Search results for "Faces"
showing 10 items of 3167 documents
Micellization in Model Surfactant Systems
1999
Formation of micelles in model lattice surfactant systems was studied by a novel methodology based on grand-canonical Monte Carlo simulations. The methodology involves combining free-energy information from a series of simulations in small systems by histogram reweighting. The solution osmotic pressure as a function of overall volume fraction of surfactant shows a sharp break at the critical micelle concentration (cmc) at sufficiently low temperatures. Studies in larger systems at appropriate values of the surfactant chemical potential are used to investigate the size distribution of micellar aggregates. The methodology allows for a clear distiction between micellization and macroscopic pha…
Structure and luminescence of GaN layers
2001
Abstract GaN films grown on 〈1 1 1〉 Si substrate by means of low pressure MOCVD technique in a horizontal flow quartz reactor are characterized by different thin layer analysis methods. The polycrystalline hexagonal structure of the GaN layers has been checked by means of grazing incidence X-ray diffractometry and IR spectroscopy. Cathodoluminescence (CL) spectra and their time kinetics are studied. The mean decay time of the 3.44 eV UV bound exciton transition is below 1 ns, whereas the 3.26 eV violet band shows a slow hyperbolical decay over about 1 μs. A third yellow band appears at 2.12 eV due to transitions via localized states.
Superradiance and Exciton (De)localization in Light-Harvesting Complex II from Green Plants?
2002
Fluorescence quantum yield and fluorescence lifetime measurements were performed on trimeric light-harvesting complex II (LHCII) from spinach in the temperature range 7−293 K. From the results the radiative rate was calculated, which is related to the amount of delocalization of excitations over different pigments because of intermolecular interactions. The emitting dipole strength of LHCII is very similar to that of unbound Chl a, and it appears to be almost independent of temperature. The apparent increase of the radiative rate upon lowering the temperature can largely be explained by the shrinking of the sample. It is concluded that at all temperatures the amount of exciton delocalizatio…
Synergistic effect of ligating and ionic functions, prearranged on a calix[4]arene.
2006
The covalent attachment of two CMPO-functions and two anionic Cosan groups to the narrow rim of tert-butylcalix[4]arene leads to a dramatic increase of the extraction efficiency for the cone isomer; Am(3+) is removed from 5 x 10(-8) M solution to more than 99% by a single extraction step with a 3 x 10(-6) M solution of the calixarene.
Extraction of lanthanides and actinides by a magnetically assisted chemical separation technique based on CMPO-calix[4]arenes
2001
A novel particulate system carrying CMPO ligands pre-organised on a calixarene scaffold has been synthesised and demonstrated to extract Eu3+, Am3+ and Ce3+ at high efficiency from simulated nuclear waste streams.
Contact Potentials, Fermi Level Equilibration, and Surface Charging.
2016
This article focuses on contact electrification from thermodynamic equilibration of the electrochemical potential of the electrons of two conductors upon contact. The contact potential difference generated in bimetallic macro- and nanosystems, the Fermi level after the contact, and the amount and location of the charge transferred from one metal to the other are discussed. The three geometries considered are spheres in contact, Janus particles, and core-shell particles. In addition, the force between the two spheres in contact with each other is calculated and is found to be attractive. A simple electrostatic model for calculating charge distribution and potential profiles in both vacuum an…
Energy distribution of plasma-assisted electron and ion emission from TGS single crystals
2008
Abstract Electron and ion emission accompanying non-thermal plasma processes, produced at the surface of TGS single crystals under driving ac electric field exceeding 10 3 V/cm, have been carried out. These plasma-assisted emission of electrons and ions were examined by means of time and energy distribution measurements. The intensity of registered charges (electrons and ions) displayed on the 2 ms time scale are represented by two distinct peaks. Time dependent energy spectrum of charges, detected under our experimental conditions, involves electrons and ions with maximum energy up to 30–40 eV for first peaks and up to 70–80 eV for second one. Additionally, the energy of electrons is focu…
Hartree–Fock study of adhesion and charge redistribution on the Ag/MgO(0 0 1) interface
2001
Abstract Ab initio study of the Ag/MgO(0 0 1) interfaces based on a quantitative analysis of the bonding in the interfacial region is provided in the framework of Hartree–Fock approach. We are describing the way interfacial electronic and other properties evolve as a function of metal coverage. General conclusion that could be drawn from our calculations is that chemical bond formation is not important for the Ag/MgO(0 0 1) perfect interface. Physisorption of Ag atoms over surface O 2− ions associated with atomic polarization and charge redistribution in the metal planes are the dominant effects. The adhesion energy is enhanced by the interaction of the substrate Mg 2+ ions with the surplus…
Folding and dimerization of resorcarene tetrasulfonates
2001
In the solid state and in CDCl3 resorcarene tetramesitylsulfonates fold by intramolecular SO⋯H–O hydrogen bonds and dimerise via intermolecular O–H⋯OH hydrogen bonding.
Intense laser effects on donor impurity in a cylindrical single and vertically coupled quantum dots under combined effects of hydrostatic pressure an…
2010
WOS: 000280235800010