Formation of water on silicate surfaces under interstellar conditions

¹ LERMA, UMR 8112 du CNRS, Observatoire de Paris et Université de Cergy Pontoise, 5 mail Gay Lussac, 95000 Cergy Pontoise Cedex, France ;
e-mail: Henda.Chaabouni@obspm.fr
² Dipartimento di Scienze Applicate – Università Parthenope di Napoli Centro Direzionale, Isola C4, 80143 Napoli, Italy

Abstract

We explore experimentally the formation of water molecules from O₂ and D atoms on bare grains composed of amorphous silicates analogous to those in diffuse interstellar clouds. We provide the fractions of D₂O and D₂O₂ molecules formed on the silicate surface held at 10 K from the O₂ + D pathway using RAIRS and TPD techniques. For comparison, we also study the formation of water molecules on surfaces covered with amorphous water ice representing the dense clouds.