Single-shot coherent control of molecular rotation by fs/ns rotational coherent anti-Stokes Raman spectroscopy

We present a novel method, to our knowledge, to control the shape of the spectra using 2-beam hybrid femtosecond (fs)/nanosecond (ns) coherent anti-Stokes Raman scattering (RCARS). The method is demonstrated experimentally and theoretically by utilizing a species-selective excitation approach via a field-free molecular alignment as an illustrative example. Two non-resonant fs laser pulses with proper delay selectively create and then annihilate N-2 resonances in a binary mixture with O-2 molecules. The RCARS signal is simultaneously resolved in spectral and temporal domains within a single-shot acquisition. The method requires very low pulse energies for excitation, hence minimizing multiphoton ionization probability, allowing for coherent control at various temperatures and pressures, with spectroscopic applications in non-stationary and unpredictable reacting flows. Published by Optica Publishing Group under the terms of the Creative Commons Attribution 4.0 License. Further distribution of this work must maintain attribution to the author(s) and the published article's title, journal citation, and DOI.

Automated summary

In this study, a novel method is presented to control the shape of spectra using 2-beam hybrid femtosecond/nanosecond coherent anti-Stokes Raman scattering (RCARS). The method is experimentally and theoretically demonstrated by selectively exciting a species via field-free molecular alignment. The RCARS signal is resolved in both spectral and temporal domains within a single-shot acquisition.