Hamaker Constant

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The Hamaker constant A can be defined for a van der Waals (vdW) body-body interaction:

A=\pi^2\times C \times \rho_1 \times \rho_2

where ρ1 and ρ2 are the number of atoms per unit volume in two interacting bodies and C is the coefficient in the particle-particle pair interaction.[1]

The Hamaker constant provides the means to determine the interaction parameter C from the van der Waals (vdW) pair potential, w(r) = − C / r6.

Hamaker's method and the associated Hamaker constant ignores the influence of an intervening medium between the two particles of interaction. In the 1950s Lifshitz developed a description of the vdW energy but with consideration of the dielectric properties of this intervening medium (often a continuous phase).

The van der Waals forces are effective only up to several hundred angstroms. When the interactions are too far apart the dispersion potential decays faster than 1 / r6 and thus this is called the retarded regime.

[edit] See also

[edit] References

  1. ^ Seung-woo Lee and Wolfgang M. Sigmund."AFM study of repulsive van der Waals forces between Teflon AF thin film and silica or alumina." Colloids and Surfaces A: Physicochemical and Engineering Aspects. Volume 204, Issues 1-3, 23 May 2002, Pages 43–50
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