Coherent anti-Stokes Raman spectrometer for THz-frequency modes in biomolecules

A coherent anti-Stokes Raman spectrometer using near-infrared optical parametric oscillators is reported. It scans over a wide frequency range of 0-7000 cm/sup -1/ (0-210 THz). Sensitive detection of THz-frequency vibrational modes of protein in aqueous solution is successfully achieved.