Oscillation spectra of seed NaCl crystals in aqueous solutions

Abstract

Using the flicker-noise method (FNM), we investigated the oscillations of clusters in aqueous solutions of NaCl in the range of concentrations from 0.1 to 26.0 mass %. It has been established that in the solutions oscillators whose masses are similar to the masses of the models of aggregates of solvate clusters of ion pairs (SCIP) of salt with a different water content are present. In diluted solutions (<10%), the elementary SCIP has the form NaCl⋅40H 2 O. For the entire range of concentrations the SCIPs are given by structures based on the cubic system of the sodium chloride system. The base structure for them is a cube formed from 12 SCIPs of salt. The largest cluster revealed by the FNM method for all investigated concentrations of salt had a mass of +1.5 million D. The presence of NaCl in water leads to a collapse of its cluster structure, except for the smallest clusters (H 2 O) 10...11 , whose concentration increases with temperature or solution concentration. The distribution of SCIPs changes dramatically at a temperature above 300 K. The possible structures of SCIPs are given and the mechanism of their formation is discussed. Keywords: oscillations of clusters in solutions, solvate clusters of ion pairs of salt, seed NaCl crystals, cluster-formation energy, distribution of clusters in solution, flicker-noise spectroscopy.Introduction. Understanding of the structure of solutions is a topical problem of chemistry and physics. This especially concerns nanostructures based on weak cooperative interactions with formation/destruction energies at the level of a few kJ/mole. Among them are the processes of cluster formation, equilibrium of seed-crystal formation [1], decomposition and formation of associates [2], and cooperative interactions in organized biological systems [3,4]. The energy effects of these processes are often below the sensitivity thresholds of most instruments used. Signals from weak interactions are masked by electronic instrumentation noise and energy fluxes from the outside, which complicates their identification and understanding. As we see it, this problem can be solved by using modern computers and familiar mathematical methods for "clearing" signals and representing large bodies of information in a form convenient for comprehension.Interacting objects of investigation can be weak interactions in a liquid, e.g., in water. It is known that the structure of water is an aggregate of tiny volumes with the structure of ice, polymer formations (H 2 O) n , and individual molecules ([5], p. 78), which are easily formed and destroyed under the action of very weak energy fluxes. For example, a water cluster (Fig. 1) composed of 280 molecules is a typical example of the problem of revealing and establishing the far nanostructure of a liquid.Analogs of larger clusters are known in physics and chemistry [4], and the problem of their role and identification is topical.With the use of the methods of X-ray spectroscopy of substances in the liquid state, periodic formations whose spectra are partially ide...

New Non-Destructive Method for the Analysis of Domains’ Distribution in Proteins and Biomatrices. Nature of Domains

“…The sequences of investigated clusters in natural waters [14], distilled water [5], polymers [7,15,16], solutions [17,18], protein coils and polysaccharides (lysozyme, L-arginine, chymotrypsinogen-A, amylopectin, etc. [6]) are characterized by similar masses.…”