[en] Oxygen, an usual impurity of photovoltaic silicon, is known to be detrimental for the electrical performances of this material. In this investigation, solidification experiments are performed in coated silica crucibles in order to study the influence of crucible size, crucible coating, argon flow and crucible material on silicon contamination by oxygen. In order to interpret the results, an analytical, semi-quantitative model is established taking into account two oxygen flows: the contamination flow at the crucible/silicon interface and the evacuation flow at the silicon free surface.

[en] Sonoluminescence (SL) spectroscopy is one of the very few ways to study the plasma formed in solutions submitted to ultrasound. Unfortunately, up to now only very limited emission bands were reported in SL spectra of aqueous solutions, moreover broad and badly resolved. It is shown here that by adding some N₂ and/or CO₂ in Ar, new molecular emissions (CN, N₂ and CO) can be observed and that for some of them rovibronic temperatures can be derived. The paramount importance of Stark broadening in these emissions is underlined, together with the need for data on Stark parameters for molecular emissions. (authors)