After UV irradiation at 77°K of dizoanthrone (I) one can observe the EPR spectrum characteristic of the triplet ground state of carbene anthronylidene (II). The values of the zero-field splitting parameters D and E are determined for two cases: in the parent matrix of (I), and in a benzophenone glass. In the dizaoanthrone matrix, two lines have structure which alters in a reversible manner between 77°K and 130°K.
