ESE-DETECTED EPR OF TRIPLET RADICAL PAIRS PRODUCED BY MECHANOCHEMICALTREATMENT OF 2,6-DI-T-BUTYLQUINONE DIAZIDE MIXED WITH 3,5-DI-T-BUTYLPYROCATHECHON

Electron spin echo experiments at high microwave frequency (95 GHz) ha ve been performed to study mechanically induced radical pairs. It is s hown that the sign of the spin-spin interaction of the radical pairs p roduced by mechanical treatment of a crystalline-powdered mixture of 2 ,6-di-t-butylquinone diazide and 3,3-di-t-butylpyrocathechon is positi ve. The asymmetry of the relaxation rates between the triplet sublevel s is explained by the presence of a nearby singlet state.