PHOTOPHYSICAL AND PHOTOCHEMICAL STUDIES OF PHENOTHIAZINE AND SOME DERIVATIVES - EXPLORATORY STUDIES OF NOVEL PHOTOSENSITIZERS FOR PHOTORESIST TECHNOLOGY

The photochemistry and photophysics of a series of phenothiazine derivatives have been examined by using a combination of time-resolved laser techniques. The triplet states, which are readily detectable by using laser flash photolysis techniques, decay with lifetimes in the neighborhood of 1-mu-s; these lifetimes are frequently influenced by self-quenching processes. All the phenothiazines are modest singlet oxygen sensitizers, with yields, phi-DELTA, in the 0.18-0.46 range. The rate constants for the reactions of both singlet and triplet states with bromo compounds correlate well with the free energy for electron transfer. Increased delocalization (e.g., by introduction of naphthalene moieties) shifts the ground-state spectrum to the red so that they show significant absorption at the mercury lamp g line; however, the rate constants for reaction with I (1,3,5-tris(2,3-dibromopropyl)-1,3,5-triazine-2,4,6-(1H,3H,5H)-trione) are reduced to a point where only singlet processes are likely to be of importance.