EXCITED-STATES IN SOLID PHENOTHIAZINE AS STUDIED BY ELECTROABSORPTIONSPECTROSCOPY

Electric field modulated absorption spectra of vapor deposited layers of phenothiazine, explained in terms of a quadratic Stark effect, indi cate modification of intramolecular (Frenkel-type) excitons by charge transfer transitions throughout UVIS absorption spectrum in the range 250-450 nm. The charge transfer character of the excited states appear s at energies characteristic of various oxidation products of phenothi azine as identified from a spectroscopic study of photochemical air ox idation, performed on solution and solid him samples of this compound. Tile charge transfer transitions are ascribed to electron transfer be tween the molecules of phenothiazine and their oxidized species create d in the samples during preparation and handling procedures.