MECHANISM ON THE EFFICIENT FORMATION OF SINGLET OXYGEN BY ENERGY-TRANSFER FROM EXCITED SINGLET AND TRIPLET-STATES OF AROMATIC-HYDROCARBONS

The formation efficiencies of singlet oxygen for the oxygen quenching in excited singlet of aromatic hydrocarbons; A and for the quenching in the triplet T1; B were estimated. The hydrocarbons were classified into three types: (i) A = 1 and B = 1 for dicyanoanthracene i.e., total 200% efficiency, (ii) A almost-equal-to 0.3 and B = 1 for anthracene, (iii) A almost-equal-to 0 and B = 1 for pyrene, as examples. It is suggested that the energy levels of T2 and a dissociative exciplex; (T1(1)DELTA-g) correlated to A and B values from the energetic considerations.