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Ultrafast Time-resolved Near-IR Stimulated Raman Measurements of Functional π-conjugate Systems
Published on: February 10, 2020
Stimulated Raman effect in some tetrahedral molecules.
D H Rank1, R V Wick, T A Wiggins
1Physics Department, The Pennsylvania State University, University Park, Pennsylvania, USA.
Applied Optics
|January 6, 2010
Summary
Researchers studied stimulated Raman spectra in tin tetrachloride (SnCl4) and methane gas using a ruby laser. Methane showed a sharp spectral line with no pressure shift, while SnCl4 exhibited a single line and its sound velocity was measured.
Area of Science:
- Spectroscopy
- Laser Physics
- Condensed Matter Physics
Background:
- Stimulated Raman spectroscopy (SRS) provides insights into molecular vibrations.
- Understanding spectral line broadening and shifts is crucial for accurate molecular characterization.
- Investigating stimulated Brillouin scattering (SBS) complements SRS studies.
Purpose of the Study:
- To excite and analyze stimulated Raman spectra in liquid SnCl4 and methane gas.
- To determine the vibrational frequency and pressure shift of methane.
- To characterize the spectral features and acoustic properties of SnCl4.
Main Methods:
- Utilizing a medium high-power ruby laser to excite stimulated Raman spectra.
- Employing a high-resolution grating spectrograph for spectral analysis.
- Using a Fabry-Perot etalon to observe stimulated Brillouin scattering.
Main Results:
- Measured methane's vibrational frequency (nu1) as 2916.605 cm(-1) +/- 0.012 cm(-1) with no detectable pressure shift from 3 to 12 amagat.
- Observed sharp, narrow stimulated Raman lines in methane, slightly broader than the laser line.
- SnCl4 showed a single SRS Stokes line (0.5 cm(-1) width), narrower than expected, with stimulated Brillouin scattering also observed.
Conclusions:
- Methane exhibits minimal pressure-induced spectral shifts under the studied conditions.
- The spectral characteristics of SnCl4 suggest complex interactions influencing the stimulated Raman signal.
- The velocity of sound in SnCl4 was determined to be 840 m/s at 27°C via stimulated Brillouin measurements.
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