Quenching of the first excited singlet state of substituted benzenes by nitric oxide

Abstract

Rate parameters are presented for the quenching of the first excited singlet states of a variety of substituted benzenes by nitric oxide in the vapour phase. These values are shown to be very similar to those for quenching by molecular oxygen where the results can be understood in terms of an encounter complex which is stabilized by charge-transfer from excited aromatic molecule to oxygen. Deviations from this similarity at high ionization potentials of the excited aromatic molecule are interpreted as being due to nitric oxide having a higher electron affinity than oxygen.