Title : Cluster structure and supercooling of water and alcohols
Abstract:
Molecular spectroscopy in combination with methods of matrix isolation of molecules in cryo-matrices allows us to obtain important information on the structure and mechanisms of phase transformations of such important substances as water and alcohols. In the liquid phase, water and alcohols are characterized by a cluster structure [1,2]. Such structural ordering allowed us to refer these objects together with liquid crystals to the class of partially structurally ordered liquids. This terminological innovation of ours was supported by grant No.2013 - 6720 of the Swedish Scientific Council (scientific supervisors Prof. Lars Pettersson (Sweden) and Prof. Valeriy Pogorelov.(Ukraine). With the use of vibrational spectroscopy, methods (FTIR and FTRaman) we have shown that at cooling of liquid water near the temperature of 00 C in its structure five molecular clusters predominate. Such structures are characterized by the 5th order symmetry axis. However, such five-molecular formations cannot be structural elements of crystalline water. Further lowering of water temperature leads to an increase in the number of hexameric clusters in its structure. Hexamers are characterized by the 6th order symmetry axis, and therefore they can be structural elements of solid water - ice. The presentation offered to the FAT 2025 participants’ shows:
1) When liquid water and alcohols are cooled near their melting point, a state of supercooling precedes the crystallization state.
2) When crystalline water and alcohols are heated near the melting point, the crystal-liquid phase transition occurs without intermediate states.
Analysis of FTRaman spectra of liquid water shows the presence of molecular associates in it. Since physiological liquids are often aqueous lyotropic liquid crystals, their structural features can influence the course of physiological processes in living organisms.
