Singlet oxygen infrared luminescence: unambiguous confirmation of a solvent-dependent radiative rate constant

A combination of time-resolved and steady-state infrared emission techniques, together with thermal lensing and 1,3-diphenylisobenzofuran bleaching experiments, in both benzene and cyclohexane, has confirmed that the magnitude of the singlet oxygen, O{sub 2}({sup 1}{Delta}{sub g}), radiative rate constant, k{sub r}, is indeed solvent dependent. It is therefore imperative that determinations of O{sub 2}({sup 1}{Delta}{sub g}) yields by comparison of infrared luminescence intensities, in either steady-state or time-resolved modes, be confined to comparisons to photochemical systems located in a single medium.