Conversion of Spin Species in Solid CH4through Level Crossing with Paramagnetic Impurities

Abstract

Measurements of proton spin-lattice relaxation times $T_1$ in $\gamma$-irradiated C${\mathrm{H}}_4$ at 1.1°K have been used to observe spin conversion. A strong magnetic field dependence of the conversion rate is found, with a sharp peak at 12.5 kOe and with some indication of a second peak at 15.2 kOe. The existence of the two peaks is tentatively interpreted as corresponding to transitions from a slightly split $T$ level ($J=0\mathrm{}$) to the ground $A$ level ($J=0\mathrm{}$).