Time-resolved vibrational optical activity measurement by the infrared-visible sum-frequency-generation with circularly polarized infrared light

The time-resolved infrared-visible sum-frequency-generation (IV-SFG) process of chiral liquids, when the infrared beam is circularly polarized, was theoretically considered. It was shown that the transient dynamics of the molecular chirality can be measured by using the time-resolved circularly polarized (CP) IV-SFG method when the polarization direction of the detected IV-SFG field is controlled to be perpendicular to the polarization directions of the incident infrared (IR) as well as visible beams. In addition, the circular intensity difference was theoretically considered, and it was illustrated that the circular intensity difference (CID) signal is originated from the interference between the all-electric-dipole allowed polarization and the polarizability-quadrupole-induced polarization.