Rostock 2019 – scientific programme
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MO: Fachverband Molekülphysik
MO 18: Posters 2: Time Resolved Spectroscopy
MO 18.2: Poster
Wednesday, March 13, 2019, 16:15–18:15, S Foyer LLM
Photodynamics of an Iron-based Photosensitizer after Deep-UV Excitation — •Niklas Gessner1, Lion-Luca Stiewe1, Johannes Moll2, Katja Heinze2, and Patrick Nuernberger1 — 1Physikalische Chemie II, Ruhr-Universität Bochum, 44801 Bochum — 2Institute of Inorganic Chemistry and Analytical Chemistry, Johannes Gutenberg University Mainz, 55128 Mainz
Photosensitizers are capable of transferring their energy to adjacent molecules after photoexcitation. However, many compounds used in this way in medicine or photovoltaics are complexes of rare noble metals. In contrast to this, [Fe(cpmp)2]2+ comprises an earth-abundant central iron atom that may significantly reduce costs.
In this contribution, we study its photochemical properties with transient absorption spectroscopy in the ultraviolet, visible and mid-infrared (MIR) after excitation at 280 nm to a highly energetic state. Initially, [Fe(cpmp)2]2+ exhibits dynamics on a timescale of 10 ps associated with vibrational cooling and rapid relaxation to a long-lived excited state which shows an excited-state absorption (ESA) around 320 nm. Subsequently, this ESA, the MIR signatures as well as the ground-state bleach decay with the same untypically short time constant of ≈540 ps. In accordance with related compounds [1,2], the study discloses that [Fe(cpmp)2]2+ belongs to the recently emerging class of iron(II) compounds with a strong ligand field so that the system reaches a long-lived 3MC (metal centered) state.
[1] L. L. Jamula et al., Inorg. Chem. 53, 15-17 (2014).
[2] A. K. C. Mengel et al., Chem. Eur. J. 21, 704-714 (2015).