Reprint of "Photoinduced dynamics in an exchange-coupled trinuclear iron cluster"
Abstract
We present a joint experimental and computational study of the trinuclear basic carboxylate iron complex FeIII2FeIIO(CH3CO2)6(H2O)3 , which is a model system for understanding photoinduced ultrafast spin dynamics in magnetic iron-based transition metal oxides. We have carried out femtosecond optical transient absorption spectroscopy of molecules in solution at room-temperature exciting either at 400 or 520 nm and observed a long-lived excited-state absorption (ESA) signal from ca. 400-670 nm. The ESA signal is composed of several broad un-resolved bands at 405, 440 and 530 nm. The decay dynamics are complicated and three exponentials with corresponding decay time constants of τ1 = 360 ± 30 fs, τ2 = 5.3 ± 0.6 ps, τ3 = 65 ± 5 ps and a constant offset (τ4 > 500 ps) were needed to fit the data over the full wavelength range. The data indicate that the lowest excited state is populated within the duration of the excitation pulse (< 120 fs). Highly correlated coupled-cluster calculations can satisfactorily reproduce the experimental vibrational spectrum and highlight the role of the μ3 -oxo bridge connecting the Fe ions to create a highly correlated ground-state and identify the excited state as having a mixture of both charge-transfer and ligand-field/d-orbital characters.
- Publication:
-
Journal of Magnetism and Magnetic Materials
- Pub Date:
- May 2020
- DOI:
- 10.1016/j.jmmm.2020.166704
- Bibcode:
- 2020JMMM..50266704L
- Keywords:
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- Nanomagnetism;
- Molecular magnetism;
- Ultrafast dynamics;
- Iron oxide complexes;
- Quantum chemistry