Atomic and Molecular Properties of Metals from Artificial Cloud Experiments in the Upper Atmosphere

Abstract

Time and frequency resolved observations of metal vapor clouds in the upper atmosphere can be used to obtain information on atomic and molecular properties of the metals involved, e. g. atomic transition probabilities, photoionization cross sections, chemical reactivity of atoms in the ground state and in excited states. Experimental techniques of evaporation, the methods of obser­vation and some of the more important results are discussed for Sr, Ba and Eu, in particular those which cannot be derived by laboratory experiment, namely, radiative transitions and oxidation pro­cesses which involve metastable states. Especially one finds that the photoionization and oxidation processes of Eu and Ba are significantly different in contrast to theoretical predictions