Radiolysis phosphorescence

An important implication from Eq. 2 is that the observed phosphorescence spectra are (always) already relaxed within the time resolution of the measurement of phosphorescence spectra. Therefore, the true triplet energy (center of the triplet DOS) is always higher than the apparent phosphorescence spectra, which sets a lower limit only. For PF2/6 the true triplet level is calculated to be 2.26 eV instead of the observed 2.15 eV [24] from phosphorescence measurement. This higher value however agrees very well with that measured using the pulse radiolysis energy transfer technique which yields triplet energies in the initial unrelaxed state [71]. 

The reaction-rate constant kjfP is a chemical constant characteristic of a compound P with general validity. It can be measured in laboratory experiments designed to isolate the effect of a single environmental factor j. Often, for practical reasons, it is determined only relative to that of a well-studied model compound with an absolute rate constant known for the same reaction. In case of slow reactions it is generally easy to measure absolute rate constants directly. For the study of fast reactions, sophisticated short-time measurements, such as pulse radiolysis or flash photolysis, typically combined with kinetic absorption spectroscopy or kinetic phosphorescent measurements, must be applied. 

The effect of heavy atoms on the relative yields of fluorescence and phosphorescence has been investigated both by inserting Br and I substituents in the ring of deuterioporphyrin IX and its Zn derivative,340 and by adding ethyl iodide to the solution of a number of free base porphyrins.341 Other authors discuss the luminescence of protoporphyrin IX dimethylester after pulse radiolysis in benzene,848 and from monomeric and dimeric ethylenediamine-substituted protoporphyrin IX and some metal derivatives.343 Several reports consider the emission from porphyrins in Shpolskii matrices and other crystalline organic hosts.344-340... 

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