Ergosterol (provitamin D2) triplet state: an efficient sensitiser of singlet oxygen, O2(1 delta g), formation

The triplet state of ergosterol (provitamin D2) has been produced in benzene by pulse radiolysis and characterised in terms of absorption spectrum, lifetime, self-quenching properties and relaxed triplet energy. The amount of singlet oxygen, O₂(¹Δ_g), produced as a consequence of the oxygen quenching of this species has been determined by kinetic infrared emission spectroscopy. Ergosterol is significantly more efficient as a singlet oxygen sensitiser in benzene than is naphthalene, the absolute standard employed in this work.