0000000000547772
AUTHOR
Wolfgang Liptay
Quantitative interpretation of the red edge excitation (REE) effect of 9,9′-bianthryl in polyisobutene by band shape analysis of the temperature-dependent optical fluorescence spectra
Optical fluorescence spectra of 9,9′-bianthryl (BA) in polyisobutene (PIB) were measured as a function of the excitation wavelength at various temperatures between 210 and 293 K. Irradiation at the red edge of the absorption spectra selectively excites distinct conformers with respect to the torsional angle. This leads to a strong dependence of the vibronic band shape of the fluorescence spectra on the excitation wavelength. The marked temperature dependence of the band shape may be attributed to the viscosity-dependent deceleration of the torsional relaxation of BA in the highly viscous polymer which prevents the excited state ensemble from reaching thermal equilibrium. The predominant bro…
Excited state dipole moments and polarizabilities of centrosymmetric and dimeric molecules. I. Model study of a bichromophoric molecule
Abstract Refractometric, dielectric and electro-optical absorption measurements are reported for 1-dimethylamino-2,6-dicyano-4-methyl-benzene (I) and 1,4-bis(4′-dimethylamino-3′,5′-dicyanophenyl)bicyclo[2.2.2]octane (II). The evaluation leads to dipole moments and polarizabilities of the ground state as well as the first dipole allowed singlet state. The experimental res excellently substantiate the method of electro-optical absorption measurements in solution. It is shown that the excited dimer wavefunctions of the bichromophoric molecule II localize by solvent induced local site perturbations.