Energetics and Dynamics of Ion-Molecule Reactions at Thermal Energies

Energetics and dynamics of non dissociative charge transfer reactions at thermal energies are discussed in the general framework of state selected ion chemistry. Experimental results including kinetic energy, emission spectra and laser induced fluorescence excitation spectra of the product ions are presented. It is shown that in most cases charge transfer reactions at (near) thermal energies do not proceed via a long distance electron jump. The energy deposited in the product ion is not equal to the recombination energy of the reactant ion, part of this energy being converted into kinetic energy of the products. Vibrational population distributions in the product ions are narrow in diatomics (one or two levels) and Franck-Condon populations have never been observed. In contrast whith symmetric charge tranfer, no simple model can account for the experimental results and trajectory calculations on potential energy surfaces are needed.