Nuclear moments around the Z=40 shell closure:91mY,95Zr and97Nb

Magnetic moments around the Z=40 shell closure have been established using nuclear magnetic resonance on oriented nuclei (NMR/ON) in iron. From the resonance frequencies we established |μ(⁹¹Y;9/2⁺)|=5.96(6)μ_N, |μ(⁹⁵Zr;5/2⁺)|= 1.103(23)μ_N, | μ(⁹⁷Nb;9/2⁺)| = 6.153(5)μ_N. From the electric quadrupole alignement of⁹⁵Zr+⁹⁵Nb in a Zr single crystal Q(⁹⁵Zr)=+0.29(5)b and Q(⁹⁵Nb)<0 have been derived. The results obtained are discussed using the Nilsson deformed single particle model. It is shown that for certain deformation regions, a measurement of the magnetic moment can give information on the nuclear quadrupole deformation. the NICOLE-ISOLDE Collaboration, CERN     

具有切向控制的局部四点插值曲线设计方法

Ｎｉｒａ Ｄｙｎ等提出的四点插值法是一种典型的自由曲线离散造型方法，但该方法不能控制插值点的切向。本文利用薄板样很可能 量的极小化原理给出了具有切向控制的四点分插值条件。用户可以方便地交互控制任一插值点的切向，使得四点插值法更为有效和实用。     

Evidence for intruder states in111Rh

Levels in¹¹¹Rh have been investigated via the γ -rays following the β^?-decay of 2.1 s¹¹¹Ru. The Ru activity was produced in the fission of²⁴⁹Cf and separated chemically from the fission product mixture. The emitted γ-rays were studied by γ singles and γ(t) coincidence measurements. Evidence for intruder states in¹¹¹Rh has been obtained. Their properties are discussed and compared with those in the lighter Rh isotopes.     

On martingale limit theory and strong convergence results for stochastic approximation procedures

The analysis of asymptotic behaviour of stochastic approximation procedures rests heavily on the use of martingale limit theory, although explicit recognition of this situation is notable for its absence in the literature. This point is emphasized and in illustration a martingale iterated logarithm result is used to obtain strong convergence results of iterated logarithm type for the basic Robbins–Monro and Kiefer–Wolfowitz procedures.     

Nuclear structure of the heavyN=82 isotones:144Sm and146Gd

For single-closed shell nuclei with a large number of extra-protons, outside theZ=50,N=82 double-closed shell nucleus, a standard shell-model calculation yields dimensions of the Hamiltonian matrices beyond the scope of present computer technology. A quasi-particle (QP) calculation however, is able to describe the most important proton-excitations in a much restricted configuration space. Extended BCS+TDA calculations are performed on the single-closed shell¹⁴⁴Sm and¹⁴⁶Gd nuclei with a Gaussian force as effective two-body interaction. The influence of the nonconservation of the exact number of extra-protons in the BCS-approach is studied by performing a projection onto the states with an exact number of extra-protons (BCS+P). The first excited 2⁺, 4⁺ and 6⁺ states in¹⁴⁶Gd are described mainly by the (1g7/2) ₀ ⁸ (2d5/2) ₀ ⁴ \((1h11/2)_{J^\pi }^2 \) configuration.     

Au dimers on thin MgO(001) films: flat and charged or upright and neutral?

A combination of low temperature scanning tunneling microscopy (STM) and theoretical calculations is used to investigate Au dimers, supported on thin MgO(001) films, whose thickness was chosen such that charge transfer from the Ag substrate to the deposited Au is possible. Au dimers exist not only in an upright geometry--as theoretically predicted to be the most stable configuration--but also as flat lying dimers which populate a manifold of different azimuthal orientations. Apart from the difference in adsorption configurations, these two isomers exhibit rather different electronic structures: while upright dimers are neutral, flat ones are charged.     

Crossover from three-dimensional to two-dimensional geometries of Au nanostructures on thin MgO(001) films: a confirmation of theoretical predictions

In this Letter, we report a low-temperature scanning tunneling microscopy study aiming to explore the adsorption properties of Au with respect to the thickness of supported MgO films. For different MgO film thicknesses (3 ML and 8 ML), we find significant differences in the distribution of Au adsorption sites and in the Au cluster geometry, in line with recent calculations and electron paramagnetic resonance experiments. On the surface of thick MgO films or unsupported MgO, Au adsorbs on O sites [Phys. Rev. Lett. 96, 146804 (2006)], and the equilibrium cluster geometry is three-dimensional. In contrast, on thin MgO films, the calculations predicted (i) a change of the preferred Au nucleation site [Phys. Rev. Lett. 94, 226104 (2005)] and (ii) a stabilization of two-dimensional Au cluster geometries [Phys. Rev. Lett. 97, 036106 (2006)].     

The atomic structure of a metal-supported vitreous thin silica film

Clear as glass: The atomic structure of a metal-supported vitreous thin silica film was resolved using low-temperature scanning tunneling microscopy (STM). Based on the STM image, a model was constructed and the atomic arrangement of the thin silica glass determined (see picture). The total pair correlation function of the structural model shows good agreement with diffraction experiments performed on vitreous silica.