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.

Solvent Effects upon Fluorescence Spectra and the Dipolemoments of Excited Molecules

The solution of the quantum‐mechanical eigenvalue problem is discussed for cases when a series of approximate eigenfunctions is known. If these ``unperturbed'' states are divided into two classes, a perturbation formula is derived giving the influence of one class of states on the other in the final solution. The formula contains as special cases: (i) the Schrodinger‐Brillouin formula for the eigenvalue of a nondegenerate state, (ii) a new simple formula for treating a class of degenerate states, and (iii) the splitting of the secular equation in cases where the system naturally consists of two independent parts in mutual interaction.

https://tu-freiberg.de/sites/default/files/media/institut-fuer-theoretische-physik-10451/Lehre/GrundlagenHLT/jchemphys_19_1396.pdf

A Note on the Quantum‐Mechanical Perturbation Theory

1) The ultraviolet absorption spectra of biphenyl in the crystalline state, in the solution state, and in the vapor state have been discussed in detail. 2) The relation between the position of conjugation band in the spectra of biphenyl and the spatial configuration of the molecule has been clarified by calculations based on the simple LCAO molecular orbital method. 3) By using the results of the calculations, it has been inferred from the analysis of the absorption spectra that the angles between the planes of the two benzene rings in the most probable conformations of biphenyl in the solution state and in the vapor state are about 20°C and about 40∼43°C, respectively. These values coincide fairly well with the values estimated by other workers on different grounds.

Relations between Electronic Absorption Spectra and Spatial Configurations of Conjugated Systems. I. Biphenyl

https://iopscience.iop.org/article/10.1088/0034-4885/8/1/312/pdf

Molecular electronic spectra, dispersion and polarization: The theoretical interpretation and computation of oscillator strengths and intensities

(1956). Quantum theory of cohesive properties of solids. Advances in Physics: Vol. 5, No. 17, pp. 1-171.

Quantum theory of cohesive properties of solids

The intensification of ultraviolet absorption in substituted over unsubstituted benzene is here attributed to the destruction of the sixfold symmetry of the benzene by the partial migration of an electron to the ring or out of it. Toluene, aniline, phenol, and fluorobenzene are treated. The electric moment produced by a migration of an electron from the radical into the benzene ring is calculated by the method of antisymmetric molecular orbitals and the extent of migration by a minimum condition. The results are in agreement with empirical data. It is concluded that a radical will produce a large intensification of the absorption if it has a low ionization potential, a pair of nonbonding P electrons, and a not too large ring‐radical distance. On this basis the SH group is predicted to be very effective.

A. L. Sklar

Papers

The Near Ultraviolet Absorption of Substituted Benzenes