Spectroscopic studies of metal/organic interface by nonlinear optical methods

We report SHG observation from CuttbPc LB films deposited on glass, Al and Au substrates and the spectroscopic investigation of the SHG signal on Al and Au surfaces. The possible mechanisms of the SHG enhancement are increase of the electric field inside the medium due to reflection from the Al interface (quadrupole process) and applying the electrostatic field to the centrosymmetric Pc layer due to the surface potential (dipole process). Taking into account the fact that the susceptibility for the static field tends to be smaller than that for the optical frequency, the electric field of the pulsed laser on the order of 1W V/cm is comparable with the field of the surface potential. In order to separate these possibilities, we investigate the spectroscopic characterization of the SHG for phthalocyanine LB films.