Dynamics of the fragmentation of D-2 by fast protons and slow highly charged Xe26+ - art. no. 022712

Using recoil-ion momentum spectroscopy, combined with a multihit detector s ystem, the full momentum vectors of both fragment ions produced by fragment ation of D-2 by fast 50-kV protons and slow (9.56-0.191 keV/u) Xe26+ ions h ave been measured. The data are kinematically complete, and make it possibl e to separate the laboratory momentum of the center of mass of the molecule from the momentum of each fragment in the center-of-mass system of the mol ecule. Using this separation, we find that, for higher collision velocities , the overall reaction can be described as double-electron capture, followe d in a second and separate step by a Coulomb explosion of the doubly charge d D-2 Molecule. For the lowest collision velocities, however, the projectil e remains in the vicinity of the molecule during the fragmentation, and thi s clean separation of steps is lost. The projectile is found to extract int ernal energy from the molecule, thus leading to less energetic fragments in the center-of-mass system of the molecule. This effect causes a distortion in the spherical momentum images, as shown by the two-dimensional momentum distributions in the collision plane. The experimental results are found t o be in good agreement with five-body classical trajectory Monte Carlo calc ulations.