Emission Spectrum of Molecular Fluorine

Abstract

The emission spectrum of fluorine has been investigated under high resolution in the region 4220‐7510 Å. The spectrum was excited by means of a low‐frequency, high‐voltage discharge in fluorine flowing through a sapphire tube. Rotational analyses have been carried out for 21 bands in this region. Nine of these bands, together with six unanalyzed bands, are attributed to the emission spectrum of F2, primarily to the well‐known orange system, C 1 Σ − B 1 Π. Two bands, however, are assigned to a new system, C 1 Σ − B′ 1 Π. The F2spectrum is particularly characterized by extensive perturbations, affecting linewidths, intensities, and level positions. The data permit the calculation of several molecular constants and the deduction of other probable characteristics of the states involved but leave some important questions about the F2spectrum unanswered. The rotational analyses of the 12 remaining bands was aided by the computer processing of over 2900 sharp emission lines in the region 4220‐5090 Å. These bands are attributed to the A 2 Π − X 2 Π system of F2 +, representing the first observation of the optical emission spectrum of this molecule. Several molecular constants of F2 + are also given.