METAL-ION ADSORPTION TO LANGMUIR-BLODGETT-FILMS MONITORED BY THE OPTICAL WAVE-GUIDE TECHNIQUE

We applied optical waveguide methods to monitor the metal ion adsorpti on to ultrathin organic films. As a metal ion-sensitive material we us ed a polymer with azacrown ether sidegroups which are highly selective to CU2+ cation complexation. Ultrathin films of this material were pr epared by applying the Langmuir-Blodgett technique. When exposing such a multilayer structure to an aqueous Cu2+ ion solution, the effective index of the propagating waveguide mode increases, indicating that th e ions are complexed to the molecules of the ultrathin film structure. The prepared layered structure was sensitive to solutions with a conc entration down to c approximate to 3 X 10(-7) M; the response time was in the range of tau = 20-30 min.