Fluorescent organic dyes solutions are used for non-contact measurement of the millimeter wave absorption in liquids simulating biological tissue. There is still not any certain idea of the physical mechanism describing this process despite the widespread technology of microwave radiation in the food industry, biotechnology and medicine. For creating adequate physical model one requires an accurate command of knowledge concerning to the relation between millimeter waves and irradiated object. There were three H-bonded liquids selected as the samples with different coefficients of absorption in the millimeter range like water (strong absorption), glycerol (medium absorption) and ethylene glycol (light absorption). The measurements showed that the greatest response to the action of microwaves occurs for glycerol solutions: R6G (building-up luminescence) and RC (fading luminescence). For aqueous solutions the signal is lower due to lower quantum efficiency of luminescence, and for ethylene glycol — due to the low absorption of microwaves. In the area of exposure a local increase of temperature was estimated. For aqueous solutions of both dyes the maximum temperature increase is about 7° C caused with millimeter waves absorption, which coincides with the direct radio physical measurements and confirmed by theoretical calculations. However, for glycerol solution R6G temperature equivalent for building-up luminescence is around 9° C, and for the solution of ethylene glycol it’s about 15°. It is assumed the possibility of non-thermal effect of microwaves on the different processes and substances. The application of this non-contact temperature sensing is a simple and novel method to detect temperature change in small biological objects.
1/ ƒ fluctuations are widely observed in various physical, chemical and biomedical systems. T.Musha and G.Borbely
took a laser light scattering experiments where 1/ƒ fluctuations directly represent the phonon energy fluctuations. Light
scattering experiments for liquids shows that scatterers are not propagating ones such as phonons, but localized ones.
Previously it was shown that hydrogen-bonded (H-bonded) liquids have structural heterogeneities of nanometer size
(supramolecular ones) which can act as localized scatterers of a light beam. In this work fluctuations of light scattering in
H-bonded liquids have been investigated. Power spectral density are describing by law S( f )~1/ƒ<sup>α</sup> where index
α depends on the type of liquid and molar ratio water/glycerol in solution. Two simple models which can explain this
phenomenon are considered. The first model is a one-dimensional chain with nonlinear interaction between atoms,
known as the Fermi-Pasta-Ulam system. In such a system there is a transfer of energy among modes, resulting in slow
1/ƒ fluctuations of total energy. In the second model we consider liquids structure by percolation theory which predicts
an existence of weak supramolecular heterogeneities. Thus, intensity fluctuations might reflect fluctuations of the cross
section scattering centers and/or fluctuations in the number of such centers in the volume of scattering.
The structure of associated liquids is proposed to be described in terms of the fractal conception developed for
amorphous media. The low-frequency region of Raman scattering spectrum for such liquids is shown to reflect fractal
features of these media. Binary H-bonded solutions are taken to gain controlled modifications of the fractal parameters
and at the same time to avoid dealing with a number of unknown variables. In particular the glycerol-water fractal
parameter at certain concentration reflects the competition between different H-bond networks. This concentration
corresponds to the density anomaly 40% concentration.