Nonradiative Excited-State Decay via Conical Intersection in Graphene Nanostructures |
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Authors: | Shunwei Chen Naeem Ullah Yanling Zhao Prof Ruiqin Zhang |
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Institution: | 1. Department of Physics, City University of Hong Kong, Hong Kong SAR, China;2. Department of Physics, City University of Hong Kong, Hong Kong SAR, China
Shenzhen Research Institute, City University of Hong Kong, Shenzhen, China |
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Abstract: | Chemical groups are known to tune the luminescent efficiencies of graphene-related nanomaterials, but some species, including the epoxide group (?COC?), are suspected to act as emission-quenching sites. Herein, by performing nonadiabatic excited-state dynamics simulations, we reveal a fast (within 300 fs) nonradiative excited-state decay of a graphene epoxide nanostructure from the lowest excited singlet (S1) state to the ground (S0) state via a conical intersection (CI), at which the energy difference between the S1 and S0 states is approximately zero. This CI is induced after breaking one C?O bond at the ?COC? moiety during excited-state structural relaxation. This study ascertains the role of epoxide groups in inducing the nonradiative recombination of the excited electron-hole, providing important insights into the CI-promoted nonradiative de-excitations and the luminescence tuning of relevant materials. In addition, it shows the feasibility of utilizing nonadiabatic excited-state dynamics simulations to investigate the photophysical processes of the excited states of graphene nanomaterials. |
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Keywords: | conical intersection excited-state dynamics graphene nanomaterials optical properties TD-DFT |
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