Molecular layering of the Room Temperature Ionic Liquid [bmpy]+ [FAP]- at a Charged Sapphire Surface

Title

Molecular layering of the Room Temperature Ionic Liquid [bmpy]+ [FAP]- at a Charged Sapphire Surface

Abstract

Room-temperature ionic liquids (RTILs) are promising candidates for a broad range of “green” applications, for which their interaction with solid surfaces plays a crucial role. In this high-energy x-ray reflectivity study, the temperature-dependent structure of an ionic liquid with the tris(pentafluoroethyl) trifluorophos-phate anion in contact with a charged sapphire substrate was investigated with submolecular resolution. The RTIL shows strong interfacial layering, starting with a cation layer at the substrate and decaying exponentially into the bulk liquid. The observed decay length and layering period point to an interfacial ordering mechanism, akin to the charge inversion effect, which is suggested to originate from strong correlations between the unscreened ions. The observed layering is expected to be a generic feature of RTILs at charged interfaces.

Speaker

Sebastian Schramm