Some Factors Affecting Action Cross Section for Collisions of the Second Kind between Atoms and Ions

Abstract

Enhancement of spark lines of Ag, Au, Al and Cu in neon and helium arcs.—Experiments are described in which the relative probability of the excitation of terms in the spark spectra of metals by impacts of the second kind with ions of helium and neon was determined as a function of the resonance discrepancy. The enhancement of certain levels excited by collisions of the second kind relative to their excitation in a condensed spark or an arc was taken as a measure of the probability of the excitation in a collision of the second kind. The results show a definite resonance effect but sufficient data have not yet been obtained to determine with certainty an empirical formula. The experiments show that, besides resonance discrepancy, the type of level being excited is an important factor in determining the probability of excitation. For excitation by helium and neon ions, triplet levels are strongly preferred over singlet levels in the case of several metals investigated. This preference is not that sort which is predicted by the Wigner rule.