Abstract: The non-adiabatic quantum dynamics of four prototypical polycyclic aromatic hydrocarbons (PAHs) exhibiting anti-Kasha emission from the S2 state, i.e. 3,4-benzopyrene, 3,4-benzotetraphene, 1,12-benzoperylene and 2′-methyl-1,2-benzanthracene, has been investigated using the multiconfiguration time-dependent Hartree (MCTDH) method. While setting up a model linear vibronic coupling Hamiltonian, we introduce a novel parameter Image ID:d5cp03865k-t1.gif, which quantifies the energy gap between the Sm state at the Franck–Condon geometry and the Sn/Sm minimum energy crossing point of two diabatic states. This parameter serves as a versatile and easy-to-use tool for selecting the most relevant intrastate vibronic couplings and tuning normal modes Qi. The decay dynamics of the studied PAHs has been simulated following photoexcitation to either the first dark excited state (S1) or the first bright excited state (S2). The simulations reveal the dynamic equilibrium between the S1 and S2 states in the early time regime (up to 3 ps). Due to the exceptionally small S1–S2 energy gap and efficient electron–vibrational coupling between these states, molecules in the S1 state can transiently access the S2 state, sustaining a steady population in S2 that can fluoresce spontaneously in violation of the Kasha rule. These findings highlight the critical role of the interplay of the electronic energy gap and vibronic coupling in the excited-state dynamics of molecular systems exhibiting non-trivial anti-Kasha emission.

Cite: Shekhovtsov N.A. , Bushuev M.B.
Non-adiabatic quantum dynamics of polycyclic aromatic hydrocarbons exhibiting anti-Kasha emission from the S2 state
PCCP: PHYSICAL CHEMISTRY CHEMICAL PHYSICS. 2026. V.28. N2. P.1806-1819. DOI: 10.1039/D5CP03865K WOS Scopus

Dates:

Submitted:	Oct 7, 2025
Accepted:	Dec 15, 2025
Published online:	Dec 16, 2025
Published print:	Jan 14, 2026

Identifiers:

Web of science:	WOS:001644720200001
Scopus:	2-s2.0-105025250840

Citing: Пока нет цитирований

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