Optical activity effects in second harmonic generation from anisotropic chiral thin films

Circular-difference effects in second-harmonic generation have been used to study chiral, anisotropic thin films of a helicene derivative. For such sa mples, these effects arise both from the chirality of the film and from its anisotropy. We show theoretically and experimentally that there is a funda mental difference between a circular-difference effect originating from chi rality and anisotropy. A method is described that distinguishes the two con tributions. (C) 2000 American Institute of Physics. [S0021-9606(00)70641-6] .