𝔖 Bobbio Scriptorium
✦   LIBER   ✦

Repulsive van der Waals Forces for Silica and Alumina

✍ Scribed by Seung-woo Lee; Wolfgang M. Sigmund


Publisher
Elsevier Science
Year
2001
Tongue
English
Weight
63 KB
Volume
243
Category
Article
ISSN
0021-9797

No coin nor oath required. For personal study only.

✦ Synopsis


The forces of interaction between a flat polytetrafluoroethylene (PTFE) surface and an Ξ±-alumina or amorphous silica sphere in cyclohexane as a function of distance of separation have been measured using the colloid probe technique in an atomic force microscope in a liquid cell. Repulsive van der Waals forces were predicted for the forces of interaction between PTFE and Ξ±-alumina or silica according to the negative Hamaker constants, which were calculated from the dielectric response functions of materials using the Lifshitz theory. The measured forces fit well to theoretically calculated forces, which include the retardation contribution. The retardation effects are apparent at large distance of separation (>4-5 nm), where the measured forces are weaker than the nonretarded prediction.


πŸ“œ SIMILAR VOLUMES


Van der Waals forces between fused silic
✍ G.C.J. Rouweler πŸ“‚ Article πŸ“… 1971 πŸ› Elsevier Science 🌐 English βš– 236 KB

Direct measurements of Van der W&s forces between a flat plate and a pkneconvex Iens are reported for eeparatfans ranging from 40 to 28Onm. Both the lens and the flat plate were fueed silica. Bvo different lensee are used for the measurements. The f&et one with a radiue of curvature of 119.8 cm was

The Dielectric Function for Water and It
✍ Raymond R. Dagastine; Dennis C. Prieve; Lee R. White πŸ“‚ Article πŸ“… 2000 πŸ› Elsevier Science 🌐 English βš– 107 KB

The dielectric response, (iΞΎ ), for water (which is required in Lifshitz theory to calculate the van der Waals interactions in aqueous systems) is commonly constructed, in the absence of complete spectral data, by fitting a damped-harmonic-oscillator model to absorption data. Two sets of parameters