Increase in the laser pulse length of lasers operating on self-quenching transitions

The reasons limiting the time for maintaining population inversion in lasers operating on self-quenching transitions are investigated theoretically and experimentally. It is shown how the nature of the pumping of the upper laser level affects this property of the active medium in N₂ and N₂-Ar lasers.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 1, pp. 81–86, January, 1978.     

Study of the Characteristics of Elementary Processes in a Chain Hydrogen Burning Reaction in Oxygen

The characteristics of possible chain explosive hydrogen burning reactions in an oxidizing medium are calculated on the potential energy surface. Specifically, reactions H₂ + O₂ → H₂O + O, H₂ + O₂ → HO₂ + H, and H₂ + O₂ → OH + OH are considered. Special attention is devoted to the production of a pair of fast highly reactive OH radicals. Because of the high activation threshold, this reaction is often excluded from the known kinetic scheme of hydrogen burning. However, a spread in estimates of kinetic characteristics and a disagreement between theoretical predictions with experimental results suggest that the kinetic scheme should be refined.     

Improvement of Image Spatial Resolution in Optoacoustic Tomography with the Use of a Confocal Array

The spatial resolution and size of the sensitivity area of tomographic systems are estimated by calculating sensitivity maps and spatial resolution maps in the image plane of complex arrays. The relation between the size of areas of high sensitivity and high spatial resolution for real-time oriented tomographic systems with confocal arrays is studied. It is shown that arrays with toroidal geometry significantly improve the diagnostic capabilities of optoacoustic and laser-ultrasound structural analysis of biological objects, rocks, and composite materials.     

Structural analysis of xCsCl(1 − x)Ga2S3 glasses

Sulphide glasses doped with rare-earth ions have been demonstrated to be suitable for photonic applications such as optical amplifiers, up-converters and fiber lasers. The substitution of metal halides into the glass network has been shown to result glasses with desirable properties in terms of quantum efficiency and fiber manufacture [J.R. Hector, J. Wang, D. Brady, M. Kluth, D.W. Hewak, W.S. Brocklesby, D.N. Payne, Journal of Non-Crystalline Solids 239 (1998) 176]. To assist in the understanding of this improvement a structural analysis of glasses with a composition xCsCl(1 ? x)Ga₂S₃ has been undertaken in order to examine the nature of the gallium environment. Information collected by high energy X-ray diffraction and neutron diffraction have been analyzed to permit the identification of the structural units as Ga centered tetrahedra. The interconnection between the tetrahedra was found to be predominantly corner sharing.     

Determination of the hydrogen diffusion coefficient in transformer oil

The hydrogen diffusion coefficient in transformer oil is determined by optically monitoring the dynamics of the hydrogen bubble dissolution in pure degassed oil. The diffusion coefficient is found to be roughly two orders of magnitude smaller than those determined earlier. This result is of great importance for chromatographic analysis of gases dissolved in transformer oil, since it gives grounds to suspect that hydrogen is not so volatile as implicitly believed in a number of works. Accordingly, the reliability of diagnostic data for high-voltage oil-filled equipment improves.     

Electromagnetic-wave reflectivity of the surface of a cubic-ferrite plate

The electromagnetic-wave reflectivity of the surface of an insulating cubic-ferromagnet (ferrite) plate is calculated analytically and numerically with allowance for spin-wave damping. The frequency and magnetic-field dependences of the reflectivity are found at the orientational phase transition point and in the vicinity of this point for various values of the plate thickness. It is shown that the reflectivity exhibits anomalous behavior when the dynamic magnetic permeability becomes equal to the dielectric constant, as well as when dimensional resonances occur for electromagnetic or acoustic waves or ferromagnetic resonance takes place. At frequencies below the magnetoelastic gap in the quasi-spin-wave spectrum, the reflectivity may have anomalously low (down to zero) or anomalously high (up to unity) values. Such frequencies can lie in the microwave region.     

Reaction of bis(triethylgermyl)cadmium with chalcogens

Conclusions The reaction of sulfur or selenium with bis(triethylgermyl)cadmium in toluene solution gives triethyl-germyl (triethylgermylthio)cadmium or its selenium-containing analog. These compounds in benzene solution are dimeric associates.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 11, pp. 2614–2615, November, 1970.     

Efficiency of raman conversion of XeCl laser radiation in metal vapors

Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 55, No. 1, pp. 80–83, July, 1991.