Capturing Ultrafast Spin Dynamics in Single-Molecule Magnets Using Femtosecond X-ray Emission Spectroscopy

Achieving ultrafast photomagnetic switching of single-molecule magnets (SMMs) could lead to simultaneous fast and dense data storage devices. To facilitate this, a thorough understanding of the ultrafast dynamics emerging after ultrashort laser pulse excitation is essential. However, the complex nature of these materials means there is a lack of established experimental techniques that can probe the spin dynamics in SMMs. Herein, we perform femtosecond time-resolved Mn K-edge X-ray emission spectroscopy on a Mn(III)-based trinuclear SMM (Mn₃) and the model system Mn(acac)₃. The spectral changes of Mn(acac)₃ are consistent with switching between Jahn-Teller distorted structures expected after photoexcitation. A similar result is observed for Mn₃; however, the Kβ signal also reveals insight into the distribution of spin states populated within 100 fs. The importance of using probes across the electromagnetic spectrum to gain a thorough understanding of the dynamics of exchange-coupled complexes is highlighted.