Validity of Franck-Condon principle for H+to H-double charge transfer of fast protons on H2at low scattering angle

Translational energy spectra of H - ions arising from single and double collision double charge transfer of 4 keV protons on H 2 at small scattering angle have been measured. Comparison of the energy losses corresponding to the observed peaks with the expected values shows that the Franck-Condon principle is obeyed in such collisional transitions.