Exploring Ultrafast Photoswitching Pathways in RbMnFe Prussian Blue Analogue

We study by femtosecond optical pump‐probe spectroscopy the photoinduced charge transfer (CT) in the RbMnFe Prussian blue analogue. Previous studies evidenced the local nature of the photoinduced MnIIIFeII → MnIIFeIII process, occurring within less than 1 ps. Here we show experimentally that two pho...

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Bibliographic Details
Published inAngewandte Chemie International Edition Vol. 60; no. 43; pp. 23267 - 23273
Main Authors Azzolina, Giovanni, Tokoro, Hiroko, Imoto, Kenta, Yoshikiyo, Marie, Ohkoshi, Shin‐ichi, Collet, Eric
Format Journal Article
LanguageEnglish
Published Weinheim Wiley Subscription Services, Inc 18.10.2021
Wiley-VCH Verlag
EditionInternational ed. in English
Subjects
Charge transfer
electronic structure
Jahn-Teller effect
Manganese
photochemistry
Photoexcitation
Physics
Pigments
Spectroscopy
spin crossover
time-resolved spectroscopy
time-resolved spectroscopy
spin crossover
photochemistry
charge transfer
electronic structure
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Summary:We study by femtosecond optical pump‐probe spectroscopy the photoinduced charge transfer (CT) in the RbMnFe Prussian blue analogue. Previous studies evidenced the local nature of the photoinduced MnIIIFeII → MnIIFeIII process, occurring within less than 1 ps. Here we show experimentally that two photoswitching pathways exist, depending on the excitation pump wavelength, which is confirmed by band structure calculations. Photoexcitation of α spins corresponds to the Mn(d‐d) band, which drives reverse Jahn–Teller distortion through the population of antibonding Mn‐N orbitals, and induces CT within ≈190 fs. The process launches coherent lattice torsion during the self‐trapping of the CT small‐polaron. Photoexcitation of β spins drives intervalence Fe→Mn CT towards non‐bonding states and results in a slower dynamic. Time‐resolved optical spectroscopy combined to electronic band structure calculations revealed two photoinduced charge‐transfer pathways for RbMnFe Prussian blue analogue. Photoexcitation of α spins couples to reverse Jahn–Teller distortion that induces CT, while photoexcitation of β spins induces Fe→Mn CT, stabilized by a spin transition. Lattice torsion modes play an important role for accommodating local distortions and stabilizing CT.
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ISSN:1433-7851
1521-3773
DOI:10.1002/anie.202106959