Optics and Spectroscopy最新文献

The methods of absorption electronic and NMR spectroscopy were used to study the processes of complexation during the interaction of molecules of unsubstituted indoline spiropyran with aluminum salts. The mechanism of formation and structure of complexes of two types has been established. Negative photochromism of the complex of the merocyanine form of spiropyran with aluminum ions was found. The stability of metal complexes to the action of various agents has been investigated.

The review is devoted to the principles, state of the art and problems of diffractive optics used to focus X-ray and γ-radiation in telescopes at orbital stations. Various multilayer structures for normal incidence telescopes, supermirrors for Wolter optics, Laue lens as a soft γ-radiation concentrator, as well as modified Fresnel zone plates for focusing radiation in a wide energy range with an unprecedented high angular resolution (10^–1–10^–3″).

In this work, we study the nonlinear absorption of ultrashort laser pulses of variable duration (0.3‒10 ps) in a bulk polycrystalline ZnSe dielectric. The transmission of the sample was measured for two wavelengths, 515 and 1030 nm, in a wide range of intensities. A nonlinear behavior of the transmission is found when the sample is irradiated with laser radiation at a wavelength of 515 nm with absorption saturation in the region of 3–5 TW/cm². Surface damage thresholds were obtained for a wavelength of 1030 nm for pulse durations of 0.3–10 ps.

Influence of light exposure duration (model 18 : 6) on hormonal indices of stress-implementing system in laboratory animals blood is studied. Activity of stress systems central link was evaluated based on data on concentration of adrenocorticotrophic hormone, melatonin and β-endorphin in blood serum, observed during enzyme immunoassay. Reaction of peripheric link of the stress-implementing system was evaluated in blood smears based on results of qualitative count of catecholamine granules in erythrocytes. It was established, that variations of hormonal indices of the stress systems for laboratory animals depend on trigger factor activity periods. With increase of the experiment duration to 21st days the most pronounced reduction of melatonin, β-endorphin and increase of adrenocorticotrophic hormone concentration, as well as sharp increase of catecholamines level are observed in the blood serum. These hormonal changes develop as a result of failure of compensation mechanisms of the stress-implementing systems in connection with melatonin rhythms disturbance, that indicates the gradual development of the general adaptation syndrome.

The luminescence excitation energy transfer in europium and terbium indole-3-carboxylates, indole-3-acetates and indole-3-propionates as well as ternary indolecarboxylates containing 1,10-phenanthroline and 2,2'-bipyridine molecules have been studied. The luminescence excitation spectra, the lifetimes of the ⁵D₀ (Eu³⁺) and ⁵D₄ (Tb³⁺) states, and the luminescence intensity are analyzed. The decisive role of ligand-metal charge transfer (LMCT) states in the quenching of the luminescence of europium aromatic carboxylates containing a π-excessive pyrrole or indole fragment is demonstrated. Most europium compounds are characterized by quenching due to the depopulation of the ⁵D₀ state of the Eu³⁺ ion through the low-energy LMCT state. But in some ternary compounds, the LMCT state being of higher energy participates in the nonradiative depopulation of the excited electronic states of the ligand.

A study of high-NA focusing process of ultrashort laser pulses in bulk of ZnSe has been carried out. It is shown that when focusing laser Gaussian beam with high-aperture lenses into a transparent medium aberration distortions occur leading to an increase in focal spot size. The results of experimental studies on ablation of front and back surfaces of a plane-parallel plate with 4 mm thickness made of ZnSe by laser pulses with a duration of 0.3, 1, 10 ps and a wavelength of 1030 nm focused by a micro lens (NA = 0.55) are presented. It is shown that at low pulse energies focusing can be considered in a linear mode in which focal spot size is due to aberration distortions.

An efficient pulsed gas-discharge inductive CO₂-laser with a radiation energy of 1.05 J has been developed for the first time. In this case, the pulse duration of the laser radiation was about 10 ms. The maximum efficiency of 21.1% was obtained at a radiation energy of 340 mJ. HF current pulses propagated along the inductor conductor and, thus, an inductive discharge was formed to create a population inversion at the infrared (IR) transitions of CO(_{2}^{*}) molecules. The temporal and energy characteristics of the radiation of the inductive CO₂-laser depending on the duration of the pump pulse are investigated. The spatial characteristics and spectrum of the radiation of the developed laser are estimated. The divergence of the laser radiation was 0.52 mrad. The cross-sectional dimension of the laser output beam was about 35 mm in diameter.

Crystals of the concentration series ZrO₂–(8–10) mol % Sc₂O₃–(1–2) mol % Tb₂O₃ were grown by the method of directional crystallization of the melt from a cold container. Analysis of the spectral-luminescence characteristics of these crystals after growth and after annealing processing in a vacuum revealed the presence of both Tb³⁺ and Tb⁴⁺ ions in them. In crystals ZrO₂–(8–10) mol % Sc₂O₃–(1–2) mol % Tb₂O₃, the presence of a process of non-radiative energy transfer from Tb⁴⁺ ions to Tb³⁺ ions was revealed.

A formula for calculating the relativistic electron localization function (RELF) within the framework of the Dirac–Fock method is obtained. An approach similar to that used earlier in [A.D. Becke and K.E. Edgecombe, The Journal of Chemical Physics 92, 5397 (1990)] in deriving an expression for the nonrelativistic electron localization function (ELF) is applied. It is demonstrated that the expression for RELF differs from the expression for ELF with replacement of the nonrelativistic electron density by its relativistic counterpart. Relativistic calculations of ELF and RELF for a number of superheavy elements are performed and the results are compared. By several examples it is shown that the ELF value equal to 0.5 does not necessarily correspond to the distribution density of homogeneous electron gas.

Using the method of dynamic light scattering, it was found that the rate of collagen cleavage under the influence of bacterial collagenase decreases by almost 4 times when protein molecules are doped with Cr³⁺ ions, and when the enzyme activator of Zn²⁺ ions is added, it increases by 1.3 times. Based on the experimental data, the reaction rate constants k₁ were calculated. It was found that when collagen molecules are tanned with a chromium salt, it becomes more resistant to degradation in solutions containing zinc ions than in solutions with the addition of calcium ions, as we described in earlier works.