Chirality of citronelloxy-cyanobiphenyl monolayer at the air–water interface investigated by the second harmonic generation measurement

Chiral properties of S- and R-enantiomers of citronelloxy-cyanobiphenyl (CCB) monolayer were investigated using dichroic measurement of the optical second harmonic generation (SHG). Using right- and left-circular polarized light, SHG circular dichroism (CD) measurement was performed for LB films of these CCB molecules deposited on silica substrates. For the monolayer at the air–water interface, polarized angle dependence measurement was employed at fixed molecular area. These experiments clearly showed the presence of the chirality in the CCB monolayers. Although the p–s SH signal was monitored to investigate the chiral formation process during monolayer compression, the significant SH signal was not observed, indicating the small chiral components in the nonlinear optical susceptibilities of the CCB molecule.