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Updated: Jun 11, 2025
08:18
Microscopic Visualization of Porous Nanographenes Synthesized through a Combination of Solution and On-Surface Chemistry
Published on: March 4, 2021
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Visualizing Thermally Activated Conical Intersections Governing Non-Radiative Triplet Decay in a Ni(II)
Saül Garcia-Orrit1, Víctor Vega-Mayoral1, Qiang Chen2
1Madrid Institute for Advanced Studies, IMDEA Nanociencia, c/Faraday 9, Campus de Cantoblanco, Madrid 28049, Spain.
The Journal of Physical Chemistry Letters
|October 7, 2024
Summary
Nickel(II) porphyrin relaxation pathways were studied using variable temperature transient absorption. A competition between slow and fast triplet relaxation pathways was observed, influenced by temperature and conical intersections.
Area of Science:
- Photochemistry
- Materials Science
- Physical Chemistry
Background:
- Open-shell transition metal metalloporphyrins, like Nickel(II) porphyrins, are known for rapid excited-state relaxation.
- Understanding these relaxation mechanisms is crucial for designing molecules for optoelectronic applications.
Purpose of the Study:
- To elucidate the nonradiative relaxation pathways in a nanographene-Ni(II) porphyrin conjugate.
- To investigate the temperature-dependent dynamics of excited-state relaxation.
Main Methods:
- Variable temperature transient absorption spectroscopy.
- Global fit analysis of transient absorption data.
- Investigation of photoexcitation dynamics from the lowest π-π* transition.
Main Results:
- At room temperature, vibrational cooling occurs in 1.6 ps, followed by rapid intersystem crossing.
- Singlet decay to the ground state is limited to a short 20 ps window.
- Low-temperature studies revealed a competition between slow (beyond 1.6 ns) and fast (thermally accessible conical intersection) triplet relaxation pathways.
Conclusions:
- The overall triplet decay rate is governed by the interplay between these competing relaxation pathways.
- This finding is significant for understanding fast relaxation in Ni(II) complexes and related materials.
- The study opens possibilities for applications in energy harvesting and optoelectronics.
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