J=1 toJ=0D2conversion in solid D-T

J=1 to J=0 molecular rotational time constants for J=1 ${\mathrm{D}}_2$ in solid D-T at 1.8 to 14 K have been obtained by analyzing the longitudinal relaxation times ${\mathit{T}}_1$ of the tritons in the same sample. The inherent time constant in the electric quadrupole theory of ${\mathit{T}}_1$ is a function of both the J=1 ${\mathrm{T}}_2$ and J=1 ${\mathrm{D}}_2$ concentrations. By subtracting out the J=1 ${\mathrm{T}}_2$ behavior as obtained from pure ${\mathrm{T}}_2$ samples, the J=1 to J=0 ${\mathrm{D}}_2$ time constants remain. From 10 to 14 K, the ${\mathrm{D}}_2$ time constants are longer than those for ${\mathrm{T}}_2$ at constant temperature by the ratio of the nuclear magnetic moments. From 1.8 to 5.3 K, the two time constants are identical at about 5 h. A time-constant minimum occurs at about 10 K for both hydrogens. A rate-equation theory of rotational catalysis by free hydrogen atoms created by the tritium radioactivity is presented.