Non-linear optical spectroscopy as a novel probe for molecular chirality

Optical second-harmonic generation and sum-frequency generation as novel spectroscopic tools to probe molecular chirality are currently being developed. The latter in particular allows studies of chirality associated with both electronic and vibrational transitions of molecules in isotropic bulk, thin films, and monolayers. We review here the recent theoretical and experimental progress in the field. It is shown theoretically and experimentally that both processes can have monolayer sensitivity to detect chirality in electronic and vibrational transitions and that the sensitivity of the sum-frequency spectroscopy of chirality in vibrational transitions can be greatly enhanced through vibrational-electronic double-resonance. Measurements with short-pulsed lasers provide opportunities for time-resolved in situ studies of chirality.