Systems of monomolecular layers are separated with molecular precision at defined interfaces. The separation can be geared to take place either at the hydrophobic side of a monolayer or at its hydrophilic side. The separated parts, supported by films of polyvinylalcohol or polystyrene respectively, can be brought in molecular contact with appropriate solid substrates. Separation and achievement of molecular contact have been quantitatively investigated by using Förster transfer from an excited donor layer to an acceptor layer.