A fountain of droplets

A vessel is plunged upside down into a pool of 50 cSt silicone oil. An air bell is then created. This bell is vertically shaken at 60 Hz that leads to the oscillation of the air/oil interface. The edges of the immersed vessel generate surface waves that propagate towards the center of the bell. When the amplitude of the oscillation increases, wave amplitude increases. We study the influence of the angle between successive sides on the wave patterns. Two kinds of vessel have been studied: a triangular and a square prism. The shape of the air/oil meniscus depends on the angle between the sides of the considered prism. As the amplitude of the oscillation is increased, the triple line, which is the contact line between the solid and the air/oil interface, moves up and down. Above a given acceleration that depends on the immersion depth and on the shape vessel, wave goes under the corner edge of the bell. During the oscillation, the wave generates at the edges presents a singularity that leads eventually to a jet and a drop ejection. A drop is ejected at each oscillation. More complicated ejection can be produced with further increase of the amplitude. This is a sample arXiv article illustrating the use of fluid dynamics videos.Comment: 3 pages, 2 figures, 2 movies (high-res and low-res

XPS and NRA depth profiling of nitrogen and carbon simultaneously implanted into copper to synthesize C₃N₄ like compounds

Carbon nitride nano-compounds have been synthesized into copper by simultaneous high fluence (10 at. cm) implantation of C and N ions. The implantations were performed with a 2 MV Tandem accelerator. The terminal voltage was fixed at 400 kV and the target temperature was maintained at 250 °C during the process. Depth profiling of C and N has been performed using (d,p) and (d,α) nuclear reactions induced by a 1.05 MeV deuteron beam. The retained dose deduced from NRA measurement is relatively close to the implanted one, which indicates that carbon and nitrogen diffusion processes were likely limited during implantation. The chemical bonds between carbon and nitrogen were studied as a function of depth by X-ray photoelectron spectroscopy (XPS). The C 1s and N 1s core level photoelectron spectra revealed the presence of different types of C-N bonds, which correspond to specific kinds of chemical states. These results indicate that different carbon nitride compounds have been formed during the implantation. © 2009 Elsevier B.V. All rights reserved

Titanium oxynitride thin films sputter deposited by the reactive gas pulsing process

International audienc