Electron capture decay of 51 min191Hg

The decay¹⁹¹Hg→¹⁹¹Au was investigated by measuring γ-ray spectra, conversion electron spectra, and coincidence spectra, as well as lifetimes in the second region. The parent isotope¹⁹¹Hg was produced by the reaction¹⁹⁷Au (d, 8n) withE _d =80 MeV. About 80 γ-transitions of this decay were observed. Multipolarities of the more intense transitions were determined. An isomeric state of 0.92±0.11 s half-life was found in¹⁹¹Au. A level scheme for¹⁹¹Au is suggested. The measured γ-transitions are attributed to the decay of a 13/2⁺ isomeric state of¹⁹¹Hg; its half-life was found to be 50.8 ±1.5 min. The core excitation model was used to discuss some features of the level structure in¹⁹¹Au.     

Interatomic bonds and the tensile anisotropy of trialuminides in the elastic limit: a density functional study for Al3(Sc,Ti, V,Cr)

The tensile anisotropy in the elastic limit of Al₃(Sc,?Ti,?V,?Cr) intermetallic compounds in both the L1₂ and D0₂₂ crystal structure has been investigated using first-principles density-functional calculations. In both crystal structures the main bonding character comes from the saturation of dominant d ³ (L1₂) and d ⁴ (D0₂₂) hybrid orbitals located on the TM atoms. The series Al₃Sc?→ Al₃V corresponds to gradual d-band filling and leads to a gradual increase of bond-strength and covalent bond formation. The magnetism of Cr breaks this trend in the Al₃Cr compound (for both ferromagnetic and antiferromagnetic configurations). In this series, a trend towards an increased anisotropy of the elastic constants, Young modulus Y and Poisson ratio ν is observed. The easy and hard directions of tension can be simply identified by the variation of Y, which corresponds to the presence or absence of covalently bonded–Al–TM–chains. A high anisotropy of the Poisson ratio arises also from an alternation of atoms in the lateral directions and can be understood in the same terms.