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).