PRERESONANCE RAMAN EFFECT OF SOLID-STATE PHENOTHIAZINE

The band intensities of Raman spectrum of PTZ in the solid state show a clear dependence on the laser excitation wavelength. Such a behaviou r, not observed when the spectrum is obtained from PTZ in solution, in dicates that in the crystal the molecular orbital of the compound is p erturbed to some extent. The PTZ . SO2 complex in solution presents th e same pre-resonance pattern as does solid PTZ, suggesting that the sa me PTZ orbital is involved in both cases. The most enhanced PTZ modes are those ascribed to the aromatic ring vibrations, indicating an inte raction through the pi molecular orbitals; it is proposed that PTZ act s as a pi-donor toward SO2 on the basis of the pre-resonance pattern o f the Raman spectrum of PTZ . SO2.