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Ultrafast Time-resolved Near-IR Stimulated Raman Measurements of Functional π-conjugate Systems
Published on: February 10, 2020
All-ultraviolet time-resolved coherent anti-Stokes Raman scattering
M Mehendale1, J A Giordmaine, E Gatzogiannis
1Department of Chemistry, Princeton University, New Jersey 08544, USA.
Optics Letters
|January 31, 2006
Summary
We achieved higher efficiency using all-UV coherent anti-Stokes Raman scattering (CARS) in calcite. Time-resolved measurements showed vibrational dephasing time increases with excitation, supporting a phonon depletion model.
Area of Science:
- Spectroscopy
- Nonlinear Optics
- Condensed Matter Physics
Background:
- Coherent anti-Stokes Raman scattering (CARS) is a powerful vibrational spectroscopy technique.
- Previous CARS studies often utilized visible light, limiting efficiency and spectral range.
- Ultraviolet (UV) light offers potential for enhanced CARS performance.
Purpose of the Study:
- To investigate the feasibility and efficiency of all-UV CARS.
- To explore the dynamics of internal vibrations in calcite using time-resolved UV CARS.
- To elucidate the role of phonon interactions in vibrational dephasing.
Main Methods:
- Implementation of all-UV CARS using 250-280 nm pump, Stokes, probe, and anti-Stokes light.
- Utilizing calcite as the sample material.
- Performing time-resolved measurements to study vibrational dephasing.
Main Results:
- Achieved approximately 7x higher CARS efficiency in the UV (250-280 nm) compared to visible light (480-540 nm).
- Observed a lengthening of the dephasing time for 1086 cm(-1) CO3(2-) internal vibrations from 4 to 7 ps.
- Demonstrated a correlation between increased vibrational excitation and longer dephasing times.
Conclusions:
- All-UV CARS provides significantly enhanced efficiency over visible CARS.
- The observed lengthening of dephasing time supports a phonon depletion model for vibrational energy relaxation.
- UV CARS is a promising technique for probing vibrational dynamics in condensed matter.
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