Direct observation of the resonant–non-resonant cross-term contribution to coherent Raman scattering of quasi-continuous-wave noisy light in molecular liquids
✍ Scribed by Darin J. Ulness; Michael J. Stimson; Jason C. Kirkwood; A. C. Albrecht
- Publisher
- John Wiley and Sons
- Year
- 1997
- Tongue
- English
- Weight
- 599 KB
- Volume
- 28
- Category
- Article
- ISSN
- 0377-0486
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✦ Synopsis
The resonant-non-resonant cross-term contribution to the coherent Raman scattering (CRS) signal produced by broadband non-transform limited quasi-cw (noisy) light is directly observed in the form of a spectrogram. The technique is a recently developed time-frequency domain version of CRS using noisy light. Vibrational modes of three (neat) molecular liquids were examined : the C-C stretching mode of acetone, the C-Cl stretching mode of methylene chloride and the "ring breathingÏ mode of cyclohexane. The resonant-non-resonant cross-term is revealed as a striking asymmetry in the observed time-frequency domain spectrogram. This is the analogue of the dispersive resonant-non-resonant cross-term in conventional CRS spectroscopy. However, unlike conventional CRS, noisy light interferometry yields a CRS spectrum that is uncoupled from the linewidth which instead governs the interferometric decay. The ratio of the resonant to non-resonant cross-term contribution can be quantiÐed and, as is well known, a reversible link between absolute Raman cross-sections and absolute non-resonant susceptibility of any chosen molecular liquid can be established.