Approaches to the Physical Mechanisms and Theories of Low-Concentration Effects in Aqueous Solutions

The influence of optical, plasma, and mechanical effects on the macroscopic properties of aqueous solutions is discussed. An important role of the nano-objects that are spontaneously formed in a liquid or generated by external perturbation sources in the formation of these properties is stated. It is suggested that the presence of nano-objects in aqueous solutions determines the behavior of most various processes: from the formation of shock waves to the change in the ion composition and regulation of biological activity. Nonmonotonic dependences of the absorption and luminescence efficiency on the concentration of ion impurity centers in crystals are demonstrated. One of the causes of nonmonotonicity is the aggregation of active centers from neighboring lattice cells. Active aggregates are identified based on a thermodynamic calculation, in agreement with the spectral and relaxation experimental data. Particular analytical models of the thermodynamic state of water and aqueous solutions and the kinetics of chemical reactions occurring in them are reviewed. Here, a key point is the consideration of short-lived hydrogen bonds between water and solute molecules The formalism of the theory of dichotomous noise is used to describe these twinkling hydrogen bonds. Its application indicates, in particular, the possibility of forming a low-concentration droplet phase in solutions. A scheme of successive unification of particular models of thermodynamics and kinetics of aqueous solutions, based on an analogy with the theory of luminescence effects in ion impurity centers, is proposed.