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Cooling an Optically Trapped Ultracold Fermi Gas by Periodical Driving
Published on: March 30, 2017
Communication: Optical cooling of trans-stilbene
S A Kovalenko1, A L Dobryakov, E Pollak
1Department of Chemistry, Humboldt-Universität zu Berlin, Berlin, Germany. skovale@chemie.hu-berlin.de
The Journal of Chemical Physics
|July 5, 2013
Summary
Trans-stilbene molecules in solution exhibit distinct vibrational behaviors. Excitation without excess energy leads to cooling, while high energy excitation results in solvent-mediated cooling, impacting photoreaction rates.
Area of Science:
- Photochemistry
- Molecular Spectroscopy
- Physical Chemistry
Background:
- Trans-stilbene is a key molecule for studying photochemical reactions.
- Vibrational energy relaxation dynamics in solution are crucial for understanding reaction pathways.
Purpose of the Study:
- To investigate the vibrational energy dynamics of trans-stilbene in n-hexane after photoexcitation.
- To elucidate the role of solvent-molecule interactions in vibrational cooling and heating processes.
Main Methods:
- Time-resolved Raman spectroscopy with ~100 fs resolution.
- Excitation of trans-stilbene with varying amounts of excess vibrational energy (0-7000 cm(-1)).
Main Results:
- Molecules excited with high excess energy initially show broad Raman linewidths that narrow over picoseconds due to solvent cooling.
- Molecules excited without excess energy exhibit narrow linewidths that broaden over picoseconds due to solvent heating.
- The nascent excited state population is colder than the solvent when excited without excess energy.
Conclusions:
- Solvent collisions play a significant role in modulating the vibrational energy of photoexcited trans-stilbene.
- Initial vibrational energy in the excited state can influence subsequent photoreaction rates, particularly in non-polar solvents.
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