Lifshitz-van der Waals constant

VlSSER, J, Adv. Colloid Interface Sci. 3 (1972) 331. On Hamaker constants a comparison between Hamaker constants and Lifshitz-van der Waals constants. 

The Lifshitz-van der Waals constant for the interaction between two bodies of materials 1 and 2 separated by a medium 3 is given by... 

Solving Eq. (3.91) for the Lifshitz-van der Waals constant or Hamaker s constant usually is not trivial. Many approximations for its calculation have been proposed for various cases [Landau and Lifshitz, 1960 Hough and White, 1980 Visser, 1989 Israelachvili, 1992]. For materials 1 and 2 interacting through material 3, Hamaker s constant becomes... 

The objections to the Hamaker theory were overcome by Lifshitz and his coworkers [Lifshitz 1956, Dzyaloshinskii 1961] using the bulk optical properties of the interacting bodies. The approach employed by Lifshitz uses the so-called Lifshitz-van der Waals constant h that depends only on the materials involved provided the separation distance is relatively small. Under some conditions the constant h can be related to the Hamaker constant by... 

Lifshitz-van der Waals constants for various materials in contact with similar material in vacuum and in water [Visser 1972]... 

Negative values of the Lifshitz-van der Waals constant are possible. For instance Visser [1988] gives the constant for Si in contact with AljO, in water as -0.78 eV. According to Oliveira [1992] negative values of the constant will produce spontaneous separation. 

Visser J (1972) Hamaker constants, comparison between Hamaker constants and lifshitz-van der Waals constants. Adv Colloid Interface Sd 3 331... 

A is a constant valid for parallel circular contact areas and a is the distance between the contacting surfaces. A can be calculated using the Lifshitz-van der Waals constant has = 10 ° — 10 J) or the Hamaker constant H = 10 — 10 J). 

Table 2-1 Van de Waals forces of attraction Fyjy (in 10" N) between a sphere (radius / ) and a half-space at an adhesional distance of 4 A between the adherents, as a function of Lifshitz-van der Waals constant hco (Krupp,1967)...

The Hamaker constant can be obtained by different methods. In this study, we follow the work of Lifshitz , Krupp, in using the Lifshitz - van der Waals constant O) to calculate the Hamaker constant, arrived at... 

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