Exploring the Vibrational Side of Spin‐Phonon Coupling in Single‐Molecule Magnets via 161Dy Nuclear Resonance Vibrational Spectroscopy

Bad vibrations? ${}^{161}$Dy nuclear resonance vibrational spectroscopy gives direct experimental access to the partial phonon density of states which includes all vibrational modes involving a displacement of the Dy${}^{III}$ ion. In combination with density functional theory, an assignment to all intramolecular vibrational modes is possible, paving an ideal path to help to clarify the role of phonons in single-molecule magnets.

Synchrotron-based nuclear resonance vibrational spectroscopy (NRVS) using the Mössbauer isotope ${}^{161}$Dy has been employed for the first time to study the vibrational properties of a single-molecule magnet (SMM) incorporating Dy${}^{III}$, namely [Dy(Cy${}_3$PO)${}_2$(H${}_2$O)${}_5$]Br${}_3$⋅2 (Cy${}_3$PO)⋅2 H${}_2$O ⋅2 EtOH. The experimental partial phonon density of states (pDOS), which includes all vibrational modes involving a displacement of the DyIII ion, was reproduced by means of simulations using density functional theory (DFT), enabling the assignment of all intramolecular vibrational modes. This study proves that ${}^{161}$Dy NRVS is a powerful experimental tool with significant potential to help to clarify the role of phonons in SMMs.