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Measurement of the wavelengths for the absorption maxima in a series of structurally similar dyes and relating the results to the calculated wavelengths for electronic transitions between highest filled and lowest unfilled electronic energy levels predicted by the free electron model.

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Results are presented from an investigation of the Raman and ultraviolet spectra of CBr4 in solutions containing benzene and from an ultraviolet investigation of the tetrahydrofuran-CBr4 system. The changes occurring in the ultraviolet spectrum for these systems have been analyzed quantitatively to determine the formation constants for one-to-one donor-CBrd complexes. Relative Raman intensity values are presented for three of the four CBr4 fundamentals in benzene-CBr4 solutions. These data were analyzed and interpreted in terms of complex formation, and the formation constants from this analysis were compared to those from the ultraviolet study. The two sets of formations constants agree, leading to the conclusion that formation of the same chemical species causes the observed changes in both the ultraviolet and the Raman spectra of CBr4 in benzene. The changes in the Raman intensities for CBr4 in solution with benzene are analyzed in terms of changes in the bond polarizability parameters, with results similar to those found earlier for solutions of Cc4 in donor solvents. The nature of the benzene-CBr4 interaction is discussed, and it is concluded that it is probably primarily electrostatic.The values of quantum yields of production of Fe(II), GFe(II), are about an order of magnitude lower in the microcrystalline solid compared with solution values, ranging between about 0.07 and 0.17 and increasing with increasing intensity and with decreasing wavelength. Values of GCo(I1) in the microcrystalline solid vary between about 0.07 and 0.55, are somewhat less than values for solutions, and are independent of intensity, but decrease with increasing exposure at the shorter wavelengths. It is suggested that hole-electron pairs are generated within the crystals; these subsequently generate radical ions at the surface.