Application of luminescence methods in the study of the structure of aqueous electrolyte solutions

Luminescence methods have been applied to the study of solutions of concentrated aqueous electrolytes of LiCl, CaCl2, LiBr, CsCl et al. with addition to those of LnCl(3), NICh(2), MnCl2. The rate constants of energy transfer from Tb(III) ions to Er(III), Ni(II), Mn(II) were measured in solutions of different electrolytes. So as the energy transfer rate depends on the distance between the energy donor and acceptor, it can be shown from this study, that the labile nanostructures of lanthanide ions are formed in concentrated aqueous solutions of LiCl and to a lesser degree in solutions of CaCl2. The concentration of lanthanide ions in labile nanostructures is close to that of a saturated aqueous solution of LnCl(2), The labile nanostructures consist of no less than several tens of lanthanide ions which exchange with ions of the solution during the time of less than one Cls The mixed labile nanostructures of lanthanide and Ni(II) or Mn(II) ions are also formed in concentrated LiCl solutions, but they are less stable. The dependence of labile nanostructure stability on temperature and on the addition to the electrolyte solution of other multicharge cations was also studied. The nature of the phenomenon of the labile nanostructure formation is discussed. (C) 2001 Elsevier Science B.V. All rights reserved.