Comparison and analysis of optical properties between vertical and inclined GaAs nanostructures

In this paper, COMSOL multi-physics field commercial software was used to design the simulation model of GaAs nanostructures array (vertical nanoholes, vertical nanowires, inclined nanoholes and inclined nanowires), and the changes of light absorption of these structures in the wavelength range of 200–840 nm were studied. The electric field distribution, carrier distribution and quantum efficiency of nanostructures are calculated and analyzed under certain structural parameters. The results show that the light absorption performance of nanowire structure in the short-wave region is better than that of the nanoholes structure. With a certain inclined angle, the inclined nanowire structure has a stronger light capture ability than the vertical nanowire structure, and the light absorption of nanowire structure has a minimum value at the 550 nm wavelength.

Mechanical, electronic and optical properties of bulk and monolayer GeSe2

[Formula: see text], a semiconductor with wide bandgap, has attracted wide attention due to its excellent workability in the short-wave region. Here, we reported the mechanical, electronic and optical properties of bulk and monolayer [Formula: see text] by using first-principles calculations. Our results show that both Young’s modulus and Poisson’s ratio of the monolayer [Formula: see text] exhibit anisotropic behaviors. From the bulk to the monolayer structure, the direct bandgap increases from 2.496 eV to 3.030 eV. Compared to the bulk structure, the monolayer [Formula: see text] exhibits the small average effective mass and significant anisotropy in optical absorption, indicating potential optoelectronic applications.

Квазимолекулярные оптические переходы вблизи резонансных линий атомов Kr и Xe в атмосфере гелия

A theoretical study of spectral profiles near the Kr and Xe resonance lines of the 1,3P1–1S0 transitions produced in the atmosphere of helium under equilibrium conditions is performed. Potential energy curves for the excited states of the Kr(4p55s)+He and Xe(5p56s)+He quasimolecules are obtained in the framework of the consistent use of the effective Hamiltonian method and the pseudopotential method. For the ground state experimental data are used. Based on quasistatic approach the spectral profiles of the quasimolecular absorption and radiation in the short-wave region of the resonance lines are calculated by applying the potential energy curves obtained. The resulting profiles are compared with experimental ones.

Determination of citrat ions in drugs on molecular luminescence of rutine in complex with yttrium (III)

The development of methods for qualitative and quantitative analysis of drugs can guarantee their identity and quality. Drugs used in the form of salts of organic bases are often determined by the anionic part of these salts. Citrate ions are a part of many drugs in the form of citric acid, salts of alkaline and alkaline earth metals. The purpose of this study was to develop a method for the luminescent determination of citrate ions in dosage forms using a complex of yttrium (III) with rutine (Rut) as a luminescent probe. It has been experimentally established that citrate ions increase the luminescence intensity of the Y(III)–Rut complex. The spectral and luminescence characteristics of the complex was studied. The luminescence spectrum of the Y(III)–Rut complex has a maximum at λlum = 570 nm. The luminescence intensity of the Y(III)–Rut complex increases and the luminescence peak shifts to the short-wave region of the spectrum (λlum = 522 nm) in the presence of sodium citrate. The maximum effect is observed at a pH of 6.5–7.5. The dependencies of the luminescence intensity on the concentration of Y(III) and Rut for the Y(III)–Rut–Cit complex at the constant concentration of citrate ions (1·10-3 mol/l) were studied. It was established that the maximum luminescence intensity was observed at concentrations of Y(III) – 2·10-3 mol/l and Rut – 5·10-4 mol/l. The linear region of the dependence of the luminescence intensity of the complex on the concentrations of Y(III) and Rut is observed in the range of yttrium concentrations 0.3–2.0·10-3 mol/l and rutine 0.5–5.0·10-4 mol/l. The method of luminescent determination of citrate ions in dosage forms has been developed. The method is based on the use of rutine molecular luminescence in the multi-ligand complex Y(III)–Rut–Cit. The method of determination of citrate ions in dosage forms differs favorably from the existing absence of toxic reagents, expensive equipment, short-term analysis time, allows rapid screening of samples of drugs.

Method of obtaining and studying the optical properties of carbon quantum dots.

The proposed method of synthesis of CQDs on the basis of nanoporous carbon obtained from plant raw materials. It is established that in the short-wave region a band is registered, which is due to the exciton mechanism of recombination, whereas in the long-wavelength region it is related to the state of defects. The kinetics of PL extinction is not strictly exponential, which most likely indicates the distributed nature of fading from individual emitters.

Optimization of the observation of postpartum pyo-inflammatory diseases in patients after vacuum-aspiration using the method of fluorescent spectroscopy

The growth of the frequency of postpartum purulent-inflammatory diseases requires the development of new approaches to their early diagnosis and treatment. The purpose of the study is to choose the optimal time for manual vacuum aspiration in patients with postpartum endometritis and to control the state of patients after it, using the method of fluorescence spectroscopy. The results of treatment of 392 patients who were on inpatient treatment in the gynecological department №2 of the City Clinical Maternity Hospital №2 were analyzed. Of these, 120 patients were selected for the diagnosis of which, in addition to the standard algorithm, the method of fluorescence spectroscopy was included. Manual vacuum aspiration was performed in 96 cases (80,0%). In 15% of patients, after vacuum-aspiration of the uterine cavity, blood serum tests using the method of fluorescence spectroscopy were carried out in dynamics. In 92,8% of them, an increase in fluorescence intensity and a shift of lmax in the short-wave region was observed, which was a reliable sign of improving the condition of the patients. Thus, the improvement of the state of patients after vacuum aspiration was confirmed at the appropriate level, using the method of fluorescence spectroscopy, which is a reliable method of diagnostics of postpartum purulent-inflammatory diseases.

