Cosmic-ray sputtering of interstellar ices in the electronic regime

A compendium of selected literature yields

¹ Institut des Sciences Moléculaires d’Orsay (ISMO), UMR8214, CNRS, Université Paris-Saclay, Bât 520, Rue André Rivière, 91405 Orsay, France
e-mail: emmanuel.dartois@u-psud.fr
² Laboratoire de physique des deux infinis Irène Joliot-Curie,CNRS-IN2P3, Université Paris-Saclay, 91405 Orsay, France
³ Centre de Recherche sur les Ions, les Matériaux et la Photonique, CIMAP-CIRIL-GANIL, Normandie Université, ENSICAEN, UNICAEN, CEA, CNRS, 14000 Caen, France
⁴ Institut de Minéralogie, de Physique des Matériaux et de Cosmochimie, CNRS, MNHN, Sorbonne Univ., 75005 Paris, France
⁵ Université Grenoble Alpes, IPAG, 38000, Grenoble, France ; CNRS, IPAG, 38000 Grenoble, France

Received: 5 November 2022
Accepted: 20 January 2023

Abstract

Aims. With this article, we aim to provide the sputtering yields for molecular species of potential astrophysical interest and in the electronic regime of interaction characteristic of cosmic rays. We specifically target molecules that are constitutive of interstellar ice mantles.

Methods. We used a compendium of existing data on electronic sputtering to calculate the prefactors leading to the generalisation of the stopping-power-dependent sputtering yield for many species condensing at low temperature. In addition, we present new experimental results to constrain the yield for solid CH₄, C₆, and CH₃CN.

Results. Electronic sputtering is constrained using literature data for H₂, HD, D₂, Ne, N₂, CO, Ar, O₂, Kr, Xe, CO₂, SO₂, NH₃, S, H₂O, D₂O, CH₃OH, Leucine, C₂₀H₁₂, C₂₄H₁₂, and C₆₀. A first-order relation with the sublimation enthalpy is derived, which allows us to predict the sputtering yield within an order of magnitude for most species. The fluctuations around the mean are partly assignable to the differences in resilience towards radiolysis for individual species, and partly to the micro-physics details of the energy transfer to the lattice.