Relationship between intensity of surface second harmonic generation and molecular structure in helix molecular films

The relationship between intensity of surface Second Harmonic Generation (S HG) and the pitch, radius and azimuthal angle of molecules on the surface o f helix molecular films is analyzed. The values of pitch and radius corresp onding to the maximal intensity of SHG have been shown to exist. The theore tical results are compared with the experimental ones reported by Mohlman e t al., and the limitation of their conclusion is also pointed out.