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Time-resolved Photophysical Characterization of Triplet-harvesting Organic Compounds at an Oxygen-free Environment Using an iCCD Camera
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Time- and Temperature-Resolved Triplet Dynamics in Tungsten Iodide Clusters.
Philipp Frech1, Wolfgang Leis2, Florian Pachel3
1Institute of Physical and Theoretical Chemistry, University of Tübingen, Auf der Morgenstelle 18, 72076 Tübingen, Germany.
Inorganic Chemistry
|October 6, 2025
Summary
Tungsten iodide clusters show rapid intersystem crossing to triplet states. A relativistic model explains their excited-state dynamics, differing from previous molybdenum cluster studies.
Area of Science:
- Inorganic Chemistry
- Photochemistry
- Materials Science
Background:
- Tungsten iodide clusters are promising materials for photochemical applications.
- Understanding their excited-state dynamics is crucial for designing new functional materials.
Purpose of the Study:
- To investigate the excited-state dynamics of tungsten iodide clusters.
- To explore the deactivation pathways of triplet states.
- To compare the behavior of tungsten clusters with molybdenum clusters.
Main Methods:
- Ultrafast transient absorption spectroscopy (200 fs to 400 μs).
- Temperature-dependent emission spectroscopy (4 K to 340 K).
- Time-dependent density functional theory (TD-DFT) calculations.
Main Results:
- Rapid intersystem crossing (< 6 ps) populates triplet states.
- Triplet states deactivate via emission or bimolecular quenching with oxygen.
- Temperature-dependent emission aligns with a three-sublevel model.
- No experimental splitting of lowest triplet states observed, unlike molybdenum clusters.
- TD-DFT reveals significant excited-state geometrical distortions.
Conclusions:
- A relativistic model with three thermally accessible geometries, each with three triplet sublevels, is proposed.
- Group-theoretical models alone are insufficient to describe the observed dynamics.
- Excited-state distortions play a key role in the photophysics of these tungsten clusters.
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