Needs for Cross Sections in Plasma Chemistry

Abstract

Plasma chemistry is a quite new discipline, widely utilized in the last few years for different technological applications. Plasma chemistry started its life many years ago with the use of electrical arcs for the oxidation of nitrogen to NO. Its life continued for many years on a phenomenological basis: only recently has it achieved a position of true science by mixing methodologies stemming from both chemistry and physics. It is practically impossible to quote all the applications of plasma chemistry: to a first approximation we can distinguish plasma chemistry carried out under equilibrium conditions and under nonequilibrium ones. In the first case one can use thermodynamics for estimating the chemical composition of the medium under study and concepts derived from the kinetic theory of gases for estimating the transport properties of the medium. This approach has been discussed in several papers and applies to plasmas continuously running at atmospheric pressure. On the other hand, in these last years, a large effort has been devoted to the understanding of plasmas under nonequilibrium conditions, i.e., under conditions in which the electron energy distribution functions (eedf) are not Maxwellian, and the distributions among the internal degrees of freedom of molecules are non-Boltzmann. Thesemore » conditions are typically met in plasma technology (plasma etching, plasma deposition, plasma treatment of materials), in gas discharge lasers (IR and excimer lasers), in the production of neutral and negative ion beams, in plasma ecology for the destruction of atmospheric pollutants, and in general in those plasmas in which the molecular component plays an essential role. 177 refs., 18 figs., 1 tab.« less