Carbon dots have been modified using UV irradiation (405 nm laser light). UV irradiation of carbon dots has led to various changes in optical properties, which in turn means photomodification of the carbon dots surface. With an increase in light transmission, we have obtained the increasing intensity of photoluminescence and a blue shift by the laser irradiation of the carbon dots. The proposed method can help to adapt and improve the optical properties of carbon dots and can be used in applications, for example, in the optical encryption field.

The plasmon enhancement of carbon dots (CDs) photoluminescence (PL) in thin-film structures with metal nanoparticles is of interest in their practical applications in sensors and light-emitters. This paper investigates CDs in the thin-film structures with nanogranulated silver films with different thickness. CDs in an aqueous solution were precipitated by spin-coating over the surface of annealed Ag films coated previously by a polymer layer. The IR, optical density and PL spectra of free-CDs and in thin-film structures with Ag films were studied. The PL intensity enhancement of CDs was demonstrated in the thin-film structures with Ag films due to absorption cross-section enhancement and the action of the Purcell effect. The improvement of thin-film structures producing technology will contribute to PL enhancement of CDs and the development of new thin-film sensors, light-emitters and other devices on their base.

In this paper, we studied the properties of a multifunctional system, in which the luminescent and magnetic properties are combined. The calcium carbonate microspheres are used as porous matrices for complexes combining luminescence properties of AgInS2/ZnS quantum dots and magnetic properties of Fe3O4 nanoparticles. The study investigates the effect of magnetic nanoparticles concentration on optical properties of quantum dots in CaCO3-Fe3O4@AgInS2/ZnS complexes. It is shown that applying calcium carbonate microspheres as a matrix permits to reduce quenching of the quantum dots luminescence. Keywords: hybrid system; ternary quantum dots, magnetic nanoparticles, iron oxide; calcium carbonate microspheres.

Subject of research. This paper focuses on the study of temperature effect on the threshold intensity values for fluorescent mark recording as well as on the features and threshold intensity values for photosensitive material damage during nonlinear phototransformation of chromone derivatives by visible light. Method. Photosensitive chromone derivative compound embedded into polymethyl methacrylate (PMMA) polymer films with 20 μm thickness on the glass substrate were used as samples. Fluorescent marks were recorded by diode pumped passively Q-switched microchip Nd:YAG laser with the second harmonic generation. The wavelength of recording laser pulse was 532 nm, pulse duration was equal to 1 ns. Sample temperature was controlled by Peltier element and was changed in the range of 0–100 °C. Recorded fluorescent marks were registered using confocal laser scanning microscope. Main results. It was shown that cooling of the sample from 25 °C to 0 leads to decreasing of laser induced damage of the sample. Heating of the sample from 25 °C to 100 leads to the decreasing of the threshold intensity for nonlinear recording of fluorescent mark and corresponding efficiency increase of photoinduced transformation process at the fixed energy and duration of laser pulse. Practical relevance. Requirements for thermal stabilization system in the device for nonlinear optical archive information recording can be specified based on acquired results.

Luminescent images of a few distinguishable alloyed semiconductor quantum dots obtained at room temperature using confocal scanning microscopy with spectral and temporal resolution demonstrate blinking of spatially distinguishable spots and local luminescence spectra varying within the ensemble.