Selective long range dispersion forces between large systems

Abstract Two large molecular systems capable of giant dipole vibrations of frequencies ω 1 and ω 2 respectively may exert selective very strong long range forces upon each. The selectivity refers to frequency resonance (ω 1 ≈ ω 2 ). Further conditions are (i) the dielectric constant of the medium between them shows strong dispersion in the relevant frequency region or (ii) coherent vibrations are excited by pumping. The latter is always attractive, the former may be either attractive or repulsive.