The results on intensity noise and repetition frequency stability measurements for a passively mode-locked Cr:ZnSe laser pumped by a thulium-doped fiber laser at a wavelength of 1.94 pm are presented. The stability parameters and intensity noise are compared for three different generation regimes of the Cr:ZnSe laser. The laser operated at a repetition rate of 129.5 MHz and a central wavelength of 2.45 pm.
Noise influence on characteristics of current, flowing through semiconductor superlattice of nanodevice with prospects of using in terahertz spectroscopy, is examined. It is demonstrated, that the limit voltage, at which the current oscillations start, slightly depends on noise intensity. Oscillation amplitude increases at some noise intensity values for case without magnetic field and in the presence of a tilted magnetic field. At the same time with increase of noise intensity at developed oscillations the basic frequency decreases, while higher harmonics amplitudes can significantly decrease.
The interaction of femtosecond laser pulses with the surface of silica glass has been studied. As a result of interference between the incident radiation and surface plasmon polaritons, the formation of self-organizing subwavelength periodic structures with a period of 250 nm was observed. The minimum pulse energy at which recording occurs without surface ablation has been revealed.
A spectral model of luminescence of the two-component exciton-activated semiconductor quantum dot (QD) layered plasmon composite nanoparticle (CNP) with a dielectric core and a conductive shell in an external magnetic field is constructed, taking into account the inhomogeneity of the quasi-stationary electric field generated by QD in the CNP region, outside the framework of the approximation of the dipole polarizability of the CNP. The tensor formalism of describing the characteristics of the field in each of the layers of the CNP, as well as outside the CNP, is used. It is established that with a change in the structure of the nanocomposite, the parameters of its core or shell layer, the spectral response of the system to external magnetic field action changes. It is shown that the special form of the response is associated with the characteristic magnetic properties of the nanoparticle components acquired (under the action of the field).
Recently ferroelectric properties have been found in hafnia-based nanosized films. Such films are of the utmost interest for development of a universal memory, which combines the advantages of random access memory and flash memory. The paper studies optical properties of hafnia-zirconium oxide films H-fxZryO2 and lanthanum-alloyed hafnia-zirconium oxide films La:HfxZryO2. Fluctuations of thickness in HfxZryO2 do not exceed 3.5%, fluctuations of thickness in La:HfxZryO2 films—3.2%. Optical properties are analyzed based on effective-medium theory. According to effective-medium theory data, HfxZryO2 films contain 46% HfO2, 54% ZrO2, La:HfxZryO2 films contain 47.5% HfO2, 52.4% ZrO2, 2.5% La2O3.
A comparative study of the spectral-luminescent and spectral-kinetic properties of 3,3′-diethyl-9-methylthiacarbocyanine (MTCC) and 3,3′-diethylthiacarbocyanine (TCC) and their complexes with cucurbit[8]uril in aqueous solution was carried out. Dimeric complexes of TCC with cucurbit [8] uril consist of trans-isomers and exhibit only delayed fluorescence while dimeric complexes of MTCC consist of cis-isomers and exhibit both delayed fluorescence and phosphorescence in water. The dimeric complexes of MTCC and TCC with cucurbit [8]uril participate in the electron phototransfer reaction where the dimeric complex of MTCC exhibits a greater ability to enter into photooxidation reactions.
The optical properties of nanocomposite particles consisting of silicon cores about 100 nm in size with smaller gold nanoparticles deposited on their surface have been studied. An increase in the absorption of light in the nearinfrared region of the spectrum for the obtained nanoparticles is observed in comparison with that for nanoparticles of pure silicon or gold. Experiments on measuring the temperature of aqueous suspensions showed significantly higher rates of photoheating of nanocomposite particles upon irradiation with laser radiation at a wavelength of 810 nm compared to the case of pure silicon nanoparticles. Calculations of the distribution of the electric field showed multiple increases in its strength near nanocomposite particles upon irradiation with light in the visible and near-infrared ranges and also made it possible to find the scattering and absorption contributions to the extinction spectra of nanoparticle suspensions. The observed enhanced photoheating of nanocomposite particles can be used for application in antibacterial treatment and cancer hyperthermia.
The ceramics based on cubic (Zr0.82–xHfxY0.17Eu0.01)O0.91 with different contents of hafnium were studied. In the work, the elemental composition of the samples was obtained, the cathodoluminescence (CL) spectra and decay kinetics of europium luminescence were studied. The researched showed increase in the content of hafnium doesn’t affect the position and number of observed bands in the luminescence spectrum. The electric dipole and magnetic dipole radiative transitions ratio was estimated for all samples. It’s demonstrated that a decrease in the local symmetry of the europium ion associated with an increase in the hafnium content. It’s shown the 5D0–1F1 transition Eu3+ decay time doesn’t depend on the hafnium content, but v-aries significantly in different regions of the sample, which can be attributed to the influence of grain bou-ndaries.
Formyl radicals, DCO, were produced in solid CO matrix and studied by EPR using gas deposition technique on a cold substrate at 4.2 K. The radical electron spin-lattice relaxation was measured to be anisotropic. The anisotropy was found to originate from the anisotropic orientational motion of the radical with the most intensive librations performed around a z axis corresponding to the smallest moment of inertia of the molecule. It was shown that, in solid CO, the libration motion of small molecules is modeled by considering a particle rotating in the orientational potential box. A suggestion was substantiated about the complicated nature of the orientational motion of HCO in the solid CO matrix including the intensive librations and slow tunneling rotation of the molecule around the z axis.
The kinetics of changing in optical transmittance of palladium (Pd) nanolayers (about 10 nm thick, deposited on object glass substrates by thermal evaporation in vacuum) in hydrogen flow (100% H2) in the temperature range of 300–335 K are studied. It is shown that the rate of changing of palladium optical transmittance at hydrogen flow rises linearly with increasing the temperature due to sorption of hydrogen by Pd layer. The rate of changing in optical transmittance of Pd layer during sorption and desorption of hydrogen is established to rise by about one order with increasing the temperature from 300 to 335 K. The curves describing the changing in optical transmittance of palladium nanolayer during hydrogen desorption have two distinct sections: linear and nonlinear. The linear section of the curve weakly depends on temperature, while the nonlinear section sharply rises with increasing the temperature. Such the changing of the rate in optical transmittance can be associated with phase transition from β- to α-phase during hydrogen desorption from palladium.
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