Cationic and anionic states of CF, CCl, SiF and SiCl. Some new information derived using translational energy spectroscopy

Abstract

Abstract Translational-energy spectroscopy was applied to collisional-excitation and charge-inversion reactions of CF+, CCl+, SiF+ and SiCl+ in order to gain energetic and bond-length information about the anionic and excited-cationic states of the title molecules. The excitation spectra revealed that the a 3 Π state, known in CCl+ and SiCl+, has a term energy of 4.85 ± 0.15 eV in CF+ and 4.70 ± 0.20 eV in SiF+, while the 11Π state, known in CCl+, is not below the dissociation threshold in CF+, SiF+ and SiCl+. These data, and bond-length estimates for the a 3 Π states, are consistent with documented ab initio predictions except for re of CF + ( a 3 Π) which seems to be larger than 1.21 A. Charge-inversion spectra indicated that beams of monohalide cations formed from the tetrahalides, contained substantial proportions of a 3 Π- state ions, and, in the case of CCl, SiF and SiCl, the broadness of spectral peaks was taken as evidence for the stability of the a 1 Δ- state anion. Adiabatic electron affinities were deduced to be 0.49 ± 0.15 eV, 0.89 ± 0.20 eV, 1.34 ± 0.30 eV and 1.40 ± 0.30 eV for the title molecules, respectively.