Nonadiabatic couplings between several electronic excited states are ubiquitous in many organic chromophores and can significantly influence optical properties. A recent experimental study demonstrated that the proflavine molecule exhibits surprising dual fluorescence in the gas phase, which is suppressed in polar solvent environments. Here, we uncover the origin of this phenomenon by parametrizing a linear-vibronic coupling Hamiltonian from spectral densities of system–bath coupling constructed along molecular dynamics trajectories, fully accounting for interactions with the condensed-phase environment. The finite-temperature absorption, steady-state emission, and time-resolved emission spectra are then computed using powerful, numerically exact tensor network approaches. We find that the dual fluorescence in vacuum is driven by a single well-defined coupling mode but is quenched in solution due to dynamic solvent-driven symmetry breaking that mixes the two low-lying electronic states. We expect the computational framework developed here to be widely applicable to the study of non-Condon effects in complex condensed-phase environments.

中文翻译：

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环境驱动的对称性破缺猝灭了普黄素的双荧光

几种电子激发态之间的非绝热耦合在许多有机发色团中普遍存在，并且可以显着影响光学性质。最近的一项实验研究表明，丙黄素分子在气相中表现出令人惊讶的双荧光，而在极性溶剂环境中这种荧光受到抑制。在这里，我们通过根据沿着分子动力学轨迹构建的系统-浴耦合的谱密度参数化线性振动耦合哈密顿量来揭示这种现象的起源，充分考虑与凝聚相环境的相互作用。然后使用强大的、数值精确的张量网络方法计算有限温度吸收、稳态发射和时间分辨发射光谱。我们发现真空中的双荧光是由单一明确的耦合模式驱动的，但由于动态溶剂驱动的对称性破坏混合了两种低位电子态，因此在溶液中被淬灭。我们期望这里开发的计算框架能够广泛适用于复杂凝聚相环境中非康顿效应的研究。