Unique deuteron spin echoes from HD and o-D2 in large crystal fields

Novel deuteron multiple spin echoes are observed from HD and {ital o}-D{sub 2} molecules trapped in hydrogenated amorphous silicon samples. The echo locations result from the combined action of intramolecular quadrupole and dipole couplings. Using molecular-beam values of the interactions, the observed echo times are predicted to within a few percent. For {ital o}-D{sub 2}, the echoes demonstrate mixing of {ital I}=0 and {ital I}=2, {ital m}=0 states. The existence of the HD and {ital o}-D{sub 2} echoes at low temperatures requires crystal-field admixture of higher {ital J} states into the rotational ground state of the molecules.