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A new room‐temperature electrodeposition technique was devised to synthesize normalSnS thin films on indium tin oxidecoated glass slides. This technique is based on a nonaqueous ethylene glycol bath containing anhydrous SnCl2 and elemental sulfur. Three types of electrosyntheses, namely, potentiostatic, galvanostatic, and pulse modes, are discussed and their relative merits compared. A wide variety of characterization techniques were employed to develop a self‐consistent and complementary picture of the morphology, composition, and photoactivity of the normalSnS thin films. These included scanning electron microscopy, x‐ray diffractometry, electron probe microanalyses, Auger electron spectroscopy, x‐ray photoelectron spectroscopy, optical analyses, and voltammetry. The photoactivity of these films was evaluated using photoelectrochemical techniques. Finally, the dark and photocorrosion behavior of these films are discussed with the aid of Pourbaix diagrams.

We present the observation of an efficient mechanism for positron sticking to surfaces termed here Auger-mediated sticking. In this process the energy associated with the positrons transition from an unbound scattering state to a bound image potential state is coupled to a valence electron which can then have sufficient energy to leave the surface. Compelling evidence for this mechanism is found in a narrow secondary electron peak observed at incident positron kinetic energies well below the electron work function.

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In this Letter we report the first observation of low-energy positron (e*) diffraction (LEPD) from a solid surface, Cu(lll). 1 LEPD offers the possibility of becoming a quantitative tool for the study of surfaces to complement the wellestablished technique of low-energy electron diffraction (LEED)c The change in the sign of the The first observation of low-energy positron diffraction from a solid surface is reported. Slow (20-400-eV) monochromatic positron beams were focused onto a Cu(lll) surface and their elastically scattered distributions detected with a channel electron multiplier. Measurements of the scattered intensity versus angle as a function of incident energy show peaks at the predicted (01) and (02) diffraction angles. Profiles of intensity versus energy at fixed angles exhibit maxima corresponding to the primary Bragg peaks.

We analyzed the columnar solidification of a binary alloy under the influence of an electromagnetic forced convection of various types and investigated the influence of a rotating magnetic field on segregation during directional solidification of Al-Si alloy as well as the influence of a travelling magnetic field on segregation during solidification of Al-Ni alloy through directional solidification experiments and numerical modeling of macrosegregation. The numerical model is capable of predicting fluid flow, heat transfer, solute concentration field, and columnar solidification and takes into account the existence of a mushy zone. Fluid flows are created by both natural convection as well as electromagnetic body forces. Both the experiments and the numerical modeling, which were achieved in axisymmetric geometry, show that the forced-flow configuration changes the segregation pattern. The change is a result of the coupling between the liquid flow and the top of the mushy zone via the pressure distribution along the solidification front. In a forced flow, the pressure difference along the front drives a mush flow that transports the solute within the mushy region. The channel forms at the junction of two meridional vortices in the liquid zone where the fluid leaves the front. The latter phenomenon is observed for both the rotating magnetic field (RMF) and traveling magnetic field (TMF) cases. The liquid enrichment in the segregated channel is strong enough that the local solute concentration may reach the eutectic composition.