Photoionization delayed fluorescence

The photooxidation of p-phenylenediamine to the Wurster s Blue radical cation apparently proceeds by photoionization of the excited triplet state of the neutral molecule,219 and it has been suggested that the delayed fluorescence of perylene may be partly due to photoionization of its triplet state and slow subsequent recombination of... 

Triplet solute states ( A ) are formed only in these reactions. Since, typically, electron scavenging reaction (20) is faster than hole scavenging reaction (21), reactions (22) and (23) account for most of the delayed solute fluorescence. In the first few nanoseconds, only reactions (19) and (22) are important. Reaction (24) is important only in the studies on solute photoionization in hydrocarbons. The 3A -I- 3a annihilation is a minor source of delayed fluorescence, though there have been reports to the contrary. 

Slow dissociation rates (10 -10 s ) have been measured in Dunbar s laboratory by time-resolved photodissociation, which consists of trapping ions in an ICR cell during a variable delay time after a phot-odissociating photon pulse. The technique called time-resolved photoionization mass spectrometry , developed by Lifshitz, consists of trapping photoions in a cylindrical trap at very low pressure to avoid bimolecular collisions, and then ejecting them into a mass filter after a variable delay covering the microsecond to millisecond range. When the dissociation rate constant becomes lower than ca. 10 s competition with infrared fluorescence takes place and limits the lifetime of the decomposition process. This has to be taken into account to extract the dissociation rate constant from the experimental data. 

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