Search of new luminophores with predetermined physicochemical and chemical properties ХVІ. N-arylmethylene- and N–hetarylmethylene- substituted for polyvinylamine

Investigation of transformation of polyacrylamide (PAA) in the polyvinylamine (РVAm) the reaction of Hofmann and further transformation of NH2-groups polymer by the Leuckart—Wallach reaction. The reliability of the transformation of PAA into PVAm is confirmed by the reaction of diazotization and acylation of the samples obtained by PVA and by the color reactions of the PVAm transformation products. The structure of PVAm is also confirmed by data from IR spectroscopy and pH-metric titration. The product obtained is a vinylamine copolymer (up to 80%), acrylamide and acrylic acid. Syntheses of N-arylmethylene- and N-hetarylmethylene substituted PVAm, is carried out by the reduction alkylating of NH2-groups of РVAm by aromatic and heterocyclic aldehydes [5‑(4‑chlorophenyl)-2-(4-formylphenyl)oxazol-1,3, 5-(4-methoxyphenyl)-2-(4-formylphenyl)oxazol-1,3, 5‑(4‑methylphenyl)-2-(5-formylfuryl-2)oxazol-1,3, 5-(4-methoxyphenyl)-2-(5-formylfuryl-2)oxazol-1,3, 3,5-diphenyl-1-(4-formylphenyl)-2-pyrazoline, pyrene-3-aldehyde, possessing luminescence, in presence formic acid. The indicated derivatives of PVAm are got also by successive formation with NH2-groups of elementary links of grounds of Schiff and reduction of them NaBH4. The derivatives of PVAm containing N-arylmethylene and N‑hetarylmethylene groups [...–CH2−CH(NH−CH2−Ar) – ... and ... –CH2−CH(NH−CH2−Het) – ...), respectively], low-grade in water, nonpolar organic, partially soluble in polar solvents and readily soluble in acid solutions.The got standards of modified PVAm, containing elementary links of …–СН2−СН(NH−CH2−Ar)–… and ...–СН2−СН(NH−CH2−Het)–..., luminesce both in the hard state and in solutions. IR-specta (hard state) РVAm and modified foods is studied, spectrums of absorption and luminescence of N-arylmethylene- and N‑hetarylmethylene substituted for PVAm, (in solutions of the mixed solvent is ethyl acetate - formic acid). The fluorescence maxima of PVAm derivatives are shifted to the short-wave region in comparison with similar solutions for initial aldehydes due to the reduction of the chromophore chain through the replacement of the aldehyde group with methylene.

Scintillation materials based on solid solutions ZnSxSe1–x

Composite materials based on ZnSxSe1–x solid solutions are promising materials for gamma and X-ray detectors. However, influence of compositions and particle size on scintillation properties is unclear, which prevents their application. This paper reports on the complex study of microcrystalline ZnSxSe1–x powdered scintillations, prepared by solid phase synthesis from ZnS and ZnSe initial compounds. ZnSxSe1-x solid solutions were obtained in the range of x from 0.07 to 0.86 and in the following sizes: 200—250, 140—200, 140—80 µm, and less than 80 µm. X-ray diffractions of powder ZnSxSe1–x shows formation of a cubic lattice of sphalerite structure. ZnSxSe1–x powders demonstrate a presence of a luminescence band in the 590—615 nm regions, while an increase in sulfur concentration leads to a shift of the maximum intensity of X-ray induced luminescence to the short-wave region, which is associated with an increase of the band gap width. The best parameters of X-ray induced luminescence are obtained for the solid solution with 39 at.% of sulfur. The ZnS0,39Se0,61 solid solutions obtained under these conditions have an X-ray induced luminescence intensity that is 4 times higher than that of ZnSe(Al) single crystal and a relatively low level of afterglow. In ZnSxSe1–x solid solutions, increasing of particle size leads to shifts of the X-ray induced luminescence to the longwave region. The highest intensity of the X-ray induced luminescence corresponds to the ZnS0,39Se0,61 composition with the particle size of less than 80 µm. Also, ZnS0,39Se0,61 solid solutions, with particle size less than 80 microns, are more homogeneous in composition, which is why the process of solid phase reaction in them passes more efficiently. It is shown that the ZnSxSe1-x composite scintillators can be used as gamma and X-ray detectors. It has been established that the effectiveness of these materials depends on their composition. ZnS0,5Se0,5 and ZnS0,39Se0,61 composites demonstrate the best scintillation characteristics, with twice as high an efficiency as that of the «commercial» ZnSe(Al) composite.