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Published on: January 10, 2025
Absorption spectroscopy of molecular trimers
Joachim Seibt1, Volker Dehm, Frank Würthner
1Institut für Physikalische Chemie, Am Hubland, 97074 Würzburg, Germany.
The Journal of Chemical Physics
|May 5, 2007
Summary
This study analyzes molecular trimer absorption, revealing how geometry influences spectral bands. Geometric information can be extracted from band intensities, aiding in understanding aggregate structures.
Area of Science:
- Physical Chemistry
- Spectroscopy
- Materials Science
Background:
- Understanding molecular aggregates is crucial for designing advanced materials.
- Excitonic coupling in molecular systems dictates their optical properties.
- Vibrational degrees of freedom significantly impact photoabsorption spectra.
Purpose of the Study:
- To investigate the absorption properties of molecular trimers.
- To model the influence of internal vibrational modes on photoabsorption.
- To correlate spectral band shapes and intensities with molecular geometry and electronic coupling.
Main Methods:
- Development of a theoretical model for molecular trimer absorption.
- Inclusion of a single monomer internal vibrational degree of freedom.
- Analysis of spectral band shapes based on varying electronic coupling strengths and geometries.
- Comparison with experimental data from perylene bisimide aggregates.
Main Results:
- Photoabsorption accesses three excitonically coupled excited electronic states.
- Band shapes are sensitive to electronic coupling strength and molecular geometry.
- Molecular geometry can be quantitatively extracted from spectral band intensities.
- Spectra of monomer, dimer, and trimer systems were successfully compared.
Conclusions:
- The developed model accurately describes molecular trimer absorption.
- Spectral analysis provides a pathway for determining molecular geometry in aggregates.
- This approach is applicable to understanding perylene bisimide aggregate systems and similar organic materials.
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