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Русинов А.П.
Rusinov A.P., Kucherenko M.G.
HOLOGRAPHIC REGISTRATION METHOD OF NONRADIATIVE DEACTIVATION EXCITED STATE MOLECULES IN POLYMER FILM. INFLUENCE OF METAL NANOPARTICLES
When interacting condensed matter systems with electromagnetic field it is necessary to consider the processes of nonradiative decay of electronic excitation energy of molecules. However, existing registration methods of nonradiative processes are related to methodological errors and low sensitivity measurements. In this paper, we proposed a method of improving measurement sensitivity of thermal field generated by nonradiative deactivation excited state molecules, through the use of holographic methods. In this case the temperature field initiated by spatially periodic field of pump pulse generated the holographic phase grating. Therefore diffraction signal of probe beam on single grating period increased as square of structure periods number. Some limitation of this method is relatively fast thermal relaxation of the lattice. However, in some mechanism of grid recording this limitation becomes irrelevant. So in polymer films under impact of intense radiation pumping on the polymer surface is recorded relief grating, the depth of which is proportional to temperature in polymer volume. In this case, the lifetime of relief structure is several orders of magnitude larger than thermal grating, which greatly simplifies the experimental registration of surface relief dynamics. This technique allows to experimentally measuring the nonradiative transitions efficiency depending on sample microstructure or environmental conditions. For approbation this method influence of silver nanoparticles on nonradiative transitions in polymer films is studied. It is shown that adding nanoparticles increased the amplitude of relief gratings reordered on the film surface by swelling mechanism, indicating the intensification of nonradiative deactivation processes of electronic excitation energy of dye molecules. It is found that the influence of silver nanoparticles on nonradiative processes for molecules with low quantum yield in metastable (triplet) state (rhodamine 6G) is much higher than for molecules with a large quantum yield in this state (erythrosine).
Key words: nonradiative transitions, holographic method, laser swelling of polymer, relief-phase grating, silver nanoparticle.
Rusinov A.P., Kucherenko M.G.
INFLUENCE OF SILVER NANOPARTICLES ON THE OPTICAL ABSORPTION SPECTRA OF ORGANIC DYES MOLECULES IN POLYMER SOLUTIONS AND MEMBRANES
Objects and systems structured at the nanometer scale are of great interest among researchers due to the presence of their specific physical properties. Due to considerable experimental difficulties and limitations of theoretical approaches, the focus now is on study of relatively simple nano-objects for which there are suitable experimental methods, known methods of synthesis and physical models for theoretical description of their properties. As an example of such a system is considered colloidal solutions of metal nanoparticles and nanoparticles in polymer film. Influence of metal nanoparticles on molecular environment due to the presence of plasmon oscillations of electron gas density. This changes the interaction efficiency between nearby molecules with external electromagnetic field and the rate of photoinduced processes in this area. The influence of various concentrations of silver nanoparticles on absorption spectra of organic dyes molecules in water solutions and thin polyvinyl alcohol films is investigated. It is found that with increasing concentration of metal nanoparticles optical density of polymer solutions and films in the 380–450 nm band increases monotonically, as in the 490–570 nm band increases at low nanoparticles concentrations and decreases at higher nanoparticles concentrations. Maximum enhancement of the dye absorption is observed when at concentration nanoparticles near 10-9 M. Based on the model of influence metal nanoparticles on interaction of organic dye molecules with linearly polarized monochromatic electromagnetic field spatial orientation and frequency dependence of transition probabilities in dye molecule within nanoparticles is calculated. It is shown a qualitative agreement between the theoretical frequency dependences with the experimental results of concentration effect of silver nanoparticles on the absorption intensity of dye molecules in different spectral ranges.
Key words: silver nanoparticle, organic dye, absorption spectrum, induced transitions.
Rusinov A.P., Kucherenko M.G., Fedorov D.S.
HOLOGRAPHIC RECORDING OF THE RELIEF-PHASE GRATINGS IN POLYMERIC MEDIA BY THE LASER SWELLING MECHANISM
The process of laser initiation of relief structures on the films surface of polyvinyl alcohol (PVA) by the laser swelling mechanism. Laser action was selected in which ablation of the polymer excluded. The simple mathematical model of the recording of the relief-phase gratings by the laser swelling mechanism was proposed and the calculations which made on the basis of a theoretical model were compared to experimental data.
Key words: laser swelling, relief-phase grating, diffractive efficiency, viscoelasticity.
2006,
Kucherenko M.G., Rusinov A.P.
DIFFRACTION OF PROBING BEAM ON TRANSITIONAL HEAT STRUCTURES IN SYSTEMS WITH SATURABLE THREE - LEVELS CENTERS.
Analysis of the process of optical record and disintegration of transitional space structures in the system with nonlinear response, stipulated for incoherent saturation of three - level center is made. The main attention is paid to heat mechanism of phase record in spheres with coefficient of heat conduction, which doesn't depend on the temperature. Relaxation of heterogeneous temperature field and diffraction of probing beam on transitional structure is researched.
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Editor-in-chief |
Sergey Aleksandrovich
MIROSHNIKOV |
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