Hamaker constant

Hamaker constant

The Hamaker constant A can be defined for a van der Waals (vdW) body-body interaction::A=pi^2 imes C imes ho_1 imes ho_2where ho_1 and ho_2 are the number of atoms per unit volume in two interacting bodies and C is the coefficient in the particle-particle pair interaction. [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 ]

The Hamaker constant provides the means to determine the interaction parameter C from the van der Waals (vdW) pair potential, w(r)=-C/r^6.

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/r^6; this is called the retarded regime.

ee also

*Hamaker theory
*van der Waals Forces
*Intermolecular forces

References


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