Correlation Analysis of the Shifts of the Electronic Spectra of Anthracene, Phenanthrene, and Fluorene as Functions of the Temperature in the Gas Phase and of the Refractive Index in n-Paraffin Solvents

摘要

The temperature-induced shifts of the maxima of the longest-wavelength bands of the S_(1) <- S_(0) and S_(2) <- S_(0) transitions in phenanthrene and the S_(1) <- S_(0) transition in fluorene in the gas phase are measured. A correlation analysis of these data and similar data on the S_(1) <- S_(0) and S_(1) -> S_(0) transitions in anthracene is fulfilled. The positions of the maxima of analogous bands of the S_(1) <- S_(0) transition in anthracene, S_(1) <- S_(0) and S_(2) <- S_(0) transitions in phenanthrene, and S_(1) <- S_(0) transition in fluorene dissolved in liquid n-paraffins are also measured and analyzed as functions of (n~(2) - 1)/(n~(2) + 2), where n is the refractive index of the solvent. The results confirm the conclusion of the Mirumyantz-Demchuk theory about the linear temperature dependence of the wave number of a band maximum but contradict the prediction that, upon extrapolation to T velence 0 K, the positions of the maxima correspond to the electronic transitions in the molecule unperturbed by out-of-plane vibrations of the aromatic core.