We analyze the quenching mechanism of singlet molecular oxygen (¹O₂) by carotenoids, namely lycopene, β-carotene, astaxanthin, and lutein, by means of quantum dynamics calculations and ab initio calculations. The singlet carotenoid (¹Car) and ¹O₂ molecules can form a weakly bound complex via donation of electron density from the highest occupied molecular orbital (HOMO) of the carotenoid to the π_g* orbitals of ¹O₂. The Dexter-type superexchange via charge transfer states (Car^•+/O₂^•–) governs the ¹O₂ quenching. The Car^•+/O₂^•– states are substantially higher in energy (2–4 eV) than the initial ¹Car/¹O₂ states. The quantum dynamics calculations indicate an ultrafast ¹O₂ quenching on a timescale of subpicosecond owing to the strong electronic couplings in the carotenoid/O₂ complexes. The superexchange mechanism via the Car^•+/O₂^•– states dominates the ¹O₂ quenching, although the direct two-electron coupling can also play a certain role.

中文翻译：

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类胡萝卜素通过超快超交换动力学猝灭单线态氧。

我们通过量子动力学计算和从头算的方法，分析了类胡萝卜素即番茄红素，β-胡萝卜素，虾青素和叶黄素对单线态分子氧（¹ O ₂）的猝灭机理。单线类胡萝卜素（¹汽车）和^1个Ò ₂分子可形成类胡萝卜素的弱结合通过从最高电子密度的捐赠复杂占据分子轨道（HOMO）与π_克的*轨道¹ Ò ₂。通过电荷转移状态（Car ^•+ / O ₂ ^•–）的Dexter型超交换控制¹ O ₂淬火。Car ^•+ / O ₂ ^•–状态的能量（2-4 eV）明显高于初始的¹ Car / ¹ O ₂状态。量子动力学计算表明，由于类胡萝卜素/ O ₂络合物中强大的电子耦合，在亚皮秒级的时间尺度上实现了超快的¹ O ₂猝灭。通过Car ^•+ / O ₂ ^•态形成的超交换机制在¹ O ₂猝灭中起主导作用，尽管直接的双电子耦合也可以起一定的作用。