An assessment of an atmospheric pressure helium microwave plasma produced by a surfatron as an excitation source in atomic emission spectroscopy

A new microwave plasma at atmospheric pressure is described. The plasma is supported by a surface wave excitation structure called “surfatron”. Both argon and helium can be used to sustain the plasma. In this study, helium has been selected. The sample introduction system consists of an ultrasonic nebulizer associated with a dcsolvation system. The analytical performance in terms of detection limits, calibration curves and some interferences have been assessed. Because of the relatively low power and the short residence time the main problem seems to be the atomization process.     

Carbon nanotubes as nanoparticles collector

This communication reports on a new method for the collection of nanoparticles using carbon nanotubes (CNT) as collecting surfaces, by which the problem of agglomeration of nanoparticles can be circumvented. CNT (10–50 nm in diameter, 1–10 μm in length) were grown by thermal CVD at 923 K in a 7 v/v% C₂H₂ in N₂ mixture on electroless nickel-plated copper transmission electron microscopy (TEM) grids and Monel coupons. These samples were then placed downstream of an arc plasma reactor to collect individual copper nanoparticles (5–30 nm in diameter). It was observed that the Cu nanoparticles preferentially adhere onto CNT and that the macro-particles (diameter >1 μm), a usual co-product obtained with metal nanoparticles in the arc plasma synthesis, are not collected. Cu–Ni nanoparticles, a catalyst for CNT growth, were deposited on CNT to grow multibranched CNT. CNT-embedded thin films were produced by re-melting the deposited nanoparticles.