SPECTROSCOPIC MANIFESTATIONS OF FLAVOMONONUCLEOTIDE DIMERS IN POLYVINYL-ALCOHOL FILMS

Absorption and fluorescence spectra of flavomononucleotide (FMN) in po lyvinyl alcohol films (PVA) over a very wide concentration range are i nvestigated. The dimerization constant as well as the pure monomer and dimer spectra are calculated and the structural parameters of FMN dim er are established. Excitation wavelength and temperature dependencies of FMN/PVA fluorescence spectra for different FMN concentrations were carried out. These measurements together with those of absorption rev eal that dimers are imperfect traps for excitation energy and that the energy transfer can occur both in forward and in reverse direction. M oreover, it was shown that the observed temperature changes in fluores cence spectra may be qualitatively explained by the effect of inhomoge neous broadening of FMN energy levels and by the presence of fluoresce nt dimers. (C) 1998 Elsevier Science B.V. All rights reserved.