2023/08/30 by William Barford, Barford, William · 1 citation
Biochemistry, Genetics and Molecular Biology · Medicine · Physics and Astronomy · #Antioxidant Activity and Oxidative Stress #Chemical Physics (physics.chem-ph) #FOS: Physical sciences #Photosynthetic Processes and Mechanisms #Spectroscopy and Quantum Chemical Studies #Strongly Correlated Electrons (cond-mat.str-el)
paper · pdf · doi:10.48550/arxiv.2308.16013
openalex publication_date 2023/08/30 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
A theory of singlet fission (SF) in carotenoid dimers is applied to explain the SF in lycopene H-aggregates observed after high energy photoexcitation. The explanation proposed here is that a high energy, delocalized bright 1Bu+ state first relaxes and localizes onto a single lycopene monomer. The high-energy intramonomer state then undergoes internal conversion to the 11Bu- state. Once populated, the 11Bu- state allows exothermic bimolecular singlet fission, while its internal conversion to the 21Ag- state is symmetry forbidden. The simulation of SF predicts that the intramonomer triplet-pair state undergoes complete population transfer to the intermonomer singlet triplet-pair state within 100 ps. ZFS interactions then begin to partially populate the intermonomer quintet triplet-pair state up to ca. 2 ns, after which hyperfine interactions thermally equilibrate the triplet-pair states, thus forming free, single triplets within ca. 0.1 μs.