Electron capture to continuum in collisions of bare projectiles with Ne targets

Abstract. We have investigated the cusp resulting from electron capture to the continuum of 1.25-5 MeV m u- ' fully stripped hydrogen and oxygen as a function of the collision energy and the detector angular resolution B o. It is revealed that the characteristic cusp shape parameters depend strongly on the experimental resolution. Our experimental data are "pared with the second-order Born theory and the impulse approximation. Both theories mnhrm the 8, dependence of the shape parameters and gjve a reasonable descrip-lion of the cusp asymmetry. However, theory tends to overestimate the absolute cross sections, in particular in the case of oxygen. 1

Electron-spectroscopic investigation of metal-insulator transition in Sr2Ru1-xTixO4 (x=0.0-0.6)

We investigate the nature and origin of the metal-insulator transition in Sr2Ru1-xTixO4 as a function of increasing Ti content (x). Employing detailed core, valence, and conduction band studies with x-ray and ultraviolet photoelectron spectroscopies along with Bremsstrahlung isochromat spectroscopy, it is shown that a hard gap opens up for Ti content greater than equal to 0.2, while compositions with x<0.2 exhibit finite intensity at the Fermi energy. This establishes that the metal-insulator transition in this homovalent substituted series of compounds is driven by Coulomb interaction leading to the formation of a Mott gap, in contrast to transitions driven by disorder effects or band flling.Comment: Accepted for publication in Phys. Rev.

Antisolvent addition at extreme conditions

This article describes the use of antisolvent addition at high-pressure to aid precipitation and recovery of high-pressure phases to ambient pressure. Paracetamol (PCM) was used as a model system to demonstrate the principle due to the extensive literature of paracetamol at high-pressure and ambient pressure. We have observed that we are able to recover the orthorhombic form of paracetamol to ambient pressure using this technique, although solvent-mediated transformations are a hurdle. During this investigation we observed a new methanol solvate of paracetamol that is simlar in structure to the known form. The methanol solvate is stable to 0.2 GPa before transformation to the orthorhombic form that is known to be the stable form at high pressure

Understanding complex magnetic order in disordered cobalt hydroxides through analysis of the local structure

In many ostensibly crystalline materials, unit-cell-based descriptions do not always capture the complete physics of the system due to disruption in long-range order. In the series of cobalt hydroxides studied here, Co(OH)$_{2-x}$(Cl)$_x$(H$_2$O)$_{n}$, magnetic Bragg diffraction reveals a fully compensated N\'eel state, yet the materials show significant and open magnetization loops. A detailed analysis of the local structure defines the aperiodic arrangement of cobalt coordination polyhedra. Representation of the structure as a combination of distinct polyhedral motifs explains the existence of locally uncompensated moments and provides a quantitative agreement with bulk magnetic measurements and magnetic Bragg diffraction

Time-dependent Hamiltonian estimation for Doppler velocimetry of trapped ions

The time evolution of a closed quantum system is connected to its Hamiltonian through Schroedinger's equation. The ability to estimate the Hamiltonian is critical to our understanding of quantum systems, and allows optimization of control. Though spectroscopic methods allow time-independent Hamiltonians to be recovered, for time-dependent Hamiltonians this task is more challenging. Here, using a single trapped ion, we experimentally demonstrate a method for estimating a time-dependent Hamiltonian of a single qubit. The method involves measuring the time evolution of the qubit in a fixed basis as a function of a time-independent offset term added to the Hamiltonian. In our system the initially unknown Hamiltonian arises from transporting an ion through a static, near-resonant laser beam. Hamiltonian estimation allows us to estimate the spatial dependence of the laser beam intensity and the ion's velocity as a function of time. This work is of direct value in optimizing transport operations and transport-based gates in scalable trapped ion quantum information processing, while the estimation technique is general enough that it can be applied to other quantum systems, aiding the pursuit of high operational fidelities in quantum control.Comment: 10 pages, 8 figure

Theory and computation of directional nematic phase ordering

A computational study of morphological instabilities of a two-dimensional nematic front under directional growth was performed using a Landau-de Gennes type quadrupolar tensor order parameter model for the first-order isotropic/nematic transition of 5CB (pentyl-cyanobiphenyl). A previously derived energy balance, taking anisotropy into account, was utilized to account for latent heat and an imposed morphological gradient in the time-dependent model. Simulations were performed using an initially homeotropic isotropic/nematic interface. Thermal instabilities in both the linear and non-linear regimes were observed and compared to past experimental and theoretical observations. A sharp-interface model for the study of linear morphological instabilities, taking into account additional complexity resulting from liquid crystalline order, was derived. Results from the sharp-interface model were compared to those from full two-dimensional simulation identifying the specific limitations of simplified sharp-interface models for this liquid crystal system. In the nonlinear regime, secondary instabilities were observed to result in the formation of defects, interfacial heterogeneities, and bulk texture dynamics.Comment: first revisio

