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The surface thermodynamics of ionic fluids (both ionic liquids and molten salts) are calculated from surface tension data by application of a modified Eötvös Equation, and the results compared with the corresponding values for neutral organic liquids. As may be anticipated and here reported quantitatively, the coulombic interactions within the ionic fluids lead to smaller surface entropies and larger surface enthalpies because of tighter binding among the charged ions. For ionic liquids, an increase in formula volume leads to their surface properties tending towards those of neutral organic liquids, corresponding to a decrease in the strength of the coulombic interactions. Unexpectedly large surface entropies for molten GaCl3, BiBr3, BiCl3 and UF6 suggest that these species may be behaving as freely-spinning pseudo-spherical molecules.

[EN] A molecular scale understanding of the organization and structure of a liquid near a solid surface is currently a major challenge in surface science. It has implications across different fields from electrochemistry and energy storage to molecular biology. Three-dimensional AFM generates atomically resolved maps of solid-liquid interfaces. The imaging mechanism behind those maps is under debate, in particular, for concentrated ionic solutions. Theory predicts that the observed contrast should depend on the tip’s charged state. Here, by using neutrally, negatively, and positively charged tips, we demonstrate that the 3D maps depend on the tip’s polarization. A neutral tip will explore the total particle density distribution (water and ions) while a charged tip will reveal the charge density distribution. The experimental data reproduce the key findings of the theory.

Grain boundary (GB) grooving, induced by surface drift-diffusion and driven by the combined actions of capillary forces and applied uniaxial tensile stresses, is investigated in bi-crystal thin films using self-consistent dynamical computer simulations. A physico-mathematical model, based on the irreversible thermodynamics treatment of surfaces and interfaces with singularities allowed auto-control of the otherwise free-motion of the triple junction at the intersection of the grooving surface and the GB, without having any a priori assumption on the equilibrium dihedral angles. In the present theory, the generalised driving forces for stress-induced surface drift-diffusion arise not only from the usual elastic strain energy density (ESED), but also much stronger elastic dipole tensor interactions (EDTI) between the applied stress field and the mobile atomic species situated at the surface layer and in the GB regions. Accelerated groove-deepening kinetics shows that the surface drift-diffusion enhanced by the applied uniaxial tensile stresses through EDTI is dominant over the GB flux leakage at the triple junction. At high uniaxial stress levels (>= 500MPa for a 100-nm thick copper film), a sequential time-frame for micro-crack nucleation and growth is recorded just before specimen failure took place. These non-equilibrium thermokinetics discoveries (kinetics and energetics) contradict or at least do not support the hypothesis of the steady-state diffusive GB micro-crack formation and propagation due to 'constant' flux drainage through GB enhanced by tensile stresses acting normal to it.

Grain boundary (GB) grooving, induced by surface drift-diffusion and driven by the combined actions of capillary forces and applied uniaxial tensile stresses, is investigated in bi-crystal thin films using self-consistent dynamical computer simulations. A physico-mathematical model, based on the irreversible thermodynamics treatment of surfaces and interfaces with singularities allowed auto-control of the otherwise free-motion of the triple junction at the intersection of the grooving surface and the GB, without having any a priori assumption on the equilibrium dihedral angles. In the present theory, the generalised driving forces for stress-induced surface drift-diffusion arise not only from the usual elastic strain energy density (ESED), but also much stronger elastic dipole tensor interactions (EDTI) between the applied stress field and the mobile atomic species situated at the surface layer and in the GB regions. Accelerated groove-deepening kinetics shows that the surface drift-diffusion enhanced by the applied uniaxial tensile stresses through EDTI is dominant over the GB flux leakage at the triple junction. At high uniaxial stress levels (>= 500MPa for a 100-nm thick copper film), a sequential time-frame for micro-crack nucleation and growth is recorded just before specimen failure took place. These non-equilibrium thermokinetics discoveries (kinetics and energetics) contradict or at least do not support the hypothesis of the steady-state diffusive GB micro-crack formation and propagation due to 'constant' flux drainage through GB enhanced by tensile stresses acting normal to it.

