Charge-exchange mass spectra of CCl4, CHCl3, CH2Cl2, CH3Cl and HCl

Abstract

The absolute cross-sections, (Q), for the charge-exchange between positive ions of known electron recombination energies (eVi) and the neutral molecules CCl₄, CHCl₃, CH₂Cl₂, CH₃Cl and HCl have been determined. The cross-sections are independent of the kinetic energy of the primary ions within the range studied. A plot of Q against eVi for each secondary ion constitutes a charge-exchange mass spectrum (CEMS) from which appearance potentials of the secondary ions have been determined: CCl⁺₃(from CCl₄), 11.75 ± 0.2 eV; CHCl⁺₂(from CHCl₃), 11.5 ± 0.2 eV; CH₂Cl⁺₂(from CH₂Cl₂), 11.3 ± 0.2 eV; CH₂Cl⁺(from CH₂Cl₂), 11.9 ± 0.2 eV. The CEMS are compared with the corresponding photoelectron spectra.