Optics and Spectroscopy最新文献

The structure and electrical and optoelectronic properties of nanostructured carbon films obtained by methane plasma deposition with subsequent annealing have been studied. It is shown that the film formation conditions affect the final physicochemical parameters. The film morphology has been investigated by atomic force microscopy, scanning electron microscopy, Raman spectroscopy, X-ray energy-dispersive analysis, and analysis of the current–voltage characteristics (CVCs). The film thicknesses range from 20 to 150 nm at the carbon-to-oxygen (C/O) atomic ratio of 4 : 1. Structural studies show that the films obtained consist of nanographite flakes with the lateral dimensions in the range from 5 to 12 nm and contain different fractional concentrations of sp³/sp² crystalline phases of carbon. It is established that the structural quality of carbon films decreases with an increase in the annealing temperature from 650°C to 800°C. At the same time, the degree of graphitization increases, which is indicated by Raman spectroscopy data and sheet resistances calculated from the CVCs. Photocurrents are calculated from the temperature dependences of the CVCs; it is found that the samples exhibit photosensitivity in the temperature range from room temperature to –173°C. These results may be useful for designing day and night light sensors and temperature sensors operating in a wide temperature range.

The defect of the angular momentum of an electron under cyclotron (synchrotron) radiation, including in terms of its spatial orientation, as well as the spatial orientation of the emitted photon, is considered. The possibility of the compatibility of the idea of the photon as a gauge boson, which can exist only in two spin states, ±1, with a linearly polarized photon, i.e., having no spin, has been studied. It is established that photons have no spin. The angular momentum defect can carry away a spinless photon. As applied to the angular momentum defect, the photon momentum arm is equal to its reduced wavelength.

The two-photon interference appearing in a mental experiment similar to the Young’s experiment as a result of simultaneious emission of two photons by (two) independent point sources under the assumption that their radiation is described in the electric-dipole approximation in the classical electrodynamics is simulated within the framework of the photon quantum mechanics by using a six-component photon wave function in the coordinate representation and, for comparison, in the proposed “quasi-classical” approach by using the one-component photon wave function. The relevance of introduction of the photon wave function is emphasized in comparison to the concept of the photon being a “train” of real electromagnetic waves. The task of setting up new experiments that could initiate the analysis of the physical nature of quantum phenomena that occur in the physical vacuum and are formally described by the wave function in the quantum mechanics or by transition amplitudes in the quantum electrodynamics is proposed.

A quantitative analysis technique has been developed, based on multiple regression of Fe–Cr–Mn–Mo–N–C composite steels reinforced with oxide and nitride particles using a BRA-135F spectrometer, to determine the concentrations of chromium, manganese, molybdenum, aluminum, and iron. The problem of the selection of peaks for the analysis at a total content of chromium (11.50–15.03 wt %), manganese (7.56–12.18 wt %), and iron (66.54–74.08 wt %) is considered. Optimal lines of the spectra of the steels under study are proposed to obtain satisfactory results in qualitative analysis with account for the peak overlap. It is shown that due to the overlap of the peaks, chromium should be determined by the peak relating to the CrK_α line; manganese, by the peak relating to the MnK_α line; and iron, by the peak relating to the FeK_β line. An approach to selecting peaks to determine molybdenum concentrations is described. It has been found that due to the absence of a reliable separation of the peaks relating to the MoK_β1 and MoK_β2.5 lines, the molybdenum content should be determined by the peak relating to the line MoK_α. The ingots used as calibration samples were preliminary chemically analyzed to determine the content of metals on an atomic emission spectrometer with the inductively coupled plasma Spectroflame Modula S, which provides high stability and reproducibility of the analysis results in a wide concentration range of elements, including those with a low limit of d-etection. The analysis for determining the concentrations of nitrogen and oxygen in the calibration samples was performed using a METAVAK-VAK analyzer, and the carbon content was determined on a METAVAK CS-30 analyzer.

The extraordinary phase transition in antiferromagnetic thin films has been analyzed by computer simulation. The simulation has been performed using the Ising model and the Metropolis algorithm. Epitaxial films with a cubic lattice containing several monoatomic layers have been considered. The condition for the occurrence of surface and extraordinary phase transitions is the difference between the exchange integrals in the bulk of the film and on its surface. It is shown that the surface and extraordinary phase transitions occur in antiferromagnetic thin films containing no less than eight monoatomic layers. The extraordinary phase transition has been investigated for different film thicknesses. It is shown that the magnetic susceptibility near the phase transition line has a logarithmic dependence on the phase-transition temperature. The dependence of the critical indices of the logarithmic phase on the film thickness is obtained.

