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Single ionization of helium by 102 eV electron impact has been studied by measuring the momentum vectors of all final-state particles, i.e., two electrons and the He+ion, with an advanced reaction microscope. Fully differential cross sections for asymmetric scattering geometry, which have been normalized to an absolute scale, have been obtained covering a large range of emission angles for the emitted low-energy (E? 15 eV) electron and different scattering angles for the fast electron. Strong electron emission out of the projectile scattering plane is confirmed for electron impact, as was observed before for heavy-ion impact ionization. The data are compared with theoretical predictions from a three-Coulomb wavefunction model, first-order and second-order distorted-wave approaches, as well as a convergent close-coupling calculation.

Single ionization of CO2by 6 MeV proton impact has been studied by measuring in coincidence the momentum vectors of the emitted electron and the charged nuclear fragment CO+2, CO+or O+, respectively. The experimental data have been compared with the predictions of a state of the art CDW-EIS (continuum distorted wave-eikonal initial state) calculation for molecular orbitals. A good qualitative agreement is observed even though the vibrational motion of the molecule is not taken into account in the model. The low-energy electron spectra show a rich structure which may be attributed to the presence of molecular excitation channels which undergo radiationless decay, via autoionization and also via predissociation. This interpretation is supported by photoionization studies of CO2.

Highly differential cross sections have been obtained for dissociative single ionization of H2 by 6 MeV proton impact by measuring the momentum vectors of the electron and the H+ fragment in coincidence. The investigation of the momentum balance of the fragments along the projectile beam provided detailed insight into the four-particle dynamics, even though the H atom is not detected. Within the axial recoil approximation, molecular-frame angular distributions of emitted electrons have been determined for molecules oriented perpendicular to the projectile beam. They are compared with the predictions of a CDW-EIS calculation.

Highly differential cross sections have been obtained for dissociative single ionization of H₂ by 6 MeV proton impact by measuring the momentum vectors of the electron and the H⁺ fragment in coincidence. The investigation of the momentum balance of the fragments along the projectile beam provided detailed insight into the four-particle dynamics, even though the H atom is not detected. Within the axial recoil approximation, molecular-frame angular distributions of emitted electrons have been determined for molecules oriented perpendicular to the projectile beam. They are compared with the predictions of a CDW-EIS calculation.

We present the results of a systematic experimental study of dissociation and Coulomb explosion of molecular hydrogen induced by intense ultrashort (7-25 fs) laser pulses. Using coincident recoil-ion momentum spectroscopy we can distinguish the contributions from dissociation and double ionization even if they result in the same kinetic energies of the fragments. The dynamics of all fragmentation channels drastically depends on the pulse duration, and for 7 fs pulses becomes extremely sensitive to the pulse shape.

Highly differential cross sections have been obtained for dissociative single ionization of H2by 6 MeV proton impact by measuring the momentum vectors of the electron and the H+fragment in coincidence. The investigation of the momentum balance of the fragments along the projectile beam provided detailed insight into the four-particle dynamics, even though the H atom is not detected. Within the axial recoil approximation, molecular-frame angular distributions of emitted electrons have been determined for molecules oriented perpendicular to the projectile beam. They are compared with the predictions of a CDW-EIS calculation.