In this work the roles of the shake-off and knockout processes in the double photoionization of the CH2Cl2 and CH4 molecules have been studied. The probabilities for both mechanisms accompanying valence-shell photoionization have been estimated as a function of incident photon energy using Samson's (1990) and Thomas's (1994) models, respectively. The experimental results are in qualitative accord with the models.

Aromatic Infrared Bands, the footprint of molecules like neutral and ionic Polycyclic Aromatic Hydrocarbons (PAHs), have been observed in several astrophysical environments. We present the experimental results of the photoionization and photodissociation of the methyl-benzene (or toluene) molecule, a basic unit for the methylated PAHs, using synchrotron radiation at C1s resonance, similar to 285 eV (soft X-ray) and time-of-flight mass spectrometry. Absolute photoionization and photodissociation cross sections have been determined. Then the ionization and destruction rates and half-life of the toluene molecule were also obtained for the X-ray photon flux of the pre-planetary nebula CRL 618.

A comparative study for the fragmentation of the CH2Cl2 molecule has been performed for collisions with 0.2-2.0 MeV H+ beam and 12.0-90.0 eV photons using the time-of-flight coincidence technique. As opposed to the photoionization case, the abundances in the mass spectra are not strongly dependent on the proton collision energy. The main observed fragment, in the proton impact case, was associated to the detachment of a chlorine atom. Combing the information from the molecular orbital energies, one estimates their relative contributions to the total ionization of CH2Cl2 by proton impact.

Negative ion beams have been proposed as drivers for inertial confinement fusion (ICF), as high-velocity neutral projectiles produced by photodetachment may efficiently impact and heat up a hydrogen pellet target. Charge-changing cross sections are henceforth needed to estimate the beam attenuation in the residual gases. In this work we analyse cross section measurements for the several electron-loss collision channels of fluorine anions impinging on argon (10-50 keV/u energy range) and producing charge states from Ar + to Ar 4+ . Cross sections for projectile destruction associated to target ionization rise steeply with velocity, displaying a clear energy threshold. This threshold is characteristic of a collision process involving direct interaction between a projectile electron and a target electron.