A recently developed time-resolved coherent anti-Stokes Raman scattering(tr-CARS) technique allows the measurement of vibrational coherences with high frequency differences with the ambient environment.The method is based on the short spatial extension of femtosecond pulses with a broadband tunable nonlinear optical parametric amplifier(NOPA) and an internal time delay between the probe and pump/Stokes pulse pair in the CARS process.The different beat frequencies between Raman modes can be selectively detected as oscillations in the tr-CARS transient signal with the broadband tunable NOPA.In this work,we aim at the Raman C-H stretching vibrations from 2800 cm 1 to 3000 cm 1,within which the different vibrational modes in both ethanol and methanol are selectively excited and simultaneously detected.The high time resolution of the experimental set-up allows one to monitor the vibrational coherence dynamics and to observe the quantum beat phenomena on a terahertz scale.This investigation indicates that the femtosecond tr-CARS technique is a powerful tool for the real-time monitoring and detection of molecular and biological agents,including airborne contaminants such as bacterial spores,viruses and their toxins. A recently developed time-resolved coherent anti-Stokes Raman scattering (tr-CARS) technique allows the measurement of vibrational coherences with high frequency differences with the ambient environment. The method is based on the short spatial extension of femtosecond pulses with a broadband tunable nonlinear optical parametric amplifier (NOPA) and an internal time delay between the probe and pump / Stokes pulse pair in the CARS process. the different beat frequencies between Raman modes can be selectively detected as oscillations in the tr-CARS transient signal with the broadband tunable NOPA .In this work, we aim at the Raman CH stretching vibrations from 2800 cm 1 to 3000 cm 1, within which the different vibrational modes in both ethanol and methanol are selectively excited and simultaneously detected. High time resolution of the experimental set-up allows one to monitor the vibrational coherence dynamics and observe the quantum beat phenomena on a terahertz scale. This investigation indicates that the femtosecond tr-CARS technique is a for tool for the real-time monitoring and detection of molecular and biological agents, including airborne contaminants such as bacterial spores, viruses and their toxins.