Vibrational excitation of a hydrogen molecular ion by positronium formation in positron-hydrogen molecule collision

Abstract

Recent experimental observation on the production of ions by positron ionization of through positronium formation by Oak Ridge National Group (private communication) suggests that to obtain , an molecular ion should be in a vibrationally excited state by positronium (Ps) formation in - scattering to overcome the potential barrier to the transmission of a proton to He. Here we calculate vibrational excitation cross sections of from the vibrational ground state of by positronium formation in the - collision process employing the adiabatic nuclei (AN) method. The fixed-nuclei positronium formation amplitude is obtained using the first Born approximation. Our results confirm that it should be possible for the above experiments to proceed through the excited vibrational states of . The effect of the dynamical correlation between the Ps channel and the vibrational motions of the molecules is also discussed and is found to be significant.