A monolayer-based setup for optical amplification.

Signal amplification has been demonstrated with surface-bound electrochromic complexes that can exist in one of two oxidation states (M2+/3+). Reaction of FeCl3 with covalently immobilized Os2+ complexes on glass substrates converts the metal centers from one oxidation state to the other. The formed Fe2+ reduces a series of Ru3+-based monolayers. The absorption of light is coupled with the oxidation state of the complexes and provides the output for the monolayer-based device. The gain of the setup can be controlled by the addition of a Fe2+ chelating ligand.