No abstract

A Mossbauer-spectroscopy study of amorphous Fe Ge&, with 0. 11&x &0.72, was performed to measure the hyperfine-field parameters at 22 and 295 K. The distributions of quadrupole splitting suggest that for x & 0.2, the structure of the alloys is homogeneous and Fe atoms probably occupy the interstices of the Ge tetrahedral structure. For concentrations of x &0.4, however, hyperfine-field parameters seem to indicate that the alloys contain a mixture of short-range-order phases, with the average hyperfine magnetic field rising sharply with concentration. The resulting analysis of isomer shift, in terms of the model of Miedema and Van der Woude [physics B 100, 145 {1980)],shows the Fe magnetic moment to be strongly influenced by hybridization and intra-atomic charge redistribution.

Measurements are reported of orientation asymmetries in the forward-angle differential cross sections for pion single-charge-exchange scattering of aligned and unaligned ,65 Ho nuclei. The extrapolated 0° asymmetry of -0.022 ±0.024 indicates a quadrupole deformation ratio Pi/Pi =0.84 ±0.08. This result conflicts with the predictions of the best available Hartree-Fock models.

We report asymmetries in the forward-angle difFerential cross sections for pion single-chargeexchange scattering from oriented and unoriented Ho nuclei. These asymmetries are directly related to the neutron deformation of a nucleus that has a large charge quadrupole moment. The measured asymmetry extrapolated to 0' is -0.020 6 0.024. In the model of Chiang and Johnson, this value implies a quadrupole deformation ratio P2/Pz = 0.84+0.08, indicating that the excess neutrons are less deformed than the protons. This result conSicts with the predictions of the best available Hartree-Fock models based on Skyrme interactions. We also report on asymmetries of the nonresonant continuum and of the giant dipole resonances.Elastic electron-scattering experiments provide the best systematic information on the nuclear shapes in that, to 6rst order, the momentum-transfer dependence of the cross sections is the Fourier transforxn of the charge distribution. Auxiliary information and constraints are also obtained kom inelastic-scattering experiments for which, within the &amework of vibrational or rotational models, the cross sections are proportional to the squares of the Pr, coefBcients. The quadrupole deformation moment Pz 0556-2813/94/50(2)/909

No abstract

No abstract

No abstract

No abstract