Knowledge Bank

The formation of $O2$ ($\mathrm{<mrow\; data-mjx-texclass="ORD">1</mrow>}\Sigma g+$) through sensitization by the triplet state of certain aromatic molecules has been previously demonstrated. The higher energy state of $O2(1\Sigma g+)$, however, has not been previously observed in sensitization. Using a time-resolved flash photolytic technique we have been able to demonstrate through its emission at 7620\AA the formation of $O2(1\Sigma g+)$ by energy transfer from the triplet states of several aromatic molecules including 1-fluoronaphthalene perfluoronapthalene, naphthalene, phenanthene, benzene, and benzaldehyde. We have also demonstrated that excited $SO2$ sensitizes the formation of $O2(1\Sigma g+)$ but the evidence points to the sensitizing state as a vibrationally excited singlet state, most likely $SO2(1B1)$, according to the reaction $SO2(1B1)v+O2(2\Sigma g-)-SO2(3B1)+O2(1\Sigma g+)$.