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Title: Surface roughness and adsorption isotherms of molecularly thin liquid films: An x-ray reflectivity study

Abstract

We present an x-ray reflectivity study of molecularly thin films of liquid isobutane adsorbed on liquid glycerol. The glycerol-isobutane interface serves as a model system to investigate the influence of the substrate adsorbate interactions on both adsorption isotherms and capillary wave fluctuations. The measured surface roughness is smaller than expected from the harmonic approximation of the interaction potential. Expressions for the surface roughness in slightly anharmonic potentials are given and compared to the experimental data. A good agreement between data and theory is achieved.

Authors:
; ;  [1]
  1. Institute of Physics, University of Dortmund, 44221 Dortmund (Germany)
Publication Date:
OSTI Identifier:
20778460
Resource Type:
Journal Article
Resource Relation:
Journal Name: Physical Review. E, Statistical Physics, Plasmas, Fluids, and Related Interdisciplinary Topics; Journal Volume: 72; Journal Issue: 6; Other Information: DOI: 10.1103/PhysRevE.72.061601; (c) 2005 The American Physical Society; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; 2-METHYLPROPANE; ADSORPTION; ADSORPTION ISOTHERMS; CAPILLARIES; EXPERIMENTAL DATA; GLYCEROL; LAYERS; LIQUIDS; REFLECTIVITY; ROUGHNESS; SUBSTRATES; THIN FILMS; X RADIATION

Citation Formats

Paulus, M., Gutt, C., and Tolan, M.. Surface roughness and adsorption isotherms of molecularly thin liquid films: An x-ray reflectivity study. United States: N. p., 2005. Web. doi:10.1103/PHYSREVE.72.0.
Paulus, M., Gutt, C., & Tolan, M.. Surface roughness and adsorption isotherms of molecularly thin liquid films: An x-ray reflectivity study. United States. doi:10.1103/PHYSREVE.72.0.
Paulus, M., Gutt, C., and Tolan, M.. Thu . "Surface roughness and adsorption isotherms of molecularly thin liquid films: An x-ray reflectivity study". United States. doi:10.1103/PHYSREVE.72.0.
@article{osti_20778460,
title = {Surface roughness and adsorption isotherms of molecularly thin liquid films: An x-ray reflectivity study},
author = {Paulus, M. and Gutt, C. and Tolan, M.},
abstractNote = {We present an x-ray reflectivity study of molecularly thin films of liquid isobutane adsorbed on liquid glycerol. The glycerol-isobutane interface serves as a model system to investigate the influence of the substrate adsorbate interactions on both adsorption isotherms and capillary wave fluctuations. The measured surface roughness is smaller than expected from the harmonic approximation of the interaction potential. Expressions for the surface roughness in slightly anharmonic potentials are given and compared to the experimental data. A good agreement between data and theory is achieved.},
doi = {10.1103/PHYSREVE.72.0},
journal = {Physical Review. E, Statistical Physics, Plasmas, Fluids, and Related Interdisciplinary Topics},
number = 6,
volume = 72,
place = {United States},
year = {Thu Dec 15 00:00:00 EST 2005},
month = {Thu Dec 15 00:00:00 EST 2005}
}
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  • We report the direct observation of internal layering in thin ({approximately} 45{endash} 90 {Angstrom} ) liquid films of nearly spherical, nonpolar molecules, tetrakis(2-ethylhexoxy)silane, using synchrotron x-ray reflectivity. The Patterson functions have secondary maxima indicating layer formation, and model-independent fitting to the reflectivity data shows that there are three electron density oscillations near the solid-liquid interface, with a period of {approximately} 10 {Angstrom} (consistent with the molecular dimensions). The oscillation amplitude has a strong inverse dependence on the substrate surface roughness. {copyright} {ital 1999} {ital The American Physical Society}