All naturally found and man-made solid microparticles have a rough surface. Upon optical radiation scattering from such particles, in addition to geometric shape, the surface texture becomes an important morphological factor of the scatterer that determines its optical properties. We present the results of numerical FDTD simulation of an optical-wave focusing by a dielectric microsphere with a randomly distributed surface roughness. The cases of azimuthally symmetric and asymmetric distortions of the particle surface are analyzed. It is demonstrated that the key parameters of the near-field focal region (intensity, longitudinal and transverse dimensions, focal distance) referred to as the photonic nanojet (PNJ) turn out to be sensitive to changes in the sphere-surface texture. In the process, two parameters, the peak intensity of the PNJ and its length, experience the largest changes. The influence of the optical contrast (the relative refractive index) of the microsphere that scatters radiation on PNJ characteristics is analyzed, and the possibility of reducing the influence of surface roughness on the quality of the near-field focusing by means of microsphere watering (water-uptake) is demonstrated.

The paper has shown the possibility of a comprehensive quantum chemical study of the molecular structure and energies of the excited states of the mesogenic europium(III) binuclear complexes with substituted β-diketones and Lewis bases. The interrelationships between the geometric parameters of complex molecules and the structural features of coordination polyhedra and the probability of their manifestation of liquid crystalline properties have been studied. The structural features of the first coordination sphere of binuclear complexes have been considered and the calculated parameters of Voronoi–Dirichlet polyhedra have been compared with the data for the mononuclear complexes. On the basis of the results of the calculations of the lowest singlet and triplet excited states, the diagrams of energy levels have been constructed, the main channels of intramolecular excitation energy transfer have been determined, and the luminescence efficiency of compounds luminescence efficiency has been evaluated.

The focusing of laser radiation with triangular dielectric prisms has been numerically studied using the finite element method implemented in the COMSOL Multiphysics software package. It has been shown that two-dimensional triangular prisms make it possible to focus light in free space into spots smaller than the scalar diffraction limit. For example, a quartz glass prism with a base width of 60 μm and a height of 28.5 μm illuminated by light with a wavelength of 4 μm produces a photonic nanojet with the maximum intensity that exceeds the incident radiation intensity by a factor of 6 and has a full width at half maximum of 0.38 of the focused radiation wavelength. The focal spot size can be decreased by selecting the height of the prism so as to the maximum intensity was located inside it. In particular, a barium titanate prism with a height of 21 μm and a base width of 60 μm forms a focal spot directly behind its apex with a width at half maximum equal to 0.25 of the focused radiation wavelength. It has been shown that the use of a prism weakens the wavelength dependence of the focal spot width as compared with the case of a microcylinder. In particular, for a quartz glass microcylinder 60 μm in diameter, a change in the wavelength from 3 to 5 μm leads to the spot width variation by 0.09 of the focused radiation wavelength, while for a prism, by 0.05 of the focused radiation wavelength on average.

In this paper we report on results of an investigation of a transparent mesh electrode in a wide wavelength range 550–2000 nm with low electrical resistance manufactured by laser ablation with using an aluminum film with a thickness of 30 pm on a polyimide substrate with a thickness of 20 μm. The method is implemented using a fiber ytterbium nanosecond laser with a wavelength of radiation 1064 nm. The structure we have obtained has a transmittance >50% in the designated spectrum range and the electrical resistance <1.5 Ω/sq.

The method of static (non-flow) spectral digital microscopy (SSDM) method to identify, to count and to determine the standard and individual characteristics of native blood erythrocytes is suggested. The object to study was the whole donor blood diluted by saline and placed into the counting Goryaev camber. Among the standard characteristics of erythrocytes, the following were determined: the concentration of erythrocytes in a blood sample RBC (Red Blood Cells concentration), the scatter of erythrocytes by volume RDW (Red cells Distribution Width), including RDW-SD and RDW-CV, hematocrit HCT, mean erythrocyte volume MCV (Mean Cell Volume). n addition, the possibility of measuring the average hemoglobin content in erythrocyte MCH (Mean Cell Hemoglobin), MCHC (Mean Corpuscular Hemoglobin Concentration), as well as the total content of hemoglobin HGB in the blood sample (Hemoglobin) was investigated. The peculiarity of SSCM method proposed lies in the fact that it fundamentally allows to determine not only the general hematological characteristics of blood samples (RBC, RDW-SD and RDW-CV, HGB), but also the mean values of the characteristics of native blood erythrocytes (MCV, MCH, MCHC), and also, and most importantly, the individual characteristics of each erythrocyte. The latter permitted the authors to introduce a new type of erythrocyte characteristics ICV, ICH, ICHC (Individual Cell Volume, Individual Cell Hemoglobin, Individual Corpuscular Hemoglobin Concentration). In turn, this made it possible to obtain the histograms of hemoglobin distribution in erythrocytes of a blood sample along with the traditional distribution of their volumes, which can serve as an additional tool in the field of hemodiagnostics. Thus, the paper shows that SSCM method makes it possible to compile an individual metrological “passport” for each erythrocyte of the blood sample under study—this is the main feature of this work.