The effect of various polar solvents on the location of absorption and dual fluorescence (short wavelength emission, SE, and long wavelength emission, LE) of 4-(dimethylamino)benzaldehyde (DMABA) at room temperature was investigated. It was found that the fluorescence intensities ratio LE/SE is constant for concentrations ranging from 10(-5) M to 10(-1) M, which evidences that the LE-band is not of excimer origin. Based on the batochromic shift of electronic spectra of DMABA and Bilot-Kawski theory the values of excited state dipole moments in SE: mu(SE)(e) = 7.6 D and the Onsager radius a = 4.3 angstrom were found using the known from literature value of ground state dipole moment mu(g) = 5.6 D. For the emitting twisted intramolecular charge transfer (TICT) excited state the value of mu(SE)(e) = 12 D was found. (C) 2007 Elsevier B.V. All rights reserved.