EFFICIENCIES OF O2((1)SIGMA(G)(+)) AND O2((1)DELTA(G)) FORMATION IN THE PRIMARY STEPS OF TRIPLET-STATE PHOTOSENSITIZATION IN SOLUTION

The primary steps of triplet state (T1) sensitization of singlet oxygen O2(1SIGMA(g)+) and O2(1DELTA(g)) by phenalenone (PH) and benzophenone phenone (BP) have been investigated in carbon tetrachloride by time-resolved measurements of the phosphorescence of T1, O2(1SIGMA(g)+) and O2(1DELTA(g)). Besides lifetimes, the detailed analysis of the transient curves yields absolute efficiencies a of O2(1SIGMA(g)+) and b Of O2(1DELTA(g)) formation in the primary energy transfer step from T1 to O2. For PH a = 0.62 and b = 0.37, for BP a = 0.11 and b = 0.26 were found. Collisional deactivation of O2(1SIGMA(g)+) by carbon tetrachloride, benzene, cyclohexane, trimethylpentane and methanol produces O2(1DELTA(g)) with efficiency c greater-than-or-equal-to 0.95.