Phototransformations of Phenols in Aqueous Solutions under Different Excitation Modes

The photolysis of aqueous solutions of two widespread environmental organic ecotoxicants—phenol and 4-chlorophenol—on excitation by UV radiation from a KrCl exciplex laser and a glow-discharge KrCl excilplex lamp was studied. The irradiated solutions were studied by spectroscopic techniques. The laser and lamp photolyses were compared.     

Theoretic and Experimental Study of Photoprocesses in Substituted 4-Dicyanomethylene-4H-pyrans

The photoprocesses in substituted 4-dicyanomethylene-4H-pyran (DCM) derivatives were studied theoretically and experimentally. The experimental spectral and luminescent parameters of the molecules under study are in good agreement with the results of quantum-chemical calculations. Trends changes in the spectral and luminescent properties depending on the molecular structure were established. The appearance of the S₂ level near the S₁ level in the scheme of the energy states of symmetrically substituted DCM (bis-DCM) causes changes in photophysical processes and a drop in the fluorescence quantum yield.     

An imaging Fourier transform spectroradiometer with a multi-element photodetector for the spectral range of 7–14 μm

The construction and principle of operation of a imaging Fourier transform infrared spectroradiometer (FTIR spectrometer) equipped with a cooled 32-area photodetector designed for spectral analysis of open atmospheric paths are considered. The main technical characteristics of the Fourier spectrometer are reported. The technique of visualization of the detected vapor cloud is described. The results of field experiments using the imaging FTIR spectrometer are shown. Based on these results, the dynamics of motion of the cloud of material has been investigated, its angular and linear velocities have been estimated, and data on propagation of the cloud of material and change in its angular sizes in air have been obtained. A technique for analyzing data provided by two FTIR spectrometers is given, based on which one can estimate the size of the cloud and the distance to it from each device. It is shown that the results of detection of the cloud of material by the imaging FTIR spectrometer can be used to predict the propagation of material under study in space.     

Effect of thermal aging on the mechanical characteristics of a composite of a polyimide with an organosilicon resin

The effect exerted by thermal aging in air at 350°C on the thermal and mechanical properties of composite films prepared on the basis of heat-resistant polyimide PM and non-film-forming polymethylphenylsiloxane (PMPS) was examined. The phase segregation of polymeric composites of various compositions and the thermal aging rate were evaluated.     

Peculiarities of Structure and Morphology of Copper-Cerium Nanopowders Produced by Laser Ablation

Russian Physics Journal - Copper-cerium nanopowders CuOx–CeO2 (mass ratio Cu:Ce = 6:100) are prepared by mixing the dispersions of the copper and cerium oxides produced by the method of pulse...     

Spectral and luminescent properties of sensitizers based on psoralen substitutes

Psoralens (furocoumarines) are photosensitizers of vegetative origin increasing the sensitivity of biological objects to near-ultraviolet radiation (UV-A, 320–400 nm). In the present work, the influence of substitution on the energy level diagram is considered for the first element of the series-psoralen. The absorption and fluorescence spectra are investigated with the use of an SM-2203 spectrofluorimeter, and theoretical calculations are carried out. In addition, the results obtained are compared with the calculated and experimental results of other authors. The employed method of intermediate neglect of differential overlap (INDO) yields such parameters as an oscillator force, nature and energy of the transition, positions of triplets and singlets, etc. The geometry is optimized by the semi-empirical PM3 method of the program Hyperchem 6.03. A comparison of the calculated results for the examined compounds demonstrates that after the substitution, the absorption spectra are shifted toward the red range. The lower excited singlet of the 21,22-dimethyl-10,11-cyclohexylpsoralen compound lies higher than that of psoralen and 10,11-phenyl-21,22-cyclohexylpsoralen; it is located at 332 nm. The absorption spectra from the excited states undergo a bathochromic shift after the substitution. The most intensive T-T absorption bands are also indicated in this work. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 7, pp. 43–49, July, 2008.     

Simultaneous pumping in atomic and ionic self-terminating transition laser

Solutions to the kinetic equations describing simultaneous pumping of working levels are obtained in quadratures for a laser operating on self-terminating transitions in the spectrum of an atom and an ion of the same element. The solutions reflect general features in the behavior of the population of resonance levels of the atom and ion depending on the electron concentration and make it possible to estimate the upper boundary of the energy parameters of lasing. By way of example, simultaneous pumping of working levels of the calcium atom and ion is considered. It is shown that the values of population of the levels, power, and energy of laser pulses of such an atomic-ionic laser are comparable. It is noted that the potentialities of ion lasers can be fully realized if appropriate conditions are created for level excitation during the propagation of the entire pump pulse (especially in its final phase).