Chiral vibrational sum frequency generation (VSFG) spectroscopy has attracted much attention as a new tool for studying chirality with high sensitivity. Recently, we have developed heterodyne-detected chiral VSFG (HD-chiral VSFG) spectroscopy for the first time, which enables us to determine the phase of the electric field of a chiral VSFG signal. We show that HD-chiral VSFG spectroscopy is capable of the detection and distinction of chirality even from monolayers. In addition, we have studied fundamental aspects of chiral VSFG such as electronic resonance effects and the spatial origin of the signals by using HD-chiral VSFG spectroscopy. This review introduces the principle of chiral VSFG, HD-chiral VSFG spectrometer we have constructed, and its applications to not only bulk samples but also interfaces including monolayers and thin films.
