Spin—Lattice Relaxation in Organo—Sulfur Radicals

Spin—lattice relaxation times (T1) of various organo—sulfur radicals, each with a different spectroscopic splitting factor g, were measured mainly at 77°K by the method of microwave saturation in electron spin resonance. All these radicals showed T1's which are smaller than those of organic (carbon) radicals. A remarkable correlation was found to exist between T1 and Δgmax, the maximum deviation of the g factor of a free radical from the free spin g value. These results have led to a conclusion that the spin—lattice relaxation in organo—sulfur radicals takes place mainly through spin—orbit and orbit—lattice coupling.