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Updated: Jan 15, 2026

Time-resolved Photophysical Characterization of Triplet-harvesting Organic Compounds at an Oxygen-free Environment Using an iCCD Camera
Published on: December 27, 2018
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.
Abstract:
This study comprehensively investigates the excited-state dynamics of two tungsten iodide prototype clusters, [(W6I8)I6]2- and [(W6I8)(TFA)6]2- (TFA = trifluoroacetate), utilizing a combination of ultrafast transient absorption spectroscopy from 200 fs up to 400 μs and temperature-dependent emission spectroscopy from 4 to 340 K. Both clusters exhibit rapid intersystem crossing occurring within 6 ps, populating triplet states that subsequently deactivate through emission or dynamical bimolecular quenching involving molecular oxygen. The temperature-dependent emission behavior aligns well with a group-theoretical spin-sublevel model, indicating three distinct emissive sublevels. However, contrary to previous findings in molybdenum-based clusters, no additional splitting of the lowest triplet states was observed experimentally. Time-dependent density functional theory calculations highlight substantial excited-state geometrical distortions, suggesting limitations in sole group-theoretical descriptions. Instead, we propose a relativistic model with three thermally accessible excited-state geometries, each presenting three triplet sublevels.
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