Luminescence of Molecules with Internal Charge Transfer upon Longwave Excitation

Abstract

We have studied the spectral properties of luminescence of laurdan molecules in glycerin upon excitation at the red edge of the absorption band at different temperatures. The most significant red-wave shift of the spectra (∼10 nm) for the longwave band of dual fluorescence is observed depending on the excitation wavelength at a low temperature of 260 K when a solvent forms a fairly rigid matrix. At the same time, at increased temperatures of up to 370 K a small bathochromic shift and a change in the shape of the luminescence bands are also recorded reliably. Changes in the excitation spectra were observed when luminescence was recorded in the bands of the LE- and CT states. The difference spectrum responsible for the additional absorption that does not make a contribution to the longwave luminescence component has been isolated. The decay kinetics of both luminescence components have been measured and their expansions in decay constants have been analyzed. The experimental dependences obtained point to the complex mechanism of inhomogeneous broadening of spectra.