Epr of Atoms and Radicals in Radiation-Damaged SolidH2and HD

Paramagnetic resonance of electronic states of atoms and radicals trapped in solid ${\mathrm{H}}_2$ and HD at 4.2°K after 4 × ${10}^6$ R of radiation damage have been investigated at 24 GHz. The apparent spin-lattice relaxation time of resonances of H atoms is damaged solid HD formed from gas containing 3 × ${10}^{-4\mathrm{}}$ ${\mathrm{O}}_2$ was found to be 0.14 msec at 4.2°K and approximately 0.27 msec at 1.2°K. Furthermore, these H atoms in solid HD remained stably trapped at 4.2°K for periods in excess of two months.