Strong Interactions in Strange Exotic Atoms

Strong interaction level shifts and widths in ^- and K^- atoms have been analyzed. The phenomenological density dependent approach as well as the relativistic mean field (RMF) model yield nucleus optical potentials with a repulsive real part in the nuclear interior. This has important consequences for the spectroscopy of hypernuclei. The study of K^- atoms cannot resolve the depth of the K^- nucleus potential. The fits to the kaonic atom data are satisfactory for both the relatively shallow potentials derived from chiral models and for the deep potentials based on the phenomenological and RMF analyses.     

A study by molecular mechanics of the geometric isomers of benzene hexachloride,benzene tetrachloride,and naphthalene tetrachloride

The MM 2 molecular mechanics force field, as modified for halogens, is able to predict the structures, dipole moments, and energies of the isomers of benzene hexachloride. For benzene tetrachloride and naphthalene tetrachloride the field exaggerates the stability of conformers with axial chlorine, but gives satisfactory results if the field is modified to allow for interaction between electronegative substituents and the π electrons.     

Reaction of [P3N3Cl4(NH2)2] with [HN(POCl2)2]; The crystal structure of the phosphazenium salt [P3N3HCl4(NH2)2]+[N(POCl2)2]−

The reaction of diaminotetrachloro-cyclotriphosphazene with tetrachloride of μ-imino-diphosphoric acid leads to the formation of the salt-like compound [P₃N₃HCl₄(NH₂)₂]⁺[N(POCl₂)₂]⁻ which identity was unambiguously established by means of X-ray structure analysis. The structure is composed of [P₃N₃HCl₄(NH₂)₂]⁺ cations and [N(POCl₂)₂]⁻ anions joined by a system of H-bonds. As in other phosphazenium salts, the protonation of the ring N atom leads to significant changes in the endocyclic P N bond lengths.     

Recycling of isotopically modified molybdenum from irradiated CerMet nuclear fuel: part 4—technetium separation from concentrated molybdate solution

Uranium-free molybdenum-based CerMet fuels can be applied for transmutation of minor actinides in GEN IV reactors or ADS. In a reprocessing concept designed in the first paper in this mini-series (Mareš and John in J Radioanal Nucl Chem 320(1):227–233, 2019. https://doi.org/10.1007/s10967-019-06456-2) the residual radionuclidic impurities need to be separated from slightly alkaline (pH 9.1) highly concentrated ammonium molybdate solutions. Screening tests of technetium extraction onto three extraction chromatographic materials were performed in present study. Solid extractants based on Aliquat^® 336 turned out to be the most promising for Tc extraction from molybdenum solutions both from the point of view of the extraction kinetics and the practical extraction capacity. The overall results of this mini-series allowed to conclude that if the molybdenum recycling concept proposed is adopted, separation of the residual radionuclidic impurities should not represent a significant problem.

     

Electron states of manganese luminescence centres in A1N

The energy spectrum of manganese luminescence centres in AlN was studied by means of excitation and emission spectra. Two regions of excitation were found: in the first region (from 40 000 to 31 000 cm^–1) excitation occurs as a result of transfer of energy from other impurity centres to the manganese centres; in the second region (from 26 000 to 17 000 cm^–1) the manganese centres are excited directly. In the excitation band with a peak at about 19 200 cm^–1 a phonon structure was observed having a temperature dependence analogous to that of the phonon structure of the emission band. The phonon energy at excitation differs from that at emission (_exc260 cm^–1, _em160 cm^–1). A scheme of electron-phonon levels of manganese centres in AlN is presented, and problems relating to the structure of these centres are discussed.Na Slovance 2, Praha 8, Czechoslovakia.The authors would like to thank Dr. L. Kratina and Dr. F. Kubec (Institute of Radio Engineering and Electronics, Czechoslovak Academy of Sciences), who kindly performed the EPR measurements, and to Professor M. Trlifaj and Dr. J. Pastrák for valuable discussions.     

Spectral analysis of 208Pb muonic atom

We have applied to the ²⁰⁸Pb muonic atom a series of recurrence relations relating the moments of the ground-state density and the energy differences between the 1s level and the states of the line. The large amount of precise experimental data and the electromagnetic character of the interaction allow a detailed test of the method for determining the ground-state density and reconstructing the local equivalent potential. Though the present work is limited to the study of the efficiency for a given trial density, it results in a semi-quantitative analysis with an accuracy better than 1%. Received: 18 December 2000 / Accepted: 18 April 2001