A Potential-Induced Transformation in the Double Electrical Layer on the Rhenium Electrode in Alkali Chloride Melts

Structural transformations in the adsorption layer caused by an electric potential are investigated using the experimental data on the capacitance of a double electric layer for a rhenium electrode in molten sodium, potassium and cesium chlorides at 1093 K. Likening the double electric layer to a flat capacitor, as well as the effective length of the shielding of the electrode charge and changes in the charge sign depending on the applied potential are estimated. It is found that near the minimum potential of the capacitance curve, the shielding length decreases proportionally to the square of the potential due to the deformation of the double layer. The deformation reaches critical values at the potentials of −0.65, −0.38 and −0.40 V for the Re|NaCl, Re|KCl and Re|CsCl systems respectively, and decreases sharply at more positive potentials. The analysis of the dependence of the charge density on the electrode revealed the effect of shielding of potential-induced rhenium cations by salt phase anions. The strong Raman-active Re–Cl stretching mode was observed at 292 cm−1. This can be explained by the transfer of anions across the interface resulting in the formation of ordered layers of ion associations (possibly, ReXn(n − 1)−) on a positively charged surface.

Investigation on steering of ultrarelativistic $$e^{\pm }$$ beam through an axially oriented bent crystal

An investigation on stochastic deflection of high-energy charged particles in a bent crystal was carried out. In particular, we investigated the deflection efficiency under axial confinement of both positively and negatively charged particles as a function of the crystal orientation, the choice of the bending plane, and of the charge sign. Analytic estimations and numerical simulations were compared with dedicated experiments at the H4 secondary beam line of SPS North Area, with 120 GeV/c electrons and positrons. In the work presented in this article, the optimal orientations of the plane of bending of the crystal, which allow deflecting the largest number of charged particles using a bent crystal in axial orientation, were found.

Effect of Hofmeister Anions on Interfacial Properties of Mica Surface in Concentrated Aqueous Solution

The electric double layer (EDL) formed at the water/solid interface is the key to understanding a wide variety of natural phenomena; and nowadays, this knowledge may lead to ideas for technological innovations in the industrial and biomedical fields. The properties of the EDL on a surface directly determine the performance of an EDL-based device. In electrolyte solution, the coions with the same charge sign with the surface are usually ignored. However, they are expected to make a considerable contribution in concentrated conditions when ionic specific effects should be considered. Herein, we investigated the effect of anions in the Hofmeister series, including kosmotropes (Ac−), chaotropes (I−), and intermediate (Cl−), on the properties of the EDL on a negatively charged mica surface by observing intersurface forces using the surface forces apparatus (SFA). The SFA results indicated that at a concentration of 1 M and above, the effect of the monovalent anions in the sodium solutions were mainly correlated with their hydration behaviors. Exclusively in the solutions with strongly hydrated anions, we measured the abnormal long-range repulsions in the diffuse layer region farther away from the surface. By further investigating the solutions with kosmotropic divalent SO42− at relatively low concentrations, we may attribute the observation to the formation of ion pairs and hydrodynamic effects in the presence of concentrated kosmotropic anions. Moreover, these anions can also contribute to the formation of a complete and stable hydration layer near the surface. This work demonstrates the considerable effects of Hofmeister anionic coions on the properties of a simple colloid interface, which has attracted little attention in the past. Therefore, further investigations are desirable in the development of electrolytes and surface materials for the promising EDL-based technologies.

Strongly Intensive Observables in the Model with String Fusion

We calculate the strongly intensive observables for multiplicities in two rapidity windows in the model with independent identical strings taking into account the charge sign of particles. We express the observables through the string pair correlation functions describing the correlations between the same and opposite sign particles produced in a string decay. We extract these charge-wise string two-particle correlation functions from the ALICE data on the forward-backward correlations and the balance function. Using them we predict the behavior of the charge-wise strongly intensive observables in the model with independent identical strings. We also show that the observable between multiplicities in two acceptance windows separated in rapidity, which is a strongly intensive in the case with independent identical strings, loses this property, when we take into account string fusion effects and a formation of strings of a few different types takes place in a collision. We predict the changes in the behaviour of this observable with energy and collision centrality, arising due to the string fusion phenomena.