Indirect interaction of colloidal molecules adsorbed on soft surfaces

Colloidal molecules adsorbed on Langmuir-Blodgett films interact via elasti c substrate deformations. The interaction potential of this indirect force depends on the alteration of the surface profile around the adsorbed molecu les. If an adsorbed particle causes a reduction of the substrate thickness, an attraction force results. Otherwise, if the adsorbate only bends the su rface profile without changing the average film thickness, adsorbed molecul es repel each other. The strength of this repulsion force decreases with in creasing thickness of the Langmuir-Blodgett film. Colloidal molecules incom mensurately adsorbed on the surface of soft crystals behave differently. Fo r large distances their interaction is always attractive.