Despite a diverse manifold of excited states available, it is generally accepted that the photoinduced reactivity of charge-transfer chromophores involves only the lowest-energy excited state. Shining a visible-light laser pulse on an aqueous solution of the chromophore-quencher [Ru(tpy)(bpy)(μNC)Os^III(CN)₅]⁻ assembly (tpy = 2,2′;6,2''-terpyridine and bpy = 2,2′-bipyridine), we prepared a mixture of two charge-transfer excited states with different wave-function symmetry. We were able to follow, in real time, how these states undergo separate electron-transfer reaction pathways. As a consequence, their lifetimes differ in 3 orders of magnitude. Implicit are energy barriers high enough to prevent internal conversion within early excited-state populations, shaping isolated electron-transfer channels in the excited-state potential energy surface. This is relevant not only for supramolecular donor/acceptor chemistry with restricted donor/acceptor relative orientations. These energy barriers provide a means to avoid chemical potential dissipation upon light absorption in any molecular energy conversion scheme, and our observations invite to explore wave-function symmetry-based strategies to engineer these barriers.

中文翻译：

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电荷转移发色团内电子转移途径的波函数对称控制。

尽管存在多种多样的激发态，但通常认为电荷转移生色团的光诱导反应仅涉及最低能量的激发态。对发色团-淬灭剂的水溶液闪亮的可见光激光脉冲的[Ru（TPY）（联吡啶）（μNC）锇^III（CN）₅ ] ^-通过组装（tpy = 2,2'; 6,2''-吡啶和bpy = 2,2'-联吡啶），我们制备了两种具有不同波函数对称性的电荷转移激发态的混合物。我们能够实时跟踪这些状态如何经历单独的电子转移反应路径。结果，它们的寿命相差三个数量级。隐含的能量垒足够高，可以阻止早期激发态种群内部的转换，从而在激发态势能表面形成孤立的电子传输通道。这不仅与供体/受体相对取向受到限制的超分子供体/受体化学有关。这些能垒提供了一种在任何分子能转换方案中避免光吸收时化学势耗散的方法，