Influence of microwave radiation on the association processes of rhodamine 6G molecules in aqueous solutions

Abstract

UDC 532. 74:547.97 The influence of the microwave radiation of two frequency ranges (2.0 mm and 6.9 dm) on the absorption spectra of the cationic dye rhodamine 6G has been investigated. A reversible decrease in the quantity of the dimers of the dye molecules after exposure of its aqueous solution to microwave radiation and also the phenomenon of destruction of the associates of the dye molecules under the influence of the microwave field have been revealed. They are discussed from the standpoint of the structural characteristic features of water.Introduction. Investigation of the influence of low-intensity microwave radiation on the structural characteristic features of aqueous systems has been of interest to specialists in the fields of biology and medicine for many years. This is associated with the attempts at explaining the influence of external fields on real biological systems and live tissues via a change in the structure of water, which is an indispensable component of the biological world.The main contemporary experimental and theoretical works devoted to the study of the influence of microwave radiation on aqueous systems have been considered in rather great detail in [1][2][3][4]. Attempts have also been made in these works to explain the effect of microwave radiation on water on the basis of models and investigation of the change in the spectral properties of water and results effect of the microwave field on natural objects. Earlier [5], another method of registration of the interaction of microwave radiation with a substance -the molecular-probe method -was suggested. A change in the optical properties of the aqueous solution of protein and of the cationic dye rhodamine 6G (R6G) upon exposure to the microwave field in the region of wavelengths of about 3 cm was revealed. In the works cited, these effects are attributed to several possible reasons: a change in the probability of proton transfer along the hydrogen bond, ionic and orientation defects of the water structure, and the appearance of long-lived metastable states under the influence of electromagnetic waves. However, all these are at the level of assumptions and unchecked theories, which is due, in our opinion, to the insufficient experimental base in this area.The aim of the present work is to investigate the influence of microwave radiation of two different frequency ranges -millimeter and decimeter ones -on the effectiveness of the association processes of the dye molecules dissolved in water.Experimental. The absorption spectra were measured on an automated Lambda-35 (Perkin Elmer) spectrophotometer. The error of measurements of the optical density was 0.0005 rel. units. The object of investigation was the dye R6G. Bidistilled water was used for preparing solutions. The concentration of R6G was 3⋅10 −4 mole/liter. The treatment of aqueous solutions was made with the aid of a "Khronos" electromagnetic activator. Irradiation was effected at two wavelengths: 2.0 mm and 6.9 dm. The time of irradiation varied from 10 to 60 min. Irradiation...

Application of Temperature-Dependent Fluorescent Dyes to the Measurement of Millimeter Wave Absorption in Water Applied to Biomedical Experiments

“…It is assumed [ 7 , 8 ] that millimeter wave irradiation of dyes solutions has possible additional nonthermal effect of millimeter waves on the spectral properties of solutions which is due to the change in the structure of water. During irradiation, pseudo polymer hydrogen bonding network undergoes deformation, rearrangement, and perhaps destruction.…”

Специфічна Дія Мікрохвиль На Водний Розчин Родаміну 6G За Даними Флуоресцентного Аналізу

“…On the other hand, the efficiency of association processes of R6G molecules depends on the parameters of the supramolecular (cluster) structure of water [15,27,28]. By assuming that microwaves destroy or deform the percolation cluster, one may expect that the effective distance between fluorophore moleculesthe parameters in the Arrhenius formula depend on it -should enlarge.…”