Molecular Vibrational Polariton Dynamics: What Can Polaritons Do?
Molecular Vibrational Polariton Dynamics: What Can Polaritons Do?
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DOI：
10.1021/acs.accounts.2c00796
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发表时间：
2023-04-04
影响因子：
18.3
通讯作者：
Xiong, Wei
中科院分区：
文献类型：
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作者：
Xiong, Wei
当分子振动模与光子模的虚态强耦合时，形成新的分子振动极化激元态，沿着大量的暗库模。当原子轨道形成分子键时，极化激元很像成键和反键分子轨道，而暗模很像非键轨道。由于极化激元状态是半物质半光，其能量从母体状态转移，因此预测极化激元会在热激活条件下改变化学，从而导致称为极化激元化学的令人兴奋的新兴领域，该领域可能会改变化学中的范式。尽管有一些已发表的结果支持这一概念，但极化子化学的化学物理和机制仍然难以捉摸。这一挑战的一个原因是以前的工作不能区分极化激元和暗模式。这种限制使得描述极化激元和暗态对化学的贡献变得困难。然而，这种水平的洞察力是至关重要的发展一个坚实的机制，极化子化学设计和预测的结果，强耦合与任何给定的反应。我的团队解决了通过超快二维红外（2D IR）光谱区分极化激元和暗模式动力学的挑战。具体来说，（1）我们发现极化激元可以促进分子内和分子间的振动能量转移，打开了一条控制液相分子系统中振动能量流动的途径，（2）通过研究单步异构化事件，我们证实了极化激元确实可以在强耦合条件下修改化学动力学，但相反，暗模式表现得像未耦合的分子，并且不改变动力学。这一发现证实了极化激元化学的核心概念：极化激元改变了反应的势能景观。这一结果也阐明了暗模的作用，为未来极化激元化学的腔体设计奠定了重要基础。除了使用二维红外光谱研究极化激元化学，我们还使用相同的技术将分子极化激元开发成潜在的量子模拟平台。我们证明了极化激元具有拉比振荡，并使用棋盘式腔设计，我们表明极化激元可以在整个空间具有很大的非线性。我们进一步用棋盘格极化激元来模拟相干转移并将其可视化，观察到了单向的相干转移，表明非厄米动力学。在这个帐户中突出的努力提供了一个坚实的理解的能力，极化子的化学和量子信息科学。最后，我讨论了一些挑战，使极化子化学朝着可预测的方向发展，并使极化子量子平台成为现有系统的补充。
When molecular vibrational modes strongly couple to virtual states of photonic modes, new molecular vibrational polariton states are formed, along with a large population of dark reservoir modes. The polaritons are much like the bonding and antibonding molecular orbitals when atomic orbitals form molecular bonds, while the dark modes are like nonbonding orbitals. Because the polariton states are half-matter and half-light, whose energy is shifted from the parental states, polaritons are predicted to modify chemistry under thermally activated conditions, leading to an exciting and emerging field known as polariton chemistry that could potentially shift paradigms in chemistry. Despite several published results supporting this concept, the chemical physics and mechanism of polariton chemistry remain elusive. One reason for this challenge is that previous works cannot differentiate polaritons from dark modes. This limitation makes delineating the contributions to chemistry from polaritons and dark states difficult. However, this level of insight is critical for developing a solid mechanism for polariton chemistry to design and predict the outcome of strong coupling with any given reaction. My group addressed the challenge of differentiating the dynamics of polaritons and dark modes by ultrafast two-dimensional infrared (2D IR) spectroscopy. Specifically, (1) we found that polaritons can facilitate intra- and intermolecular vibrational energy transfer, opening a pathway to control vibrational energy flow in liquid-phase molecular systems, and (2) by studying a single-step isomerization event, we verified that indeed polaritons can modify chemical dynamics under strong coupling conditions, but in contrast, the dark modes behave like uncoupled molecules and do not change the dynamics. This finding confirmed the central concept of polariton chemistry: polaritons modify the potential energy landscape of reactions. The result also clarified the role of dark modes, which lays a critical foundation for designing cavities for future polariton chemistry. Aside from using 2D IR spectroscopy to study polariton chemistry, we also used the same technique to develop molecular polaritons into a potential quantum simulation platform. We demonstrated that polaritons have Rabi oscillations, and using a checkerboard cavity design, we showed that polaritons could have large nonlinearity across space. We further used the checkerboard polaritons to simulate coherence transfer and visualize it. A unidirectional coherence transfer was observed, indicating non-Hermitian dynamics. The highlighted efforts in this Account provide a solid understanding of the capability of polaritons for chemistry and quantum information science. I conclude this Account by discussing a few challenges for moving polariton chemistry toward being predictable and making the polariton quantum platform a complement to existing systems.