Detection Limits for Time-Resolved Coherent TwoDimensional Vibrational Spectroscopy

Coherent two-dimensional vibrational spectroscopy is performed using doubly vibrationally enhanced four-wave mixing in dilute solutions of carbon disulfide using an ultrafast (<1 ps) laser pulse system. The nonresonant electronic background and singly resonant coherent antiStokes Raman scattering contributions are suppressed by delaying the excitation pulses. With this suppression, we measured detection limits of 8 × 10-5 M CS2 in bromochloromethane.