The magnetic moment of the first-excited 2+ state in 18O

The magnetic decoupling method, applied to highly ionized nuclear-excited ¹⁸O atoms, has yielded for the 198 MeV 2⁺ state the value |g| = 0.35 ± 0.04. In conjunction with the recently determined negative sign, this value agrees well with weak j-j coupling predictions.     

Measuring the uniaxial strain of individual single-wall carbon nanotubes: resonance Raman spectra of atomic-force-microscope modified single-wall nanotubes

Raman spectroscopy is used to measure the strain in individual single-wall carbon nanotubes, strained by manipulation with an atomic-force-microscope tip. Under strains varying from 0.06%-1.65%, the in-plane vibrational mode frequencies are lowered by as much as 1.5% (40 cm(-1)), while the radial breathing mode (RBM) remains unchanged. The RBM Stokes/anti-Stokes intensity ratio remains unchanged under strain. The elasticity of these strain deformations is demonstrated as the down-shifted Raman modes resume their prestrain frequencies after a nanotube is broken under excessive strain.     

Light-induced aminocarbene to imine dyotropic rearrangement in a chromium(0) center: an unprecedented reaction pathway

1,2-Dyotropic rearrangement can be induced by irradiation of properly functionalized Fischer carbenes. This novel reaction takes place by a stepwise mechanism and with double inversion of configuration at the static scaffold. Good yields are obtained with both cyclic and acyclic structures, thus suggesting that this unprecedented transformation can be extended to other organometallic systems.     

Distribution of Subdominant Eigenvalues of Random Matrices

We mainly investigate the behavior of the subdominant eigenvalue of matrices B= (b _i,j)^n,n whose entries are independent random variables with an expectation Eb _i,j=1/n and with a variance n c/n ² for some constant c 0. For such matrices we show that for large n, the subdominant eigenvalue is, with great probability, in a small neighborhood of 0. We also show that for large n, the spectral radius of such matrices is, with great probability, in a small neighborhood of 1.     

Facile N≡N Bond Cleavage by Anionic Trimetallic Clusters V3−xTaxC4− (x=0–3): A DFT Study

Activation of N₂ on anionic trimetallic V_3−xTa_xC₄⁻ (x=0–3) clusters was theoretically studied employing density functional theory. For all studied clusters, initial adsorption of N₂ (end-on) on one of the metal atoms (denoted as Site 1) is transferred to an of end-on: side-on: side-on coordination on three metal atoms, prior to N₂ dissociation. The whole reaction is exothermic and has no global energy barriers, indicating that the dissociation of N₂ is facile under mild conditions. The reaction process can be divided into two processes: N₂ transfer (TRF) and N−N dissociation (DIS). For V-series clusters, which has a V atom on Site 1, the rate-determining step is DIS, while for Ta-series clusters with a Ta on Site 1, TRF may be the rate-determining step or has energy barriers similar to those of DIS. The overall energy barriers for heteronuclear V₂TaC₄⁻ and VTa₂C₄⁻ clusters are lower than those for homonuclear V₃C₄⁻ and Ta₃C₄⁻, showing that the doping effect is beneficial for the activation and dissociation of N₂. In particular, V−Ta₂C₄⁻ has low energy barriers in both TRF and DIS, and it has the highest N₂ adsorption energy and a high reaction heat release. Therefore, a trimetallic heteronuclear V-series cluster, V−Ta₂C₄⁻, is suggested to have high reactivity to N₂ activation, and may serve as a prototype for designing related catalysts at a molecular level.     

High Resolution Synchrotron Diffraction Study on Charge Density Distribution of Ampicillin Trihydrate

Charge density distribution in ampicillin trihydrate was investigated experimentally. Results were compared with the quantum calculations using density functional theory. The charge derived properties including Mulliken atomic charges, dipole moment, and molecular electrostatic potential were calculated. The multipole analysis was done for the refinement of experimental population parameters. The structure factors obtained from multipole treatment were used for the construction of Fourier maps. Topological properties of the charge distribution were discussed and the characteristics of (3,-1) critical points were analyzed.     

The non-linear,dynamic response of an impulsively loaded circular plate with a central hole

A numerical method, called Direct Analysis, is described and applied to solve the problem of a plate undergoing a large impulsive load. For generality, an expanded, non-linear form of the equations of motion is used and shear correction and rotatory inertia are considered. The wave speeds are calculated from the non-linear equations and appropriate boundary conditions are applied so that reflected waves are included. The results for two types of step loading pulses are presented and compared with previously presented solutions. The response of the plate is discussed and conclusions as to the effects of the non-linearities are given.