Abstract

Until recently it has not been possible to study liquid surfaces with vacuum based surface science techniques, because they just evaporate and disappear. However, ionic liquids are precisely what they sound like, liquids composed entirely of ions, where the Coulombic attraction between the ions confers such a high enthalpy of vaporisation that they can exist as liquids at ultra-high vacuum. So these liquids can now be studied by the vast range of surface science techniques developed over the past half century, giving molecular level insights into their nature and behaviour. I will describe some of our work on the interaction of ionic liquids with gold and copper single crystals, and the behaviour of gases dissolved in ionic liquids. Although ionic liquids may appear exotic, they outnumber the ≈ 600 “normal” liquids by at least 100,000×, and with their chemically tuneable properties, they are finding ever-increasing uses in academic and industrial applications.