A comparative study of organic molecular vibrational dynamics by folded box-CARS spectroscopy

This paper reported a comparative study of molecular vibrational dynamics in different organic molecules by femtosecond time-resolved folded box-coherent anti-Stokes Raman scattering (TR-box-CARS) spectroscopy. As model system methanol and ethanol molecules are chosen, the coherence transfer between stretching vibration modes of C-H bonds in them are excited and detected at the same time. Different vibration periods and wavenumber spacing are found for the amplitudes of the coherent vibrations of C-H stretch modes in methanol and ethanol molecules. This study makes femtosecond TR-box-CARS possible as a prospective technique for detection and identification of organic molecular species in ambient environments. A simple spatial magic filter and frequency domain filter method with folded TR-box-CARS approach of suppressing the non-resonant FWM background is demonstrated. • A simple spatial magic filter and frequency domain filter method with folded TR-box-CARS approach of suppressing the non-resonant FWM background is demonstrated. • The coherent Raman modes of C-H stretch modes in different molecules were excited selectively and investigated simultaneously without tuning the laser frequencies due to the large spectral of the preparation pulses. • The obtained oscillations periods of the excited Raman modes, the wavenumber difference, and the decay times for the amplitudes of the Raman modes of C-H stretching vibrations are discussed and simply compared. • This work makes femtosecond TR-box-CARS spectroscopy possible as a prospective technique for detection and identification of organic molecular species in ambient environments by monitoring the coherent Raman modes of C-H bonds in different organic molecules.