Nuclear spin echo experiments in solid H2

Measurements of the nuclear spin echo decays are reported in solid H₂ after two-pulse and three-pulse sequences. The characteristic times T₂ and τ_E describe the spin-spin interaction and the stimulated echo decay respectively. A sharp increase in τ_E is observed upon cooling into the long-range orientationally ordered phase, and a continuous one during freezing into a quadrupolar glass. However, no significant change is observed for T₂ during either process.