Quantitative aspects of all-trans-retinol singlet and triplet quenching by oxygen

In benzene and methanol, the oxygen quenching of all-trans-retinol singlet results in intersystem crossing (enhanced) and energy transfer (to form 1O2*, 1Δg), both with quantum efficiencies considerably less than unity (0.3–0.5). 1O2* formation from retinol triplet quenching by 3O2 is closer to quantitative (≈ 0.8).