Elasticity of smectic liquid crystals with focal conic domains

We study the elastic properties of thermotropic smectic liquid crystals with focal conic domains (FCDs). After the application of the controlled preshear at different temperatures, we independently measured the shear modulus G' and the FCD size L. We find out that these quantities are related by the scaling relation G' ~ \gamma_{eff}/L where \gamma_{eff} is the effective surface tension of the FCDs. The experimentally obtained value of \gamma_{\rm eff} shows the same scaling as the effective surface tension of the layered systems \sqrt{KB} where K and B are the bending modulus and the layer compression modulus, respectively. The similarity of this scaling relation to that of the surfactant onion phase suggests an universal rheological behavior of the layered systems with defects.Comment: 14 pages, 7 figures, accepted for publication in JPC

Nova tehnologija proizvodnje magnezijevih traka i limova

A new production technology for magnesium strip, based on twin-roll-casting and strip rolling was developed in Freiberg Germany. By means of this economic method it is possible to produce strips in deep drawing quality with good forming properties in order to satisfy the request for low cost Mg sheets in the automotive and electronic industry. Both, coils as single sheets, were manufactured and rolled to a thickness of 1mm(0,5 mm). The technology of the new process and the properties of the twin-roll-casted material and the final sheets are presented.Nova tehnologija proizvodnje magnezijevih traka i limova. Nova tehnologija proizvodnje magnezijevih traka utemeljena dvostruko-valjanje-lijevanje i valjanje trake je razvijeno u Freibergu-Njemačka. Motri se, ovom ekonomičnom metodom je moguća proizvoditi trake za duboko izvlačenje, sa dobrim plastičnim svojstvima uz zadovoljavajući zahtjev za nisku cijenu Mg trake za automobilsku i elektronsku industriju. Oboje, svitak i pojedinačne trake su poizvedene i valjane do debljine stjenke 1mm(0,5 mm). Prikazuje se tehnologija novog postupka i svojstva dvostrukog valjanog-lijevačkog materijala i završnih traka

Nova tehnologija proizvodnje magnezijevih traka i limova

A new production technology for magnesium strip, based on twin-roll-casting and strip rolling was developed in Freiberg Germany. By means of this economic method it is possible to produce strips in deep drawing quality with good forming properties in order to satisfy the request for low cost Mg sheets in the automotive and electronic industry. Both, coils as single sheets, were manufactured and rolled to a thickness of 1mm(0,5 mm). The technology of the new process and the properties of the twin-roll-casted material and the final sheets are presented.Nova tehnologija proizvodnje magnezijevih traka i limova. Nova tehnologija proizvodnje magnezijevih traka utemeljena dvostruko-valjanje-lijevanje i valjanje trake je razvijeno u Freibergu-Njemačka. Motri se, ovom ekonomičnom metodom je moguća proizvoditi trake za duboko izvlačenje, sa dobrim plastičnim svojstvima uz zadovoljavajući zahtjev za nisku cijenu Mg trake za automobilsku i elektronsku industriju. Oboje, svitak i pojedinačne trake su poizvedene i valjane do debljine stjenke 1mm(0,5 mm). Prikazuje se tehnologija novog postupka i svojstva dvostrukog valjanog-lijevačkog materijala i završnih traka

Hidden solvates and transient forms of trimesic acid

This article discusses the formation of trimesic acid (TMA) solvates with ethanol, isopropyl alcohol and dimethylformamide via liquid-assisted grinding and slurry experiments. Through the use of X-ray diffraction methods, we highlight the formation of a new ethanol solvate of TMA that completes the series of alcohol solvates observed, a temperature-induced phase transition in the isopropyl alcohol solvate between 233 K and 243 K, and a transient 1:3 solvate with dimethylformamide that mimics a previously identified dimethylsulfoxide solvate. The alcohol structures possess a TMA framework that is geometrically similar where the intermolecular energies between TMA molecules are equivalent. We have observed that increasing the length of the alcohol induces an increase in the distortion of the TMA framework to accommodate the longer alkyl tails