论文标题
石墨烯光显微镜的第一原理模拟
First-principles simulation of light-ion microscopy of graphene
论文作者
论文摘要
2D材料对缺陷和纳米结构的极端敏感性需要精确的成像技术，以验证原子几何形状中所需的存在和不良特征的存在。氦离子束已成为一种有前途的材料成像工具，比传统或环境扫描电子显微镜的分辨率高达20倍，并且比场深度高10倍。在这里，我们提供了第一原理理论见解，以通过执行独立式石墨烯中10-200 keV光离子的单个影响的实时依赖于时间依赖的密度功能理论模拟来推进原子薄材料的离子光束成像。我们预测，检测从材料背面发出的电子（离子退出的侧面）将导致高达3倍的信号和高达5倍的对比度图像，从而使2D材料尤其是离子光束显微镜的引人注目的目标。我们还发现，在石墨烯中诱导的电荷在亚FS时间尺度上平衡，导致碳晶格中只有轻微的干扰，这些干扰不太可能损坏此处研究的任何光束参数的原子结构。
The extreme sensitivity of 2D materials to defects and nanostructure requires precise imaging techniques to verify presence of desirable and absence of undesirable features in the atomic geometry. Helium-ion beams have emerged as a promising materials imaging tool, achieving up to 20 times higher resolution and 10 times larger depth-of-field than conventional or environmental scanning electron microscopes. Here, we offer first-principles theoretical insights to advance ion-beam imaging of atomically thin materials by performing real-time time-dependent density functional theory simulations of single impacts of 10-200 keV light ions in free-standing graphene. We predict that detecting electrons emitted from the back of the material (the side from which the ion exits) would result in up to 3 times higher signal and up to 5 times higher contrast images, making 2D materials especially compelling targets for ion-beam microscopy. We also find that the charge induced in the graphene equilibrates on a sub-fs time scale, leading to only slight disturbances in the carbon lattice that are unlikely to damage the atomic structure for any of the beam parameters investigated here.
