title: Surface segregation in a binary mixture of ionic liquids: Comparison between high-resolution RBS measurements and moleculardynamics simulations.
abstract: Surface structure of equimolar mixture of 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide ([C2C1Im][Tf2N]) and 1-ethyl-3-methylimidazolium tetrafluoroborate ([C2C1Im][BF4]) is studied using high-resolution Rutherford backscattering spectroscopy (HRBS) and molecular dynamics (MD) simulations. Both HRBS and MD simulations show enrichment of [Tf2N] in the first molecular layer although the degree of enrichment observed by HRBS is more pronounced than that predicted by the MD simulation. In the subsurface region, MD simulation shows a small depletion of [Tf2N] while HRBS shows a small enrichment here. This discrepancy is partially attributed to the artifact of the MD simulations. Since the number of each ion is fixed in a finite-size simulation box, surface enrichment of particular ion results in its artificial depletion in the subsurface region.
authors.affiliation: Department of Micro Engineering, Kyoto University, Kyoto-daigaku-katsura, Nishikyo, Kyoto 615-8540, Japan.
authors.forename: Kaoru
authors.initials: K
authors.lastname: Nakajima
authors.affiliation: Department of Micro Engineering, Kyoto University, Kyoto-daigaku-katsura, Nishikyo, Kyoto 615-8540, Japan.
authors.forename: Shunto
authors.initials: S
authors.lastname: Nakanishi
authors.affiliation: Faculty of Health and Social Studies, University of South Bohemia, České Budějovice, Czech Republic.
authors.forename: Zdeněk
authors.initials: Z
authors.lastname: Chval
authors.affiliation: Laboratory of Aerosols Chemistry and Physics, Institute of Chemical Process Fundamentals of the CAS, v. v. i., 165 02 Prague 6-Suchdol, Czech Republic.
authors.forename: Martin
authors.initials: M
authors.lastname: Lísal
authors.affiliation: Department of Micro Engineering, Kyoto University, Kyoto-daigaku-katsura, Nishikyo, Kyoto 615-8540, Japan.
authors.forename: Kenji
authors.initials: K
authors.lastname: Kimura