2ND-HARMONIC GENERATION CIRCULAR-DICHROISM SPECTROSCOPY FROM CHIRAL MONOLAYERS

The second-harmonic-generation (SHG) efficiency from a monolayer of or iented chiral molecules (R- or S-2,2'-dihydroxyl-1,1'binaphthyl) has a strong dependence upon the handedness of the circularly polarized exc itation beam. The SHG circular-dichroism (CD) effect is much larger th an in ordinary CD spectroscopy because SHG-CD is electric dipole allow ed. The technique allows the study of chiral surfaces. The preference for left or right circularly polarized light is dependent on both the chirality (R or S) and the absolute orientation of the molecules (poin ted up or down).