Center for Relativistic Laser Science

2017 120th KCS Meeting

Stimulated Raman Scattering (SRS) can obtain much enhanced scattering cross section (about seven orders of magnitude) than normal Raman scattering. Conventional SRS uses two-waves, pump and Stokes light, to detect molecular vibrational mode. The previous studies tuned the pump and Stokes wavelength to make vibrational coherence, and obtained vibrational information of molecules. To investigate the interaction between two different SRS processes, we implement a three color SRS experiment which enables to simultaneously induce two different vibrational coherence of two SRS process in the same molecule: the pump and one Stokes light is resonant to a vibrational mode; the pump and another Stokes light is resonant to a different vibrational mode. We observed competitive behavior of two SRS processes, in which one SRS process can suppress another SRS process, for the first time. The depletion phenomenon is induced only when both the two different SRS modes are resonant to Raman transitions. Our experimental results also indicate that SRS depletion is caused by confined amount of pump photons. We obtained up to 62% efficiency of depletion of the ring breathing mode of benzene by using the CH stretching mode for depletion. With these experimental data, we expect this new switching-off concept for SRS has a potential to be practically used in various area, like the study for molecular energy redistribution, etc.

References

[1] Sun, Z.; Qiu, X. Q.; Lu, J.; Zhang, D. H.; Lee, S. Y., Three‐state model for femtosecond broadband stimulated Raman scattering. Journal of Raman Spectroscopy 2008, 39, 1568-1577.

[2] McAnally, M. O.; McMahon, J. M.; Van Duyne, R. P.; Schatz, G. C., Coupled wave equations theory of surface-enhanced femtosecond stimulated Raman scattering. The Journal of Chemical Physics 2016, 145, 094106.

[3] McCamant, D. W.; Kukura, P.; Yoon, S.; Mathies, R. A., Femtosecond broadband stimulated Raman spectroscopy: Apparatus and methods. Review of Scientific Instruments 2004, 75, 4971-4980.