title: Orientational ordering of ionic liquids near a charged mica surface.
abstract: The self-assembly of ions in room-temperature ionic liquids adsorbed on a mica surface is studied using molecular dynamics simulations. Four liquids from the 1-methyl,n-alkylimidazolium bis(trifluoromethylsulfonyl)imide ([C(n)mim][NTf(2)]) family are investigated, where n ranges between 2 and 8. Cations with ethyl or butyl groups are found to orient with the hydrocarbon tails lying parallel to the surface, while the hexyl and octyl tails of cations are observed to be oriented perpendicular to it. The crossover in the orientational preference matches recent observations of surface forces of these liquids.
authors.affiliation: Chemistry and Physics of Materials Unit, Jawaharlal Nehru Centre for Advanced Scientific Research, Jakkur, Bangalore 560 064, India.
authors.forename: Rajdeep Singh
authors.initials: RS
authors.lastname: Payal
authors.forename: Sundaram
authors.initials: S
authors.lastname: Balasubramanian