%0 Journal Article
%T Self
%A Nikolay L. Lavrik
%A Nikolay M. Bazhin
%J Applied Spectroscopy
%@ 1943-3530
%D 2019
%R 10.1177/0003702819829809
%X The ultraviolet每visible (UV每Vis) spectra of the aqueous solutions of humic acids (HA) Aldrich were obtained within the concentration range 1每20ˋmg/L (0.1每2ˋ10每6ˋmol/L). A conclusion on the existence of the self-association (dimer formation) of HA macromolecules is based on the deviation of the concentration dependence of optical density (OD) from the linear one at [HA]ˋ>ˋ10ˋmg/L (>10每6ˋmol/L). An original, mathematical algorithm is proposed to determine a dimerization constant K and a molar coefficient of dimer absorption ˋ ˋ D ( 竹 ) The value of K was (2.56ˋ㊣ˋ0.07)ˋˋˋ106ˋL/mol. The calculated molar coefficients of HA macromolecule dimer absorption, ˋ ˋ D ( 竹 ) , indicate an increase in the dimer extinction coefficient ˋ ˋ D ( 竹 ) compared to the double value of the molar monomer absorption 2 ˋ ˋ M ( 竹 ) . It was established that the spectral dependence of the value 汕ˋ=ˋ ˋ ˋ D ( 竹 ) / ˋ ˋ M ( 竹 ) exhibits a minimum within a wavelength range of 300每450ˋnm, which is due to the difference in the efficiency of the interaction of various sites upon HA macromolecule dimerization. Thus, an approach of studying the processes of self-association is proposed using the method of UV每Vis absorption spectroscopy. This method is implemented for molecules that do not have characteristic absorption bands. The proposed method can also be successfully applied to molecules with characteristic absorption bands
%K Ultraviolet每Visible
%K UV每Vis absorption spectra
%K Aldrich humic acid
%K dimerization constant
%K molar dimer absorption coefficient
%U https://journals.sagepub.com/doi/full/10.1177/0003702819829809