Fragmentation ofCH4caused by fast-proton impact

Analysis of electron impact ionization properties of methane

“… Malhi et al [1987], Knudsen et al [1995], and Luna et al [2003] reported partial ionization cross sections by proton impact. The positive ion‐pair formation cross sections by protons have also been investigated in detail by Ben‐Itzhak et al [1993, 1994]. Luna et al [2003] also proposed a decay scheme to explain both electron and proton impact dissociative ionization.…”

Dissociative ionization of the H2O molecule induced by medium-energy singly charged projectiles

“…Assuming that the neutrals carry a negligible fraction of KER [19], this estimation can be extended to ion-pair + neutral breakups, too. For the two ion triplets, where only the KER values are available (at 68 and 95 eV [11]), we relied on the analysis provided in the same work by Werner et al [11] for the relative directions of the fragment momenta.…”

“…The emitted fragments * kovacs.sandor@atomki.mta.hu can be neutral or charged particles in excited or ground states [7]. There are also two-or three-step fragmentation processes [7,10,19] Note that a fragmentation channel is usually characterized by the charge states of the precursor ion and the fragments, without specifying their electronic, vibrational, or rotational states. Accordingly, the same channel notation may be used for a set of subchannels with different kinetic energy release (KER) values.…”

“…For few-atom molecules, it is often only a few tenths of an eV, and the upper limit is around 5 eV. For breakups involving at least two positive ions the region of KER extends up to much higher energies: it is between about 3 and 100 eV [19]. The higher KER for the latter case is due to the Coulomb repulsion between the charged fragments, which increases with the charge state of the transient molecular ion (Coulomb explosion) [11,20].…”

“…The several possible excited states of the precursor molecular ion and the emergent fragments result in a spread of the kinetic energies of the fragments originating from the same dissociation channel. Furthermore, the kinetic energy distribution for a certain fragmentation channel may differ in the case of one-, two-, or three-step processes [7,19]. As a result, the fragment energy spectra are rather complex.…”