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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.

SUBMITTER: Mezger M

PROVIDER: S-EPMC3593890 | biostudies-other | 2013 Mar

REPOSITORIES: biostudies-other

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Surface layering and melting in an ionic liquid studied by resonant soft X-ray reflectivity.

Mezger Markus M Ocko Benjamin M BM Reichert Harald H Deutsch Moshe M

Proceedings of the National Academy of Sciences of the United States of America 20130219 10

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 uncover ...[more]

PMID: 23431181

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