Ultrafast photoelectron spectroscopy of photoexcited aqueous ferrioxalate. Issue 44 (8th November 2021)

• Record Type: Journal Article
• Authors: Longetti, L.; Barillot, T. R.; Puppin, M.; Ojeda, J.; Poletto, L.; van Mourik, F.; Arrell, C. A.; Chergui, M.
• Is Part Of: Physical chemistry chemical physics. Volume 23:Issue 44(2021)
• Page Start: 25308
• Page End: 25316
• Publication Date: 2021-11-08
• Subjects: Chemistry, Physical and theoretical -- Periodicals; 541.3
• DOI: 10.1039/d1cp02872c
• Languages: English
• ISSNs: 1463-9076

Abstract

Abstract : The photochemistry of metal–organic compounds in solution is determined by both intra- and inter-molecular relaxation processes after photoexcitation. Abstract : The photochemistry of metal–organic compounds in solution is determined by both intra- and inter-molecular relaxation processes after photoexcitation. Understanding its prime mechanisms is crucial to optimise the reactive paths and control their outcome. Here we investigate the photoinduced dynamics of aqueous ferrioxalate ([Fe III (C2 O4 )3 ] 3− ) upon 263 nm excitation using ultrafast liquid phase photoelectron spectroscopy (PES). The initial step is found to be a ligand-to-metal electron transfer, occuring on a time scale faster than our time resolution (≲30 fs). Furthermore, we observe that about 25% of the initially formed ferrous species population are lost in ∼2 ps. Cast in the contest of previous ultrafast infrared and X-ray spectroscopic studies, we suggest that upon prompt photoreduction of the metal centre, the excited molecules dissociate in <140 fs into the pair of CO2 and [(CO2 )Fe II (C2 O4 )2 ] 3− fragments, with unity quantum yield. About 25% of these pairs geminately recombine in ∼2 ps, due to interaction with the solvent molecules, reforming the ground state of the parent ferric molecule.