No abstract

International audienceA plasma column ejected directly from solid copper by localized microwaves is studied. The effect stems from an induced hotspot that melts and emits ionized copper vapors as a confined fire column. Nanoparticles of ~20-120 nm size were revealed in the ejected column by in situ small-angle x-ray scattering. Optical spectroscopy confirmed the dominance of copper particles in the plasma column originating directly from the copper substrate. Nano- and macroparticles of copper were verified also by ex situ scanning electron microscopy. The direct conversion of solid metals to nanoparticles is demonstrated and various applications are proposed

A storage ring measurement of the rate coefficient for the production of neutral Ar in e + ArH+ collisions is described. It is found that the recombination rate is too small to measure at low centre-of-mass energies but the combined rate coefficient for dissociative recombination and dissociative excitation increases above 2.5 eV displaying peaks centred at 7.5 eV, 16 and 26 eV. Calculated potential energy curves for the ground and excited states of ArH+ are presented and these aid in the elucidation of the recombination and excitation processes observed at higher energies. The implications for plasma modelling are discussed.