Jan Christer Eriksson and Anatoly I. Rusanov present their views on the article entitled 'incompatibility of the Shuttleworth equation with Hermann's mathematical structure of thermodynamics'. They derive the the general free energy differential expression for a solid fluid interface to continue their discussions. They also focus on discussing the derivation of the Shuttleworth equation within a thermodynamic framework. A pure solid phase composed of a single component is considered for simplicity that is surrounded by a adsorbing and inert gas at low pressure. They also assume that the symmetry of the solid surface is sufficiently high so as to make the surface two-dimensionally isotropic. They have been able to obtain the relevant Helmholtz energy differential expression for an arbitrarily positioned dividing surface by assuming the excess number of moles of the solid component to always remain the same on the basis of the first equation., QC 20141024

The formation and stability of Cu, Ag and Au-induced c(2 x 2) alloys at the Mo(100) and W(100) surfaces have been investigated with low-energy electron microscopy and diffraction. The ordered alloys transform to disordered overlayer structures at elevated temperature. Comparison of the transformation temperatures with energetics obtained from first principles calculations reveals the vibrational entropic contribution to the system free energy that defines alloy thermal stability. Effective Debye temperatures for metal adatoms are determined that exhibit the expected mass and bond strength dependence. (C) 2007 Elsevier B.V. All rights reserved.

The formation and stability of Cu, Ag and Au-induced c(2 x 2) alloys at the Mo(100) and W(100) surfaces have been investigated with low-energy electron microscopy and diffraction. The ordered alloys transform to disordered overlayer structures at elevated temperature. Comparison of the transformation temperatures with energetics obtained from first principles calculations reveals the vibrational entropic contribution to the system free energy that defines alloy thermal stability. Effective Debye temperatures for metal adatoms are determined that exhibit the expected mass and bond strength dependence. (C) 2007 Elsevier B.V. All rights reserved.

We put forward a technique for calculating the surface segregation profile in substitutional disordered alloys. The surface internal energy and the effective bulk and surface chemical potentials are calculated using the full charge density exact muffin-tin orbitals method, combined with the coherent potential approximation. The application of our approach is demonstrated to the close-packed surface of AgcPd1-c random alloys with 0 < c < 1. The surface concentration profile, surface energy and segregation energy are investigated as functions of bulk composition. The present results are compared with former theoretical and experimental data. It is found that at low temperature, Ag segregates to the surface layer for the entire bulk composition range. At 0 K, the subsurface layer contains 100% Pd for c <= 0.4, and somewhat more than (2c - 1) Ag in alloys with c > 0.5. The temperature dependence of the segregation profile is significant for I'd rich alloys and for alloys with intermediate concentrations. At temperatures >= 600 K, the subsurface layer is obtained to be almost bulk like., QC 20100525

The realm of molecular physical chemistry ranges from the structure of matter and the fundamental atomic and molecular interactions to the macroscopic properties and processes arising from the average microscopic behaviour. Herein, the conventional electrodic problem is recast into the simpler molecular problem of finding the electrochemical, real chemical, and chemical potentials of the species involved in redox half-reactions. This molecular approach is followed to define the three types of absolute chemical potentials of species in solution and to estimate their standard values. This is achieved by applying the scaling laws of statistical mechanics to the collective behaviour of atoms and molecules, whose motion, interactions, and properties are described by first principles quantum chemistry. For atomic and molecular species, calculation of these quantities is within the computational implementations of wave function, density functional, and self-consistent reaction field theories. Since electrons and nuclei are the elementary particles in the realm of chemistry, an internally consistent set of absolute standard values within chemical accuracy is supplied for all three chemical potentials of electrons and protons in aqueous solution. As a result, problems in referencing chemical data are circumvented, and a uniform thermochemical treatment of electron, proton, and proton-coupled electron transfer reactions in solution is enabled. The formalism is applied to the primary and secondary radiation damage to DNA bases, e.g., absorption of UV light to yield electronically excited states, formation of radical ions, and transformation of nucleobases into mutagenic lesions as OH radical adducts and 8-oxoguanine. Based on serine phosphate as a model compound, some insight into the direct DNA strand break mechanism is given. Psoralens, also called furocoumarins, are a family of sensitizers exhibiting cytostatic and photodynamic actions, and hence, they are used in photochem

