Excited state dipole moments of N,N-dimethylaniline from thermochromic effect on electronic absorption and fluorescence spectra |
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Authors: | A. Kawski, B. Kukli ski,P. Bojarski |
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Affiliation: | Department of Mathematics, Physics and Informatics, Institute of Experimental Physics, University of Gdańsk, ul. Wita Stwosza 57, 80-952 Gdańsk, Poland |
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Abstract: | The effect of temperature on absorption and fluorescence spectra of N,N-dimethylaniline (DMA) in ethyl acetate has been studied for temperature ranging from 293 to 388 K. The permittivity ε and refractive index n of the solvent decrease with temperature increase and the absorption and fluorescence bands are blue shifted (so-called “thermochromic shift”). Based on this phenomenon, the dipole moment μe in the excited singlet state and the Onsager interaction radius a for DMA were determined using the Bilot and Kawski theory [L. Bilot, A. Kawski, Z. Naturforsch. 17a (1962) 621; 18a (1963) 10, 256]. For the known dipole moment in the ground state μg = 1.61 D and for /a3 = 0.54 ( is the polarizability of the solute) the average value of μe = 3.55 D and a = 3.1 Å were determined. The obtained values for DMA are compared with the experimental values determined by other authors. |
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Keywords: | N,N-dimethylaniline Thermochromic absorption and fluorescence band shifts Dipole moments in excited singlet state Onsager interaction radius Permittivity and refractive indexes of ethyl acetate at different temperatures |
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