Photoinduced Excited State Electron Transfer at Liquid/Liquid Interfaces

Several aspects of the photoinduced electron transfer (ET) reaction betweencoumarin 314 (C314) and N,N-dimethylaniline (DMA) at the water/DMA interface areinvestigated by molecular dynamics simulations. New DMA and water/DMA potentialenergy surfaces are developed and used to characterize the neat water/DMA interface.The adsorption free energy, the rotational dynamics and the solvation dynamics of C314at the liquid/liquid interface are investigated and are generally in reasonable agreementwith available experimental data. The solvent free energy curves for the ET reactionbetween excited C314 and DMA molecules are calculated and compared with thosecalculated for a simple point charge model of the solute. It is found that thereorganization free energy is very small when the full molecular description of the soluteis taken into account. An estimate of the ET rate constant is in reasonable agreement withexperiment. Our calculations suggest that the polarity of the surface “reported” by thesolute, as reflected by solvation dynamics and the reorganization free energy, is strongly solute-dependent

Two-dimensional phase transitions of water dipoles at mercury/aqueous solution interfaces

965-967The critical temperatures pertaining to order-disorder transitions of water dipoles at mercury/aqueous solution interfaces are estimated taking into account the hydrogen bonding considerations and surface coordination effects via Gibbs free energies. The computed values are in agreement with the experimental data deduced using Laser-induced temperature jump methods as well as empirical correlations

Electrodeposited Ni/SiC composite coating on graphite for high temperature solar thermal applications

Ni/SiC nanocomposite coatings were electrodeposited on graphite (of different shapes) under galvanostatic condition. The effect of the shape of graphite on the morphological, composition, structural properties of the composite coatings, thermal stability and anti-oxidative behaviour at high temperatures were studied. The major composition of the composite coating is silicon carbide (Si5C3, CSi), nickel silicon (Ni0.92Si0.08) and graphite (C). Porous and fine grain structure is formed with cracks. Uniform distributions of SiC nanoparticle were observed. Circular graphite possessed higher adhesion and thickness of the coatings in comparison with rod and square shaped graphite substrate. Thermal analysis of the coated samples indicates the weight loss of SiC coated graphite as 16.5% (rod), 30% (square), 2.5% (Circular). Uncoated graphite had a weight loss of 32.5%. The thermal oxidation of the coated sample in air is least for circular geometry in comparison to rod and square. Thus SiC coated circular graphite can be utilized for high temperature applications such as solar thermal absorbers. Keywords: SiC, Graphite, High temperature coatings, Solar thermal, Anti-oxidation, Geometr