Double-ionization energies of the chloroethane molecules CH 3CH 2Cl, CH 3CHCl 2, CH 3CCl 3, CH 2ClCH 2Cl, CH 2ClCHCl 2, CH 2ClCCl 3, CHCl 2CHCl 2, CHCl 2CCl 3 and CCl 3CCl 3

Abstract

Double-ionization energies of the molecules listed in the title were measured by double-charge-transfer spectroscopy. Since spin is expected to be conserved in double-electron-capture reactions, and OH + was used as the projective ion, the lowest energies measured should correspond to ground triplet states of the dications. Double-ionization energies to these states were calculated using the GAUSSIAN 86 ab initio program package at the Hartree—Fock level with second-order Møller—Plesset perturbation theory. The measured double-ionization energy of CH 3CH 2Cl is 29.8 ± 0.5 eV but the corresponding energies for all the other molecules are lower, lying within ± 0.7 eV of 28.1 eV. A similar pattern is seen in the calculated data. The measured energies are in general higher than those calculated but in all cases by not more than 5%. Double-ionization energies for the fluorine analogues were also calculated and are compared with previously published measured data.