A general formula for the difference of solvent shifts of fluorescence and absorption spectra in the approximation of long range dipolar interaction was derived using Ooshika’s theory of light absorption in solution. Measurements of fluorescence and absorption spectra of some naphthalene derivatives in various organic solvents were undertaken, and the data were analysed by the theoretical formula. The formula reproduces the experimental data satisfactorily, and from this fact it was concluded that the most predominant factor which determines the difference of solvent shifts of fluorescence and absorption spectra of these molecules is the interaction energy between solute and solvent molecules due to orientation polarization. The incremental values of dipolemoments in the excited state were estimated, and those for α-, β-naphthols and β-naphthyl methyl ether were interpreted as due to the increase of electron migration from the substituent in the excited state.

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1. The fluorescence and absorption spectra of aqueous solutions of quinoline, acridine and 2,8-diaminoacridine were observed at various pH values, and it became clear that the stabilization energy by proton addition is larger in the excited state than in the ground state. 2. The effects of hydrogen bonding and proton addition upon the spectra were confirmed to be the same in tendency. 3. On the basis of the fluorescence intensities in various organic solvents, some discussions were made about the contribution of non-bonding electron to the inner quenching of fluorescence. 4. The vapor spectrum of quinoline was-taken and line spectra were observed, which are most certainly attributable to n→π* transition.

1. The absorption and fluorescence spectra of α-, β- naphthols and related compounds were measured in various mixed solvents in connection with the hydrogen bonding phenomena. The observed spectral shifts of absorption and fluorescence spectra, which were almost the same (∼30 Å), could be solely attributed to the hydrogen bonding effect. 2. It was found that the fluorescence intensity becoms stronger by hydrogen bonding when dioxane and acetic acid esters other than ethylchloroacetate are used as the proton acceptors. In the case of β-naphthol, it was established that the rate of inner quenching is decreased by hydrogen bonding. When ethylchloroacetate was used as a proton acceptor, fluorescence quenching was observed, which is also to be attributed to hydrogen bonding. 3. For β-naphthol, the measurement of the relative intensity established the fact that a new and different equilibrium state of hydrogen bonding, which shifts somewhat toward association, is reached during the life time of the excited state. 4. The mechanism of hydrogen bonding was discussed on the basis of the theory of electron migration, and it was concluded that the observed extra-stabilization of the hydrogen bond in the excited state as compared to the ground state, is mainly due to the increase of electron migration in the former state.