Molecular design controlling high-spin formation

A new paper in Nature Communications* shows how molecular design controls high-spin state formation and demonstrates optical readout of quintet states up to room temperature, opening opportunities for molecular quantum technologies.  This study, led by Dr Jeannine Grüne, uses a combination of optically detected magnetic resonance (ODMR), electron paramagnetic resonance (EPR), and ultrafast spectroscopy to resolve the formation and emission pathways of high-spin states in intramolecular single fission systems.

Single fission is a photophysical process in which a photoexcited singlet state evolves into a pair of spin-correlated triplet excitons.  While quintet states are known to form during this process, their direct participation in light emission (particularly at room temperature) has remained experimentally elusive.

In this work, a series of diphenylhexatriene-based dimers and trimers are investigated to reveal how molecular structure controls spin interactions and high-spin state dynamics.  The results demonstrate quintet-mediated emission across all studied oligomers, with molecular structure governing the generation of quintet and triplet states, and the pathways to delayed emission.

The measurements were carried out at the University of Cambridge, the Centre for Advanced Electron Spin Resonance at the University of Oxford, the Freie Universität Berlin, and the University of Sheffield.  The finding establish quintet states as optically active states at room temperature and provide new insight into structure-spin-optical relationships in molecular systems.

Dr Grüne is now an 1851 Research Fellow in the Department of Materials at the University of Oxford, where she continues to explore molecular systems for quantum communication using zero-field ODMR.  

*'High-spin state dynamics and quintet-mediated emission in intramolecular singlet fission'.