On the photoexcitation of the 2s→2p transition in light muonic atoms

It is known that the energy of the 2s→2p transition of light μ-atoms can be precisely measured by laser spectroscopy. Such measurements provide a good test of quantum electrodynamics predictions. Here we consider how the hyperfine muon-nucleus interaction effects on the photoexcitation of this transition and on the subsequent X-rays emission. Besides the obvious change of the transition energy the hyperfine interaction mixes the 2p 1/2 and 2p 3/2 orbits. This mixing is rather effective in μ-atoms of¹H,⁷Li,⁹Be,¹⁰B and¹¹B. Its taking into account changes the photoexcitation cross-section of electric dipole transitions between the hyperfine components of the 2s and 2p orbits and an angular X-rays distribution as well. These changes prove to be considerable for some transitions. For example, in μ²H and μ⁷Li the cross-section is decreased by factors of two and four respectively. In μ⁹Be it is increased by a factor of two. Moreover, in μ¹H the angular X-rays distribution becomes more anisotropic. Besides the above subject one more question is discussed here. The fact is that the laser experiments can give an information on the residual muon spin polarization at the 2s orbit and on the degree of alignment of the angular μ-atom momentum in this state. The polarization can be determined by measuring an angular correlation between the X-rays emission direction and the momentum of a hard μ-decay electron. The alignment degree can be found by measuring an anisotropy of the angular X-rays distribution.     

Ammonium phosphonium salts

Conclusions Ammonium phosphonium salts are formed when tertiary phosphines are reacted with benzalaniline in the presence of dry HCl.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 3, pp. 719–720, March, 1984.     

Acid-catalyzed formation of hexahomooxacalix[3]arenes

The role of acid catalysis in oxacalix[3]arene synthesis has been investigated. A range of acids were used to optimize the yield of tert-butyloxacalix[3]arene, the most efficient being p-toluenesulfonic acid, which, with local symmetry complementary with that of the lower rim of the calixarene, provides a templating effect.     

Cycloaddition of fluorinated oxazoles

Cycloaddition reactions of polyfluorinated 1,3-oxazoles with cyclic and acyclic alkenes were studied. The results of these reactions were interpreted using quantum chemical calculations. An unusual product, viz., fluorine-containing acylpyrrole, was studied by X-ray diffraction. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 7, pp. 1630–1635, July, 2005.     

An Inverse Problem for a Semilinear Wave Equation

Doklady Mathematics - For the equation $${{u}_{{tt}}} - \Delta u - f(x,u) = 0, (x,t) \in {{\mathbb{R}}^{4}},$$ where $$f(x,u)$$ is a smooth function of its variables and is compact in x, the...     

The Role of Active Oxygen Transfer through the Gas Phase in Propylene Oxidation over a Bismuth–Molybdenum Catalyst

The transfer of atomic oxygen from the surface of bismuth oxide onto molybdenum oxide through the gas phase, including the case when ozone was fed to the catalyst bed, is experimentally studied. It is found that the transfer of atomic oxygen through the gas phase only leads to the formation of the products of complete oxidation of propylene under conditions of heterogeneous propylene oxidation on the mixture of molybdenum and bismuth oxides. No new sites are formed on the surface of molybdenum oxide.     

Condensed heterocycles with a thiazole ring. 14 Nature of the electronic spectra of symmetrical polymethine dyes of the thiazolo[3,4-b][1,2,4]triazine series

Symmetrical mono-, tri-, and pentamethinecyanine dyes with a thiazolo[3,4-b][1,2,4]triazine ring were synthesized. The electron-density distributions in the dye molecules in the ground and first and second excited states were obtained by quantum-chemical calculations. It was established that the first two electron transitions are localized on the same atoms and that charge transfer to the triazine fragment of the molecule is realized in the case of excitation. The degree of participation of the heterocyclic ring in the first electron transition, which is responsible for the color of the dye, decreases with lengthening of the polymethine chain.See [1] for communication 13.Translated from Khimiya Geterotsiklicheskikh Soedinenii, Vol. 24, No. 3, pp. 418–423, March, 1988.     

The hyperfine muon-nucleus interaction andP-odd effects in the one-photon 2s → 1s transition of light muonic atoms

The weak interaction of neutral currents of the negative muon and a nucleus results inP-odd correlations in the one-photon 2s → 1s transition of light muonic atoms. If the standard electroweak model is used, the weak mixing of hyperfine components of the μ-atom 2s and 2p 1/2 orbits makes the main contribution to these correlations. A new mechanism of acting the hyperfine structure on theP-odd correlations is considered in the present work. The fact is that the hyperfine muon-nucleus interaction mixes the 2p 1/2 and 2p 3/2 orbits effectively in light muonic atoms whose nuclei have large quadrupole moments. As a result, two new sublevels arise for each of two valuesF _±=(I ± 1/2) of the total angular μ-atom momentum (I is the nuclear spin). The contributions of these sublevels to theP-odd correlations can be comparable with each other. The most strikes manifestation of the given effect occurs for berillium and boron, where the 2s and 2p 3/2 orbits may have close energies. Taking the above effect into account can lead to considerable modification of results against earlier calculations. In particular, theP-odd correlations can vanish and change sign. They can be additionally increased by a factor of several tens.     

Condensed heterocycles with a thiazole ring.

Derivatives of new condensed heterocyclic systems — pyrido- and quinolino[1,2:3,2]thiazolo[4,5-b]pyrazines — were synthesized by condensation of 2,3-dichloropyrazine with 2-mercaptopyridine and 2-mercaptoquinolines.See [1] for Communicaton 17.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 9, pp. 1276–1278, September, 1990.     

Structure of 1,7-diphenyl-m-carborane

Journal of Structural Chemistry -