Solvent Stark Effect and Spectral Shifts. II

Solvent shifts of the energies of the lowest ${}^1{L}_a$ bands of the electronic absorption spectra of anthracene, chrysene, phenanthrene, and tetracene and of the lowest ${}^1{L}_b$ bands of the electronic absorption spectra of naphthalene, phenanthrene, chrysene, and picene are reported. The origins of these shifts are analyzed in terms of theories developed by Baur and Nicol and by Abe. Satisfactory fits of the experimental data are obtained for theoretical expressions derived from the theory of Baur and Nicol. The magnitudes of the parameters of this theory, which relate solvent shifts to the dielectric constant and refractive index of the solvent, are the same within experimental precision for the ${}^1{L}_a$ transitions in all of the molecules studied. A similar regularity of the parameters also is observed for the ${}^1{L}_b$ transitions. The theoretical expression for polar‐solvent shifts derived by Abe is found to overestimate the contribution of the permanent dipoles of the solvent molecules.