Desorption of neutrals, cations, and anions from core-excited amorphous solid water

Rémi Dupuy (1) , G. Féraud (1) , M. Bertin (1) , Claire Romanzin (2) , L. Philippe (1) , T. Putaud (1) , X. Michaut (1) , R. Cimino (3) , V. Baglin (4) , J.-H. Fillion (1)

1 LERMA - Laboratoire d'Etude du Rayonnement et de la Matière en Astrophysique et Atmosphères = Laboratory for Studies of Radiation and Matter in Astrophysics and Atmospheres
2 ICP - Institut de Chimie Physique
3 LNF - Laboratori Nazionali di Frascati = National Laboratory of Frascati
4 CERN - European Organization for Nuclear Research

Core-excitation of water ice releases many different molecules and ions in the gas phase. Studying these desorbed species and the underlying mechanisms can provide useful information on the effects of X-ray irradiation in ice. We report a detailed study of the X-ray induced desorption of a number of neutral, cationic and anionic species from amorphous solid water. We discuss the desorption mechanisms, and the relative contributions of Auger and secondary electrons (X-ray induced Electron Stimulated Desorption) and initial excitation (direct desorption) as well as the role of photochemistry. Anions are shown to desorb not just through processes linked with secondary electrons but also through direct dissociation of the core-excited molecule. The desorption spectra of oxygen ions (O + , OH + , H2O + , O − , OH −) give a new perspective on their previously reported very low desorption yields for most types of irradiation of water, showing that they mostly originate from the dissociation of photoproducts such as H2O2.

Domaines: Chimie-Physique [physics.chem-ph]

Rémi Dupuy, G. Féraud, M. Bertin, Claire Romanzin, L. Philippe, et al.. Desorption of neutrals, cations, and anions from core-excited amorphous solid water. Journal of Chemical Physics, 2020, 152 (5), pp.054711. ⟨10.1063/1.5133156⟩. ⟨hal-02510801⟩