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Intermolecular conical intersections in molecular aggregates


Conical intersections (CoIns) of multidimensional potential energy surfaces are ubiquitous in nature and control pathways and yields of many photo-initiated intramolecular processes. Such topologies can be potentially involved in the energy transport in aggregated molecules or polymers but are yet to be uncovered. Here, using ultrafast two-dimensional electronic spectroscopy (2DES), we reveal the existence of intermolecular CoIns in molecular aggregates relevant for photovoltaics. Ultrafast, sub-10-fs 2DES tracks the coherent motion of a vibrational wave packet on an optically bright state and its abrupt transition into a dark state via a CoIn after only 40 fs. Non-adiabatic dynamics simulations identify an intermolecular CoIn as the source of these unusual dynamics. Our results indicate that intermolecular CoIns may effectively steer energy pathways in functional nanostructures for optoelectronics.

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Fig. 1: Schematic illustration of wave packet motion through a conical intersection (CoIn) in the potential energy surface V(Q1, Q2, Q3) of an A–D–A oligomer aggregate.
Fig. 2: 2DES probes wave packet motion through an intermolecular conical intersection (CoIn) in a thin film of molecular aggregates.
Fig. 3: Non-adiabatic excited-state molecular dynamics simulations of an A–D–A oligomer dimer.

Data availability

The data that support the findings of this study, large data sets stored in the data repositories of different institutions in different countries, are available from the authors upon reasonable request.

Code availability

The NEXMD code is available at This program is open source under the BSD-3 Licence.


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Financial support provided by the Deutsche Forschungsgemeinschaft (SPP1839, SPP1840, GRK1885: Molecular Basis of Sensory Biology, SFB1372: Magnetoreception and Navigation in Vertebrates, SINOXI FR2833/60-1, RTG-2247: Quantum Mechanical Materials Modelling), the Korea Foundation for International Cooperation of Science and Technology (Global Research Laboratory project, K20815000003) and the German-Israeli Foundation (grant no. 1256) is gratefully acknowledged. This work was performed in part at the Center for Nonlinear Studies and the Center for Integrated Nanotechnology, a US Department of Energy and Office of Basic Energy Sciences user facility. We acknowledge support from the Los Alamos National Laboratory (LANL) Directed Research and Development funds. This research used resources provided by the LANL Institutional Computing Program. S.F.-A. acknowledges CONICET, UNQ, ANPCyT (PICT-2018-02360) for their support. We thank P. Donfack and A. Materny for assistance with the Raman measurement. A.D.S. thanks D. Egorova for helpful discussions.

Author information




A.D.S., P.B. and C.L. initiated this project. D.P., E.M.-O. and P.B. synthesized the materials and prepared the thin films. E.S., X.T.N. and A.D.S. performed the experiments. E.S., A.D.S. and C.L. analysed the data. S.P., C.A.R., E.M., L.G., B.T.N., T.F. and S.T. performed quantum chemical modelling of the molecular structure and optical spectra. L.G., B.T.N., S.F.-A., T.F. and S.T. performed non-adiabatic dynamics simulations. A.D.S. and C.L. wrote the manuscript with important contributions from all authors.

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Correspondence to Antonietta De Sio.

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The authors declare no competing interests.

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Peer review information Nature Nanotechnology thanks Oleg Prezhdo and the other, anonymous, reviewer(s) for their contribution to the peer review of this work.

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Supplementary Text, Figs. 1–15 and references.

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De Sio, A., Sommer, E., Nguyen, X.T. et al. Intermolecular conical intersections in molecular aggregates. Nat. Nanotechnol. 16, 63–68 (2021).

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