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Spectral narrowing in coherent rayleigh scattering.
H T Bookey1, M N Shneider, P F Barker
1Physics, School of Engineering and Physical Sciences, Heriot-Watt University, Edinburgh, Scotland EH14 4AS, United Kingdom.
Physical Review Letters
|October 13, 2007
Summary
Intense laser fields narrow the coherent Rayleigh scattering line shape in carbon dioxide (CO(2)) gas. This spectral narrowing indicates molecules become localized in optical potentials, changing scattering behavior.
Area of Science:
- Nonlinear Optics
- Laser-Matter Interactions
- Molecular Spectroscopy
Background:
- Coherent Rayleigh scattering (CRS) is a sensitive probe of molecular dynamics and interactions.
- High-intensity laser fields can induce significant changes in the optical properties of gases.
- Understanding molecular localization in optical potentials is crucial for controlling light-matter interactions.
Purpose of the Study:
- To investigate the effect of intense laser fields on the CRS line shape in carbon dioxide (CO(2)) gas.
- To explore the transition in scattering mechanisms from untrapped to trapped molecules.
- To analyze the influence of molecular density on spectral broadening.
Main Methods:
- Experimental observation of spectral narrowing in the CRS line shape of CO(2) gas.
- Utilizing intense laser fields in the range of 10(15) W m(-2).
- Varying CO(2) gas densities to study collision effects.
Main Results:
- Observed significant spectral narrowing of the CRS line shape at room temperature.
- The line shape saturates to approximately half its width at low pump intensities.
- At higher densities, collisions between trapped and untrapped molecules lead to spectral broadening.
Conclusions:
- Intense laser fields induce molecular localization in deep optical potentials (60 K).
- A transition occurs from scattering by untrapped molecules to scattering by both trapped and untrapped molecules.
- Collisional effects become significant at higher densities, broadening the spectral profile.
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