The realm of molecular physical chemistry ranges from the structure of matter and the fundamental atomic and molecular interactions to the macroscopic properties and processes arising from the average microscopic behaviour. Herein, the conventional electrodic problem is recast into the simpler molecular problem of finding the electrochemical, real chemical, and chemical potentials of the species involved in redox half-reactions. This molecular approach is followed to define the three types of absolute chemical potentials of species in solution and to estimate their standard values. This is achieved by applying the scaling laws of statistical mechanics to the collective behaviour of atoms and molecules, whose motion, interactions, and properties are described by first principles quantum chemistry. For atomic and molecular species, calculation of these quantities is within the computational implementations of wave function, density functional, and self-consistent reaction field theories. Since electrons and nuclei are the elementary particles in the realm of chemistry, an internally consistent set of absolute standard values within chemical accuracy is supplied for all three chemical potentials of electrons and protons in aqueous solution. As a result, problems in referencing chemical data are circumvented, and a uniform thermochemical treatment of electron, proton, and proton-coupled electron transfer reactions in solution is enabled. The formalism is applied to the primary and secondary radiation damage to DNA bases, e.g., absorption of UV light to yield electronically excited states, formation of radical ions, and transformation of nucleobases into mutagenic lesions as OH radical adducts and 8-oxoguanine. Based on serine phosphate as a model compound, some insight into the direct DNA strand break mechanism is given. Psoralens, also called furocoumarins, are a family of sensitizers exhibiting cytostatic and photodynamic actions, and hence, they are used in photochem

The realm of molecular physical chemistry ranges from the structure of matter and the fundamental atomic and molecular interactions to the macroscopic properties and processes arising from the average microscopic behaviour. Herein, the conventional electrodic problem is recast into the simpler molecular problem of finding the electrochemical, real chemical, and chemical potentials of the species involved in redox half-reactions. This molecular approach is followed to define the three types of absolute chemical potentials of species in solution and to estimate their standard values. This is achieved by applying the scaling laws of statistical mechanics to the collective behaviour of atoms and molecules, whose motion, interactions, and properties are described by first principles quantum chemistry. For atomic and molecular species, calculation of these quantities is within the computational implementations of wave function, density functional, and self-consistent reaction field theories. Since electrons and nuclei are the elementary particles in the realm of chemistry, an internally consistent set of absolute standard values within chemical accuracy is supplied for all three chemical potentials of electrons and protons in aqueous solution. As a result, problems in referencing chemical data are circumvented, and a uniform thermochemical treatment of electron, proton, and proton-coupled electron transfer reactions in solution is enabled. The formalism is applied to the primary and secondary radiation damage to DNA bases, e.g., absorption of UV light to yield electronically excited states, formation of radical ions, and transformation of nucleobases into mutagenic lesions as OH radical adducts and 8-oxoguanine. Based on serine phosphate as a model compound, some insight into the direct DNA strand break mechanism is given. Psoralens, also called furocoumarins, are a family of sensitizers exhibiting cytostatic and photodynamic actions, and hence, they are used in photochem

The realm of molecular physical chemistry ranges from the structure of matter and the fundamental atomic and molecular interactions to the macroscopic properties and processes arising from the average microscopic behaviour. Herein, the conventional electrodic problem is recast into the simpler molecular problem of finding the electrochemical, real chemical, and chemical potentials of the species involved in redox half-reactions. This molecular approach is followed to define the three types of absolute chemical potentials of species in solution and to estimate their standard values. This is achieved by applying the scaling laws of statistical mechanics to the collective behaviour of atoms and molecules, whose motion, interactions, and properties are described by first principles quantum chemistry. For atomic and molecular species, calculation of these quantities is within the computational implementations of wave function, density functional, and self-consistent reaction field theories. Since electrons and nuclei are the elementary particles in the realm of chemistry, an internally consistent set of absolute standard values within chemical accuracy is supplied for all three chemical potentials of electrons and protons in aqueous solution. As a result, problems in referencing chemical data are circumvented, and a uniform thermochemical treatment of electron, proton, and proton-coupled electron transfer reactions in solution is enabled. The formalism is applied to the primary and secondary radiation damage to DNA bases, e.g., absorption of UV light to yield electronically excited states, formation of radical ions, and transformation of nucleobases into mutagenic lesions as OH radical adducts and 8-oxoguanine. Based on serine phosphate as a model compound, some insight into the direct DNA strand break mechanism is given. Psoralens, also called furocoumarins, are a family of sensitizers exhibiting cytostatic and photodynamic actions, and hence, they are used in photochem

