NMR-STUDIES ON SINGLE-CRYSTALS OF H-2 .1. CRYSTALLINE FIELD ENERGY FOR ORTHO-H2 IMPURITIES IN SOLID PARA-H2

Using NMR techniques on two single crystals of H2, we have determined the crystalline field Vc that splits the rotational ground state of isolated ortho-H2 molecules in para-H2. From the temperature-dependent splitting of the NMR doublet peak, we obtain an average {Mathematical expression} independent of ortho concentration X over the range between x= 0.1% and 1.5%. The experimental spectra, as a function of both T and the applied field orientation, can be fitted by a model where Vc has a Gaussian distribution about its average value with a standard deviation Vc289-03. This distribution might be caused by strains in the sample. The values of δVc are compared with those from previous experiments. © 1979 Plenum Publishing Corporation.