A theoretical study of the photoinduced desorption of I — from a CF3I dimer

Abstract

Ab initio SCF-MO calculations using effective core-potential basis sets are employed to evaluate ionization potentials and electron affinities for CF3I and the geometries and energies of the singlet and triplet states of the CF3I dimer. The calculated geometry of the single state of the dimer is in qualitative agreement with the experimental geometry for condensed phase CF3I. The calculated energy for vertical excitation from the singlet to the triplet state is 4.1 eV at the Hartree-Fock level and 4.5 eV after incorporation of correlation at the Moller-Plesset 2nd-order level, consistent with excitation by 193 nm (6.4 eV) light. The equilibrium geometry of the triplet consists essentially of a CF3I+, CF3I− ion pair, in which the CI bond distance in the anionic component has increased to 5.5Å, compared with 2.1Åin the neutral molecule. The calculated binding energy of the triplet ion pair is about 4 eV.