Photoionization Study of Chlorine Monofluoride and the Dissociation Energy of Fluorine

Abstract

Mass spectra and photoionization yield curves are obtained for the molecular and atomic ions of chlorine monofluoride. The atomic ions are formed both by ion‐pair and by dissociative ionization processes, although the F⁺ ion formed by the latter process is too weak for quantitative measurements. The ClF⁺ curve exhibits a weak onset at 12.55 eV, ascribed to a hot band. An intense onset at 12.65 eV is ascribed to the (0, 0) transition. The observed thresholds for the Cl⁺ ion support the spectroscopic determination of $\mathrm{D(}\mathrm{ClF}\text{)\hspace{0.17em}=\hspace{0.17em}2.558}\mathrm{eV}$ and, combined with a recent determination of the heat of formation of ClF, support the previously reported photoionization value of $D_0\mathrm{°(}{\mathrm{F}}_2\text{)\hspace{0.17em}=\hspace{0.17em}1.34}\mathrm{eV}$ .