Physikingenieurwesen (PHY)
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- 2007 (3) (remove)
The dewetting of liquid filaments in linear grooves of a triangular cross section is studied experimentally and theoretically. Homogeneous filaments of glassy polystyrene (PS) are prepared in triangular grooves in a nonequilibrium state. At elevated temperatures, the molten PS restores its material contact angle with the substrate. Liquid filaments with a convex liquid-vapor interface decay into isolated droplets with a characteristic spacing depending on the wedge geometry, wettability, and filament width. This instability is driven by the interplay of local filament width and Laplace pressure and constitutes a wide class of ID instabilities that also include the Rayleigh -Plateau instability as a special case. Our results show an accurately exponential buildup of the instability, suggesting that fluctuations have a minor influence in our system.
In this paper a novel concept of ablation cell for laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) is presented. Suppression of the turbulence in the flush gas flow in the ablation region reduces the wash-out time of the ablation cell considerably. An ablation chamber which enables ICP-MS pulse duration down to several ten milliseconds has been designed. Dependence of the ICP-MS peak amplitude, width, and shape on the gas flow parameters is studied experimentally for aerosol ablated under laminar and turbulent conditions. Experiments demonstrate that the ICP-MS peak becomes sharper and the amplitude of the signal grows as the turbulence in the ablation cell is suppressed. Furthermore, the possibility of the LA-ICP-MS analysis with a sampling rate of more than 10 Hz has been demonstrated. Express in-depth profiling in the new ablation cell is demonstrated on examples of an Al -Zn multilayer structure and an industrial Mg -Zn coating.