IONIZATION OF MOLECULAR-HYDROGEN BY PROTON IMPACT .2. 2-ELECTRON PROCESSES

Cross sections for double ionization and ionization plus excitation of H-2 by high-energy protons are calculated as a function of the orientation of the H-2 internuclear axis. Only the contributions of the double-collision process have been included. The ground state of H-2 is described by Heitler-London-type wave functions, and the molecular orbitals for the excited states of H-2+ are constructed from atomic functions. The results have been compared with the data of Edwards et al. [Phys. Rev. A 42, 1367 (1990); 44, 797 (1991); Nucl. Instrum. Methods Phys. Res. B 53, 472 (1991)] and Ezell et al. [Nucl. Instrum. Methods Phys. Res. B 56/57, 292 (1991)]. The theoretical and measured cross sections have the same magnitude for double ionization. For the excitation of the 2p-sigma(u), 2p-pi(u), and 2s-sigma(g) states, the calculated cross sections are much lower than the measured ones.