Vibronic Analysis of the ca. 400 nm Band of the Phenoxy Radical within the Approximation of the Weak Coupling Limit

The effect of vibronic coupling on the absorption band at ca. 400 nm as well as on the Raman spectrum of the phenoxy radical (The IUPAC nomenclature recommends phenoxyl. However, in spectroscopic studies most authors prefer phenoxy to phenoxyl.) is examined by ab initio MO calculations within the framework of the adiabatic approximation. The vibronic coupling effect is represented in terms of the linear non-Condon term in the analysis of the absorption band and in terms of the B-term in the Raman study. The inclusion of the coupling effect improves theoretical spectra fits to experimental spectra.