Spectroscopic study of the influence of iodine on metal halide discharges

Abstract

A typical metal halide discharge with iodine as the halide was investigated by monitoring the emission radiation densities of atoms, ions, radicals and molecules. The influence of iodine on the spatial distribution of the excitation temperature and electron density was evaluated. Experimental data were used in conjunction with calculated equilibrium plasma composition to explain the mechanism of formation and excitation of different species in the system. Changes in mass and energy transport and in the main plasma parameters and the resulting excitation conditions can be attributed to the high evaporation rate and chemical reactivity of iodine. A direct spectroscopic method was developed for the determination of trace elements with high ionisation potentials and poor detection limits in the presence of iodine.