Atomic ESR relaxation in tritiated solid hydrogen.

Abstract

Electron-spin-resonance data taken at 9 GHz for hydrogen atoms in tritiated solid H[sub 2], HD, D[sub 2], D-T, and T[sub 2] are presented. Both linewidths and longitudinal relaxation times have been measured simultaneously with [ital J]=1 and hydrogen-atom concentrations. Data are presented to show that 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 line shapes that are more often closer to Lorenzian. The Gaussian theories may be useful only for a few data points taken with high [ital J]=1 concentration and at high temperature. A dilute-spin theory for atom-atom interactions when little [ital J]=1 hydrogen is present, fails to work as well. The best line-shape agreement is obtained with a combination of [ital J]=1 and atom concentrations, both to the half power. D[sub 2] fails conspicuously with every approach. The longitudinal relaxation times appear constant at 0.1--1 s except at low [ital J]=1 concentrations, where the relaxation times increase. The electric-quadrupole mechanism is postulated for low [ital J]=1 concentrations, but it does not show the expected [ital J]=1 dependence. No information on hidden'' atoms is forthcoming from these data,more » but their presence is still a possibility.« less