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I. A. Belova F. A. Bol’shchikov Yu. K. Voron’ko A. V. Malov A. V. Popov P. A. Ryabochkina A. A. Sobol’ S. N. Ushakov 《Physics of the Solid State》2008,50(9):1611-1618
This paper reports on the results of the investigation into the intensities of the f-f transitions of Nd3+, Er3+, and Tm3+ ions in calcium niobium gallium garnet (CNGG) crystals. The values of the oscillator strengths and line strengths obtained for hypersensitive transitions and the intensity parameters Ω t of the rare-earth ions in the CNGG crystals are compared with the corresponding quantities for crystals of other garnets and some oxide and fluoride crystals. The assumption is made that an increase in the oscillator strengths and line strengths for the hypersensitive transitions and the intensity parameters Ω2 of the Nd, Er, and Tm ions in the CNGG crystals as compared to those for crystals of other garnets is associated with the specific features revealed in the crystal structure of the calcium niobium gallium garnet, in particular, with the lowering of the symmetry of the positions occupied by rare-earth ions in the crystal structure. 相似文献
76.
A. N. Vodin L. P. Korda A. O. Rastrepina G. E. Tuller I. V. Ushakov 《Bulletin of the Russian Academy of Sciences: Physics》2008,72(6):761-765
The excitation function for the 40Ar(pγ)41K reaction at the accelerated proton energy E p= 450–2700 keV is studied. Positions of 168 resonances identified as levels of the 41K nucleus are observed in this energy range. The data for the proton energy E p < 1 MeV and E p > 2 MeV are obtained for the first time. Relative yields of γ rays observed in the decay of the resonances are calculated from a comparison with the yield of the calibrating resonance at E p= 1102 keV. Total radiation widths of the resonances are calculated on the basis of the data obtained. 相似文献
77.
An artificial nanocomposite medium made by embedding copper nanoparticles covered by copper oxide in a high-pressure polyethylene
matrix is studied. Pioneering experiments are reported aimed at finding the temperature dependences of its insulating properties,
dielectric relaxation time, and activation energy for polarization relaxation. The measurements are taken at a variable signal
applied to the composite. 相似文献
78.
Denis N. Tomilin Maxim D. Gotsko Lyubov N. Sobenina Igor A. Ushakov Boris A. Trofimov 《Tetrahedron letters》2019,60(28):1864-1867
The cycloadducts of menthofuran with acylbromoacetylenes, (3-bromo-1,6-dimethyl-5,6,7,8-tetrahydro-2H-2,4a-epoxynaphthalen-4-yl)(aryl)methanones, rearrange (CHCl3, reflux, 1 h) to 2-(2-acylethyl)benzofurans (along with the expected 2-bromo-3-hydroxy-4,7-dimethyl-5,6,7,8-tetrahydronaphthalene-1-yl)(aryl)methanones) via 2-acylethynylmenthofurans, thus indicating the exceptionally mild and rapid transfer of four hydrogens from a cyclohexane ring to a triple bond through the furan moiety in the key intermediate 2-acylethynylmenthofuran. 相似文献
79.
Doklady Mathematics - We study the properties of α-sets, which are a generalization of convex sets. The relationship between α-sets and weakly convex sets is established in the sense of... 相似文献
80.
Russian Journal of Applied Chemistry - The previously developed procedures for preparing dihydrodicyclopentadiene (DHDCPD) and tetrahydrodicyclopentadiene (THDCPD) are considered comprehensively.... 相似文献