Volume 88, Number 3, November 2009
Article Number 36004
Number of page(s) 6
Section Condensed Matter: Structural, Mechanical and Thermal Properties
Published online 13 November 2009
EPL, 88 (2009) 36004
DOI: 10.1209/0295-5075/88/36004

X-ray reflectivity reveals equilibrium density profile of molecular liquid under nanometre confinement

E. Perret1, K. Nygård1, D. K. Satapathy2, T. E. Balmer3, O. Bunk1, M. Heuberger4 and J. F. van der Veen1, 3

1   Paul Scherrer Institut - 5232 Villigen PSI, Switzerland
2   Université Fribourg - 1700 Fribourg, Switzerland
3   ETH Zürich - 8093 Zürich, Switzerland
4   EMPA - 9014 St. Gallen, Switzerland

received 28 September 2009; accepted in final form 23 October 2009; published November 2009
published online 13 November 2009

A silane (tetrakis(trimethylsiloxy)silane) has been confined within a space of a few molecular diameters (9 Å) between two atomically flat opposing mica membranes. The liquid's electron density profile along the confinement direction has been determined by synchrotron X-ray reflectivity for film thicknesses of 8.58 and 11.22 nm. We find the liquid's molecules to be strongly layered at layer distances significantly larger than the effective molecular diameter. The considerable free volume enables the confined liquid to retain its liquid properties.

61.25.Em - Molecular liquids. - X-ray reflectometry (surfaces, interfaces, films).
68.08.-p - Liquid-solid interfaces.

© EPLA 2009