ORCID Profile
0000-0003-1156-5675
Current Organisation
Max-Planck Institute for Chemical Energy Conversion
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Publisher: American Chemical Society (ACS)
Date: 07-01-2016
Publisher: American Chemical Society (ACS)
Date: 08-02-2021
DOI: 10.26434/CHEMRXIV.13725904.V1
Abstract: Vibronic coupling, the interaction between molecular vibrations and electronic states, is a pervasive effect that profoundly affects chemical processes. In the case of molecular magnetic materials, vibronic, or spin-phonon, coupling leads to magnetic relaxation, which equates to loss of magnetic memory and loss of phase coherence in molecular magnets and qubits, respectively. The study of vibronic coupling is challenging, and most experimental evidence is indirect. Here we employ far-infrared magnetospectroscopy to probe vibronic transitions in a Yb III molecular qubit directly. We find intense signals near electronic states, which we show arise due to an “envelope effect” in the vibronic coupling Hamiltonian, and we calculate the vibronic coupling fully ab initio to simulate the spectra. We subsequently show that vibronic coupling is strongest for vibrational modes that simultaneously distort the first coordination sphere and break the C 3 symmetry of the molecule. With this knowledge, vibrational modes could be identified and engineered to shift their energy towards or away from particular electronic states to alter their impact. Hence, these findings provide new insights towards developing general guidelines for the control of vibronic coupling in molecules.
Publisher: American Chemical Society (ACS)
Date: 10-10-2019
DOI: 10.1021/ACS.INORGCHEM.9B02348
Abstract: Ferric hangman porphyrins are bioinspired models for haem hydroperoxidase enzymes featuring an acid/base group in close vicinity to the metal center, which results in improved catalytic activity for reactions requiring O-O bond activation. These functional biomimics are examined herein with a combination of EPR techniques to determine the effects of the hanging group on the electronics of the ferric center. These results are compared to those for ferric octaethylporphyrin chloride [Fe(OEP)Cl], tetramesitylporphyrin chloride [Fe(TMP)Cl], and the pentafluorophenyl derivative [Fe(TPFPP)Cl], which were also examined herein to study the electronic effects of various substituents. Frequency-domain Fourier-transform THz-EPR combined with field domain EPR in a broad frequency range from 9.5 to 629 GHz allowed the determination of zero-field splitting parameters, revealing minor rhombicity
Publisher: Royal Society of Chemistry (RSC)
Date: 2019
DOI: 10.1039/C9SC00987F
Abstract: Symmetry control using DABCO generates a large easy-plane magnetic anisotropy with zero rhombic anisotropy.
Location: Germany
Location: Germany
Location: United States of America
No related grants have been discovered for Joscha Nehrkorn.