H2) and orthodeuterium (o-D2) are calculated by combining the memory-function formalism and a second-order perturbation treatment of the electric-quadrupole–quadrupole interaction. Lattice vibrations are neglected in the present theory. The linewidth is shown to represent the phenomenological T2-dephasing relaxation time, an upper bound of which can be set at ≈600 ps for p-H2 and ≈100 ps for o-D2. It is shown that at low pressure, the present theory compares favorably with the spontaneous Raman measurements on this solid.