For three fractions of humic acids HA of different molecular weight, isolated from one soil, spectral dependence of fluorescence self-quenching constants KSQλ was studied. It was established that each fraction is characterized by individual spectral dependence of the self-quenching efficiency. The following experimental fact is thus established: for initial macromolecules HA, which have strong hydrophobic properties, the efficiency of self-quenching of "red" fluorescence is higher than "blue" fluorescence of this fraction, and for initial macromolecules HA, which have weaker hydrophobic properties, efficiency of self-quenching of "blue" fluorescence is higher than for "red" fluorescence of this fraction. Thus, for self-association HA process, using a technique of observation of spectral self-quenching, the information on changes in fluorophores in this process is received for the first time.
fractions of humic acids, fluorescence, self-quenching, constant of Stern-Volmer, spectral dependence