| Low concentration ortho-hydrogen and para-deuterium in solid phase were studied by various proton NMR measurements. The FID's and lineshapes, solid echoes, T(,1) and echo decay times were obtained as functions of temperature from 4K to 0.05K in the low concentration of oH(,2) and from 4K to 0.1K in the low concentration of pD(,2) solids as well as concentration. The FID's in the hydrogen samples (0.2-1.0%) showed the pairing process below 0.1K. For the deuterium solids (4%) various NMR pulse sequences were applied to study the rotational substates of J=l molecules. Data obtained in those experiments were then compared with the results of others and theories. However, some of our data were the first attempt in the low concentration of J=l molecules. From those experiments it was found that the rotational fluctuation in solid echo measurements was very important especially in the long pulse interval to understand the echo formation. |
