The responses of quartz crystal microbalance (QCM) sensors coated by fullerene and fullerene-aluminum films to ethanol and water vapors are investigated. The possibility of controlling the adsorption properties of such films by inserting the aluminum and by ultraviolet irradiation that changes the film morphology in a definite way is demonstrated.
Abstract. Color mixing models to obtain white light with a predetermined values of correlated color temperature and brightness are presented. One model describes mathematical algorithm for combination of spectra for WW LEDs lighting systems, and other one for systems based on RGBW LEDs. Results of testing of created sample of LED light source for indoor lighting ("Amstrong" type) with implemention of presented color mixing models are shown.
Last decades the enhancement of optical transitions near metal surface was observed under study the optical processes (luminescence, Raman scattering, IR absorption). The effect consists in an essential increase of the intensity of transition (for example, an effective cross-section increases by factor 10 5 …10 11 for Raman scattering and 10…10 4 for IR absorption) or efficiency of the processes near metal surface (e.g. generation of second harmonic). We have analyzed a various experimental techniques that made it possible to achieve an enhancement in surface enhanced infrared absorption (SEIRA), surface enhanced Raman scattering (SERS), metal-enhanced fluorescence. Under the conditions of our experiment and according to literature data, there was observed enhancement factor which equal to 3…20 for vibrations of various molecular groups in SEIRA. Peculiarity of another optical amplifier, namely, colloidal gold nanoparticles, which were effectively used for enhancement of signal in IR absorption and Raman scattering, metal-enhanced fluorescence, has been studied also. Different roughness of gold surface leads to changes in an enhancement factor. The structural features of bovine serum albumine (BSA)-colloidal gold system and enhancement of guanine that obtained in SEIRA experiment are discussed. Atom force microscopy (AFM) technique was applied to test the roughness of the metal surface. We made an attempt to model the factor of enhancement of electrical field and its frequency dependence for different metal surfaces, and ascertained that silver, gold and copper are the best.
This review is aimed at analysis of the system of discrete and continuously distributed boundary electron states (BES) on (111) and (100) silicon surfaces in the Si-SiO 2 structures prepared mainly using thermal oxidation of silicon. Used here are literature data as well as results obtained by authors when studying the temperature and electric field dependencies of the capacitive photovoltage. It has been ascertained that the BES system consists of a continuous U-like distribution in the silicon forbidden gap and from the discrete BES as well. There developed are two discrete BES in the thermally oxidized Si(111)-SiO 2 structure, while in the Si(100)-SiO 2 structure-four ones. These results well coordinated with ESR investigations were obtained using the method of temperature dependencies for capacitive photovoltage without application of an external electric field. As shown, application of various electric-field methods enables to determine only effective parameters of discrete and especially continuously distributed BES, which depend on the temperature of measurements, silicon resistivity and conditions of preparation of the Si-SiO 2 boundary. Considered are the features of preoxidation treatment of the silicon surface and its oxidation, the character of the intermediate layer between Si and SiO 2 , and the influence of such external factors as annealing in various ambient atmospheres, irradiation and high electric fields as well.
Abstract. Fine-dispersed ZnS doped with Cu was prepared using self-propagating hightemperature synthesis. In the photoluminescence excitation spectra, the blue shift of the host lattice excitation peak is observed for powder ZnS:Cu that contains nano-and mesosized (submicron) particles. The obtained spectra indicate that radiative recombination in meso-sized particles is significantly reduced as compared to micro-sized particles, which can be caused by the increase of non-radiative relaxation processes in surface states.
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