Investigation of the local dynamic behavior of atoms and molecules in liquids is crucial for revealing the origin of macroscopic liquid properties. Therefore, direct imaging of single atoms to understand their motions in liquids is desirable. Ionic liquids have been studied for various applications, in which they are used as electrolytes or solvents. However, atomic-scale diffusion and relaxation processes in ionic liquids have never been observed experimentally. We directly observe the motion of individual monatomic ions in an ionic liquid using scanning transmission electron microscopy (STEM) and reveal that the ions diffuse by a cage-jump mechanism. Moreover, we estimate the diffusion coefficient and activation energy for the diffusive jumps from the STEM images, which connect the atomic-scale dynamics to macroscopic liquid properties. Our method is the only available means to observe the motion, reactions, and energy barriers of atoms/molecules in liquids.

中文翻译：

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液体中单个单原子离子的扩散行为和活化能的实空间分析。

研究液体中原子和分子的局部动力学行为对于揭示宏观液体性质的起源至关重要。因此，需要对单个原子进行直接成像以了解其在液体中的运动。已经研究了离子液体在各种应用中的用途，其中离子液体被用作电解质或溶剂。但是，从未通过实验观察到离子液体中原子级的扩散和弛豫过程。我们使用扫描透射电子显微镜（STEM）直接观察离子液体中单个单原子离子的运动，并揭示离子是通过笼跳机制扩散的。此外，我们从STEM图像估计了扩散跳跃的扩散系数和活化能，这些图像将原子尺度的动力学与宏观的液体性质联系起来。