ATOMIC ESR RELAXATION IN TRITIATED SOLID HYDROGEN

Electron-spin-resonance data taken at 9 GHz for hydrogen atoms in trit iated solid H-2, HD, D2, D-T, and T2 are presented. Both linewidths an d longitudinal relaxation times have been measured simultaneously with J = 1 and hydrogen-atom concentrations. Data are presented to show th at the line shapes can be inhomogeneous. Linewidth calculations using the weak dipolar interaction and hyperfine interaction are presented. Both predict Gaussian lines, and agreement is poor with the measured l ine shapes that are more often closer to Lorenzian. The Gaussian theor ies may be useful only for a few data points taken with high J = 1 con centration and at high temperature. A dilute-spin theory for atom-atom interactions when little J = 1 hydrogen is present, fails to work as well. The best line-shape agreement is obtained with a combination of J = 1 and atom concentrations, both to the half power. D2 fails conspi cuously with every approach. The longitudinal relaxation times appear constant at 0.1-1 s except at low J = 1 concentrations, where the rela xation times increase. The electric-quadrupole mechanism is postulated for low J = 1 concentrations, but it does not show the expected J = 1 dependence. No information on ''hidden'' atoms is forthcoming from th ese data, but their presence is still a possibility.