We have studied changes in surface morphology of vicinal Si(111) surfaces with a miscut of 1.3° in the [2̄11] direction after Al deposition at elevated temperatures. The clean surface phase separates into a (111)-oriented phase and a stepped phase. Submonolayer Al deposition at 650°C, the normal preparation temperature of the Al/Si(111)-(√3×√3)R30° structure, only induces minor changes in the surface morphology. However, after Al deposition at temperatures above the order-disorder phase transition temperature, the step bunches break apart into a uniform array of single height steps with an average step-step separation determined by the macroscopic miscut. From a quantitative analysis of the amount of meandering of steps and the terrace width distribution, we determined the diffusivity of steps and the strength of the repulsive step-step interaction. The repulsive interaction between steps is enhanced by the Al adsorption compared to both the high-temperature (1×1) and (7×7) phases of the clean surface. © 1998 Elsevier Science B.V. All rights reserved.

It is well-documented that the (111) surfaces of Mo and W are unstable upon the adsorption of ultra-thin overlayers of some fcc metals and transform to {112} type facets. Using first principles total energy calculations, we found that it is also thermodynamically allowed for Mo(111) to facet to the {110} orientations upon the adsorption of a coating layer of Pd and Pt. An overlayer coverage of about one physical monolayer would be needed to drive the transformation. © 1998 Elsevier Science B.V. All rights reserved.

It is well-documented that the (111) surfaces of Mo and W are unstable upon the adsorption of ultra-thin overlayers of some fcc metals and transform to {112} type facets. Using first principles total energy calculations, we found that it is also thermodynamically allowed for Mo(111) to facet to the {110} orientations upon the adsorption of a coating layer of Pd and Pt. An overlayer coverage of about one physical monolayer would be needed to drive the transformation. © 1998 Elsevier Science B.V. All rights reserved.

We have studied changes in surface morphology of vicinal Si(111) surfaces with a miscut of 1.3° in the [2̄11] direction after Al deposition at elevated temperatures. The clean surface phase separates into a (111)-oriented phase and a stepped phase. Submonolayer Al deposition at 650°C, the normal preparation temperature of the Al/Si(111)-(√3×√3)R30° structure, only induces minor changes in the surface morphology. However, after Al deposition at temperatures above the order-disorder phase transition temperature, the step bunches break apart into a uniform array of single height steps with an average step-step separation determined by the macroscopic miscut. From a quantitative analysis of the amount of meandering of steps and the terrace width distribution, we determined the diffusivity of steps and the strength of the repulsive step-step interaction. The repulsive interaction between steps is enhanced by the Al adsorption compared to both the high-temperature (1×1) and (7×7) phases of the clean surface. © 1998 Elsevier Science B.V. All rights reserved.

It is well-documented that the (111) surfaces of Mo and W are unstable upon the adsorption of ultra-thin overlayers of some fcc metals and transform to {112} type facets. Using first principles total energy calculations, we found that it is also thermodynamically allowed for Mo(111) to facet to the {110} orientations upon the adsorption of a coating layer of Pd and Pt. An overlayer coverage of about one physical monolayer would be needed to drive the transformation. © 1998 Elsevier Science B.V. All rights reserved.

info:eu-repo/semantics/published

info:eu-repo/semantics/published

Low energy ion scattering provides a direct measurement of surface rippling at room temperature, i.e. a relaxation of Au atoms 0.12 Angstrom above the Cu atoms in the outermost layer, which is unambiguously terminated by a mixed and ordered CuAu layer. It is shown that the technique, which is sensitive to the locations of atoms at the first monolayer, is also sensitive to the order-disorder transition in this layer. The occurrence of disorder modifies the arrangement of the atomic rows and then changes the double scattering conditions for low incident angles. As a result, the Au signal decreases significantly at the transition temperature. This effect is continuous and starts at about 50 degrees C below the bulk transition temperature (663 K).