Abstract
The proton NMR susceptibility, linewidth, T1, and spin conversion rates down to 0.4 K have been measured in (CH4)xKr1−x mixtures for 0.6<xproton susceptibility 〈I(I+1)〉 could be fitted with a mean tunneling splitting EAF=5.8 K, independent of x. The linewidth has been found proportional to (x)1/2 as expected for random dilution. At low T, a sharp increase in T1 around x=0.8 could be due to transition to an octupolar glass. An attempt has been made to explain in terms of existing theories the spectacular increase in conversion rate upon dilution.