Search results for "Films"
showing 10 items of 2839 documents
Transport equations of electrodiffusion processes in the laboratory reference frame.
2006
The transport equations of electrodiffusion processes use three reference frames for defining the fluxes: Fick's reference in diffusion, solvent-fixed reference in transference numbers, and laboratory fluxes in electric conductivity. The convenience of using only one reference frame is analyzed here from the point of view of the thermodynamics of irreversible processes. A relation between the fluxes of ions and solvent and the electric current density is deduced first from a mass and volume balance. This is then used to show that (i) the laboratory and Fick's diffusion coefficients are identical and (ii) the transference numbers of both the solvent and the ion in the laboratory reference fr…
A vacuum cell for obtaining clean surfaces on liquid low melting point metals
1997
Abstract Clean oxide film-free surface of liquid gallium was obtained in a sealed vacuum cell with a glass lid for observation. The cell was evacuated to high vacuum (10 -4 Pa) before admission of liquid and sealing. The surface contamination was about 2–5% of the free area and did not exhibit noticeable increase during several months of storing and employing the cell. The cell described allows observation of surface flows, capillary phenomena and crystallization processes under different conditions.
On the relaxation mechanisms of 6-azauracil
2011
The nonadiabatic photochemistry of 6-azauracil has been studied by means of the CASPT2//CASSCF protocol and double-ζ plus polarization ANO basis sets. Minimum energy states, transition states, minimum energy paths, and surface intersections have been computed in order to obtain an accurate description of several potential energy hypersurfaces. It is concluded that, after absorption of ultraviolet radiation (248 nm), two main relaxation mechanisms may occur, via which the lowest (3)(ππ*) state can be populated. The first one takes place via a conical intersection involving the bright (1)(ππ*) and the lowest (1)(nπ*) states, ((1)ππ*/(1)nπ*)(CI), from which a low-energy singlet-triplet crossin…
Dopamine interaction with a polyamine cryptand of 1H-pyrazole in the absence and in the presence of Cu(ii) ions. Crystal structure of [Cu2(H−1L](ClO4…
2000
The crystal structure of the binuclear Cu2+ complex [Cu2(H−1L)](ClO4)3 ·2H2O of the cryptand L = 1,4,7,8,11,14,17,20,21,24,29,32,33,36-tetradecaazapentacyclo[12.12.12.1 6,9.119,22,1,31,34]hentetraconta-6,9(41), 19(40), 21,31,34(39)-hexaene is presented; evidence for the formation in solution of binary L–dopamine and ternary Cu2+–L–dopamine complexes is presented.
A Density Functional Theory study on gold cyanide interactions: The fundamentals of ore cleaning
2010
We have employed Density Functional Theory calculations to study the adsorption of CN, CN− and KCN on Au(111) and Au(211) surfaces and compare the obtained results to CO. The adsorption of CN, CN−, and KCN are exothermic with respect to the gas-phase moieties, and the adsorption energy increases at steps. Our results show that the binding mechanism of CN− is different from that of CO. The projected LDOS indicates that the bond between the flat surface and CN shows very small overlap between metal and CN states. This overlap increases provided that extra charge is present or low-coordinated Au atoms are available. Charge transfer is analyzed via the Bader method and the Electron Localization…
Analysis and parametric sensitivity of the behavior of overshoots in the concentration of a charged adsorbate in the adsorbed phase of charged adsorb…
2003
In this work, an analysis of the parametric sensitivity of the overshoot in the concentration of the adsorbate in the adsorbed phase, which occurs under certain conditions during an ion-exchange adsorption process, is presented and used to suggest practical implications of the concentration overshoot phenomenon on operational policies and configurations of chromatographic columns and finite bath adsorption systems. The results presented in this work demonstrate and explain how the development of an overshoot in the concentration of the adsorbate in the adsorbed phase could be enhanced or suppressed by (i) varying the diffusion coefficient, D3, of the adsorbate relative to the diffusion coef…
Study of interface diffusion of Ti and TiN PVD layers by Bremsstrahlung-induced AES
1992
The influence of heat treatment in ultrahigh vacuum (UHV) on Ti and TiN layers coated by physical vapour deposition (PVD) has been studied by AES, XPS and bremsstrahlung-induced AES. It could be concluded that up to 500 o C (1 h) the Ti layer does not change significantly. At the TiN/steel substrate interface, however, a counter-diffusion of nitrogen and adventitious oxygen takes place, resulting in partial nitridation of the steel substrate and oxidation of the coating
The Triplet Excimer of Naphthalene: A Model System for Triplet−Triplet Interactions and Its Spectral Properties
2011
Basic concepts of triplet excimer formation and triplet−triplet interactions between molecules with conjugated π-systems are investigated by means of ab initio quantum chemical calculations, employing the second-order coupled-cluster method CC2 and the second-order propagator method ADC(2). The naphthalene dimer turns out to be a very fruitful model system for which weak and strong electronic coupling can be identified depending on the mutual arrangement of the monomer moieties. From geometry optimizations in the excited state, we determine binding energies, including solvent effects, and transient absorption spectra. The most stable T1 conformation turns out to be a face-to-face arrangemen…
Recombination processes in rare-earth doped MAl2O4(M = Ca, Sr) persistent phosphors investigated by optically-detected magnetic resonance
2007
Single crystalline MAl 2 O 4 (M = Ca and Sr) persistent phosphors, which are nominally pure or additionally doped with Eu and Nd or Dy, respectively, were investigated for their recombination luminescence (RL) and microwave-induced changes in the RL at low temperatures. The analysis of the optically-detected electron paramagnetic resonance (EPR) spectra, recorded after ultraviolet excitation at 4.2 K, shows that intrinsic donor and acceptor centres are involved in the recombination process. Spectral dependent RL-EPR measurements on undoped CaAl 2 O 4 (CAO) and SrAl 2 O 4 (SAO) show that we deal with only one donor but at least two different acceptors. The g value of the donor is 1.99 in CAO…
Eu2+ Stabilization in YAG Structure: Optical and Electron Paramagnetic Resonance Study
2016
A set of Eu-doped Y3Al5O12 (YAG) phosphors in the powder form was successfully synthesized by multiple-step solid-state reaction under the reducing Ar:5%H2 atmosphere. Their physical properties were investigated by means of X-ray diffraction, time-resolved luminescence spectroscopy, and electron paramagnetic resonance (EPR). Special attention was given to well-grounded confirmation of Eu2+ occurrence in the YAG structure. X-ray diffraction confirmed the presence of a major YAG phase in all samples. The influence of Eu concentration, form of doping (EuS, EuF2, or Eu2O3) and number/form of annealing steps was studied. Corresponding characteristics were measured and evaluated in a broad temper…