Optical Projection and Spatial Separation of Spin-Entangled Triplet Pairs from the S<inf>1</inf> (2<sup>1</sup> A<inf>g</inf><sup>–</sup>) State of Pi-Conjugated Systems
MetadataShow full item record
Pandya, R., Gu, Q., Cheminal, A., Chen, R., Booker, E., Soucek, R., Schott, M., et al. (2020). Optical Projection and Spatial Separation of Spin-Entangled Triplet Pairs from the S<inf>1</inf> (2<sup>1</sup> A<inf>g</inf><sup>–</sup>) State of Pi-Conjugated Systems. Chem, 6 (10), 2826-2851. https://doi.org/10.1016/j.chempr.2020.09.011
The S1 (21Ag-) state is an optically dark state of natural and synthetic pi-conjugated materials that can play a critical role in optoelectronic processes such as, energy harvesting, photoprotection and singlet fission. Despite this widespread importance, direct experimental characterisations of the electronic structure of the S1 (21Ag-) wavefunction have remained scarce and uncertain, although advanced theory predicts it to have a rich multi-excitonic character. Here, studying an archetypal polymer, polydiacetylene, and carotenoids, we experimentally demonstrate that S1 (21Ag-) is a superposition state with strong contributions from spin-entangled pairs of triplet excitons (1(TT)). We further show that optical manipulation of the S1 (21Ag-) wavefunction using triplet absorption transitions allows selective projection of the 1(TT) component into a manifold of spatially separated triplet-pairs with lifetimes enhanced by up to one order of magnitude and whose yield is strongly dependent on the level of inter-chromophore coupling. Our results provide a unified picture of 21Ag-states in pi-conjugated materials and open new routes to exploit their dynamics in singlet fission, photobiology and for the generation of entangled (spin-1) particles for molecular quantum technologies.
External DOI: https://doi.org/10.1016/j.chempr.2020.09.011
This record's URL: https://www.repository.cam.ac.uk/handle/1810/315898
Attribution 4.0 International
Licence URL: https://creativecommons.org/licenses/by/4.0/