Influence of ultrathin water layer on the van der Waals/Casimir force between gold surfaces

Abstract

Influence of ultrathin water layer on the van der Waals/Casimir force between gold surfaces Palasantzas, G.; Svetovoy, V. B.; van Zwol, P. J. Take-down policy If you believe that this document breaches copyright please contact us providing details, and we will remove access to the work immediately and investigate your claim.Downloaded from the University of Groningen/UMCG research database (Pure): http://www.rug.nl/research/portal. For technical reasons the number of authors shown on this cover page is limited to 10 maximum. In this paper we investigate the influence of ultrathin water layer ͑ϳ1 -1.5 nm͒ on the van der Waals/ Casimir force between gold surfaces. Adsorbed water is inevitably present on gold surfaces at ambient conditions as jump-up-to contact during adhesion experiments demonstrate. Calculations based on the Lifshitz theory give very good agreement with the experiment in the absence of any water layer for surface separations d տ 10 nm. However, a layer of thickness h Շ 1.5 nm is allowed by the error margin in force measurements. At shorter separations, d Շ 10 nm, the water layer can have a strong influence as calculations show for flat surfaces. Nonetheless, in reality the influence of surface roughness must also be considered, and it can overshadow any water layer influence at separations comparable to the total sphere-plate rms roughness w shp + w.

Results from electrostatic calibrations for measuring the Casimir force in the cylinder-plane geometry

“…Several recent experiments are also showing that the observation of Casimir or Casimir-Polder forces is less trivial than previously stated, for instance, with regards to the dependence on the optical properties of the substrates [82] and the presence of dielectric layers on the substrates [83]. Theoretical arguments have been recently provided for the nontrivial interplay between thermal fluctuations and geometry [84], thermal, conductivity, and roughness corrections [85,86] and the role of the statistical properties of the conducting surfaces [24].…”

Optimizing atomic resolution of force microscopy in ambient conditions

“…In typical conditions the humidity is so large that several water layers form on any surface. 39,40 The effect of this is a drastic lowering of Q and the dramatic increase of E ts where the tip is close enough to the surface to resolve atoms. This can be seen by the large excitation required in Fig.…”

Variations of the Lifshitz–van der Waals force between metals immersed in liquids

“…This same system was used by Palasantzas et al [29] to explain the Casimir force between metal surfaces when an ultra thin film of water was deposited on their surface.…”