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951.
Theoretical analysis of the spatial, noise, and energy characteristics of an amplifier has been performed in the mode of spectral and time selection using subnanosecond stimulated Raman Scattering gain of weak echo signals in crystalline active media that are known for high (up to 10–1 cm/MW) gain coefficients. The possibility to reach high gain values has been demonstrated for weak signals from objects at acceptable angular sizes of the field of vision of an amplifier. To provide a signal-to-noise ratio that exceeds unity over the entire field of vision, the number of photons at the input to an amplifier that is required has to exceed the number of its resolution elements. Accurate determination of the possibilities of recording of weak echo signals and quality of images of targets that are obtained using amplifiers under stimulated Raman Scattering requires additional special experiments. 相似文献
952.
We have investigated the laser-excited photoluminescence spectra of powder and aqueous solution threonine. The spectral ranges of the photoluminescence and its intensity maxima have been determined. We have measured the spectral dependence of the molar extinction coefficient of an aqueous solution of threonine. Using quantum-chemical methods, we have calculated the electron absorption spectrum, the dipole moment, and the distributions of charges on individual atoms of the threonine molecule. The calculated electron absorption spectrum has been compared with experiment. 相似文献
953.
S. V. Bashkin A. O. Karfidov V. N. Kornienko M. V. Lel’kov A. I. Mironov A. N. Morozov S. I. Svetlichnyi S. E. Tabalin I. L. Fufurin 《Optics and Spectroscopy》2016,121(3):449-454
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. 相似文献
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E. Santoyo R. García R. Abella A. Aparicio S. P. Verma 《Journal of chromatography. A》2001,920(1-2):325-332
A new application of capillary electrophoresis for measuring major and trace anions in thermal water and condensed-steam samples is presented. Ten fluid samples were collected from hydrothermal springs and fumaroles located in a volcanic zone of Deception Island, Antarctica. Anion separation was achieved in less than 6 min using indirect UV detection at 254 nm with a negative power supply (−15 kV). The electrolyte consisted of 4.7 mM sodium chromate, 4.0 mM electroosmotic flow modifier (OFM) hydroxide, 10 mM 2-(N-cyclohexylamino)ethanesulfonic acid and 0.1 mM calcium gluconate (pH 9.1). Major anions (Cl−, SO42, PO4H2−, and CO3H−) were measured using hydrostatic injection (10 cm for 30 s) at 25°C. Trace amounts of anions (F−, Br−, and NO3−) were better determined by electromigration injection (4 kV, 10 s) at 15°C. Good reproducibility of the migration times (<0.72% RSD), a satisfactory linear response and accuracy as well as acceptable detection limits were successfully obtained. 相似文献
960.
Maria I. Colombo Sebastián A. Testero Silvina C. Pellegrinet María L. Bohn Edmundo A. Rúveda 《The Chemical Educator》2001,6(6):350-352
A comprehensive laboratory experiment suitable for advanced undergraduate organic chemistry students has been designed. The experiment is based on the dienone-phenol rearrangement reaction of the sesquiterpene santonin to give -desmotroposantonin acetate. It challenges students to solve an earlier controversial stereochemical problem. The students carry out the reaction and analyze spectroscopic data to determine the stereochemistry of the starting material and the product. In addition, they perform simple molecular modeling calculations, which enable them to rationalize the stereochemical outcome of the transformation and discuss the mechanism of the dienone-phenol rearrangement and related rearrangements reported in the literature. 相似文献