EPR study of the H2O2 interaction with TiO2; evidence for a novel S = 1 surface radical pair

H2O2 reacts with rutile TiO2 powder forming not only surface O2– anions but also two newly identified surface S = 1 triplet radical anion pairs composed of two interacting O–···O– centers characterised by the EPR spin Hamiltonian parameters of giso = 2.0104 and D = 13.7 mT for triplet 1 and giso = 2.0064 and D = 12.7 mT for triplet 2.