title: Surface layering and melting in an ionic liquid studied by resonant soft X-ray reflectivity.
abstract: The molecular-scale structure of the ionic liquid [C18mim](+)[FAP](-) near its free surface was studied by complementary methods. X-ray absorption spectroscopy and resonant soft X-ray reflectivity revealed a depth-decaying near-surface layering. Element-specific interfacial profiles were extracted with submolecular resolution from energy-dependent soft X-ray reflectivity data. Temperature-dependent hard X-ray reflectivity, small- and wide-angle X-ray scattering, and infrared spectroscopy uncovered an intriguing melting mechanism for the layered region, where alkyl chain melting drove a negative thermal expansion of the surface layer spacing.
authors: Max-Planck-Institut für Polymerforschung, 55128 Mainz, Germany. mezger@mpip-mainz.mpg.de
authors: Markus
authors: M
authors: Mezger
authors: Benjamin M
authors: BM
authors: Ocko
authors: Harald
authors: H
authors: Reichert
authors: Moshe
authors: M
authors: Deutsch