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Published on: May 29, 2018
Electronic and vibrational coherence dynamics in a cyanine dye studied using a few-cycle pulsed laser
Ying Wang1, Takayoshi Kobayashi
1Department of Applied Physics and Chemistry and Institute of Laser Science, University of Electro-communications, 1-5-1 Chofugaoka, Chofu, Tokyo, 182-8585, Japan.
Summary
We measured electronic and vibrational coherence relaxation times in a cyanine dye using a 7.1 fs laser. Specific vibrational modes showed long coherence, explained by coupled vibrational energy conservation, with electronic relaxation at 31 fs.
Area of Science:
- Physical Chemistry
- Spectroscopy
- Quantum Dynamics
Background:
- Understanding coherence dynamics is crucial for designing advanced optical materials.
- Cyanine dyes are important in various photochemical and photophysical applications.
- Excited-state wave packets and vibrational energy flow influence material properties.
Purpose of the Study:
- To determine the electronic and vibrational coherence relaxation times in a specific cyanine dye.
- To investigate the factors contributing to long vibrational coherence in excited states.
- To analyze the dynamics of vibrational modes using ultrafast laser spectroscopy.
Main Methods:
- Ultrafast transient absorption spectroscopy using a 7.1 fs pulsed laser.
- Analysis of coherence decay in both ground and excited electronic states.
- Utilizing negative-time data to extract electronic phase relaxation times.
Main Results:
- Vibrational phase relaxation times ranged from 380 to 680 fs.
- Specific vibrational modes (294, 446, 736 cm(-1)) exhibited prolonged dephasing.
- Electronic phase relaxation time was measured to be 31 ± 1 fs.
- A coupled triplet of vibrational modes was identified as responsible for preserving coherence.
Conclusions:
- The study elucidates the mechanisms of coherence preservation in cyanine dyes.
- Coupled vibrational modes play a significant role in maintaining quantum coherence.
- The findings provide insights into the ultrafast dynamics of organic molecules relevant to optical applications.
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