Three-Body Fragmentation from Single Ionization of Water by Electron Impact: The Role of Satellite States

Abstract

Ionization of water with energy transfers close to the 2a inner valence orbital is accompanied by a fast electronic rearrangement driven by electron relaxation and electron-electron correlations. Quasi-degenerate single vacancy and satellites one-electron-two-vacancies excited states in outer shells are created and leave their fingerprints in the three-body fragmentation pattern. Single vacancy states have been associated with Auger decay and double ionization. Satellite excited states are here convincingly assigned to single ionization. We focus on the H + O + H fragmentation by electron impact taking advantage of the high sensitivity of the delayed extraction time-of-flight technique to uncover kinematic attributes of suprathermal O ions. It is found that the H ejections occur under a large angular rearrangement, in an approximate linear geometry, and leaving the O near at rest, with ∼50% of the O produced in water fragmentation by swift electrons presenting this feature.

Effect of the Surface Roughness of Icy Grains on Molecular Oxygen Chemistry in Molecular Clouds

“…They have also derived an upper limit for oxygen atom kinetic energy of 1 eV, or 12,000 K. Experiments by Frémont et al (2005) have shown the same hydrogen peak at 0.2 eV as Makarov et al (2004), with the addition of the observation of a population of oxygen atoms at 0.15 eV (or 1740 K) that appears starting from 20 eV electron energy. More recently, Ferreira et al (2017) studied the kinetic energy distribution of oxygen fragments originating from the electron impact dissociation of water, yielding an average O + energy of 0.063 eV (or 731 K) at 30 eV collision energy.…”

Nonadiabatic fragmentation of H2O+ and isotopomers. Wave packet propagation using ab initio wavefunctions

“…Also, in Fig. 6, we compare, for a = 1751, the ab initio nonadiabatic couplings (symbols) with the values of the derivatives (solid lines) of the transformation angle g XC [see eqn (2)] obtained with the fitted model (17) and (18), for a few values of y (those corresponding to the dotted lines of Fig. 5).…”

“…Experiments of ref. [15][16][17] have measured the kinetic energy release distributions of the fragments formed after electron impact on water molecules, which shed light on the possible routes leading to the different fragmentation schemes.…”

“…Parametrization used for CI 1 (eqn (12)) and CI 2 (eqn (13),(17) and(18)). The constants are expressed in atomic units…”