Orbital Mapping Near Interfaces

界面附近的轨道测绘

• 批准号: 423465915
• 负责人: Professorin Dr. Ute Kaiser
• 金额: --
• 依托单位: Zentrale Einrichtung Elektronenmikroskopie
• 依托单位国家: 德国
• 项目类别: Research Grants
• 财政年份: 2019
• 资助国家: 德国
• 起止时间: 2018-12-31 至 2021-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/423465915?language=en
• 关键词: Orbital; Mapping; Near; Interfaces

According to quantum mechanics, electrons move in so-called orbitals around the atomic nuclei. These orbitals and their interaction with one another give rise to numerous materials properties like, e.g., mechanical stability and adhesion, optical, electrical, and magnetic properties as well as chemical bonding. Therefore, orbitals are of paramount importance for many fields from physics over chemistry and materials science to biology. Despite their central role, it has been difficult to visualize and measure individual orbitals inside of solids so far.In this project, we will combine the two methods of transmission electron microscopy and electron energy loss spectrometry to characterize individual atoms inside selected samples. To that end, the size of the orbitals as well as the required measurement precision pose a significant challenge: they are less than one billionth of a meter in size (about a thousand times smaller than the wavelength of light) and for measuring them, the electron beam has to transfer a very specific amount of energy to the sample. Hence, the measured signal is very weak and noisy. To overcome this challenge, latest-generation instruments will be used to reach ideal imaging conditions. In addition, optimal parameters such as sample thickness, acceleration voltage and energy transfer will be determined both theoretically and experimentally. Moreover, we will investigate the suitability of novel imaging techniques such as wavefunction shaping and differential phase contrast for mapping orbitals.Especially interfaces and defects play an important role for orbital mapping. On the one hand, some conclusions about the direction of orbitals only become possible due to the local changes of the sample in the vicinity of interfaces or defects. On the other hand, they have a huge impact on many practical applications such as the adhesion of protective coatings, the efficiency of electronic devices, or the development of new catalysts. Thus, the novel approaches to orbital mapping that will be developed in this project will not only improve our understanding of orbitals but will also lead to a better applicability of this understanding.

根据量子力学，电子在原子核周围的所谓轨道中运动。这些轨道及其彼此之间的相互作用产生了许多材料特性，例如机械稳定性和粘附性、光学、电学和磁性以及化学键合。因此，轨道对于从物理学到化学、从材料科学到生物学的许多领域都至关重要。尽管它们发挥着核心作用，但到目前为止，很难可视化和测量固体内部的单个轨道。在这个项目中，我们将结合透射电子显微镜和电子能量损失光谱测量两种方法来表征选定样品内的单个原子。为此，轨道的大小以及所需的测量精度提出了重大挑战：它们的大小不到十亿分之一米（大约比光的波长小一千倍），并且为了测量它们，需要电子束必须将非常特定的能量传输到样品。因此，测量到的信号非常微弱且有噪声。为了克服这一挑战，将使用最新一代仪器来达到理想的成像条件。此外，还将通过理论和实验确定样品厚度、加速电压和能量转移等最佳参数。此外，我们将研究波函数整形和微分相位衬等新型成像技术对于轨道映射的适用性。特别是界面和缺陷对于轨道映射起着重要作用。一方面，关于轨道方向的一些结论只有由于界面或缺陷附近样品的局部变化才成为可能。另一方面，它们对许多实际应用产生巨大影响，例如保护涂层的附着力、电子设备的效率或新催化剂的开发。因此，该项目将开发的轨道测绘新方法不仅将提高我们对轨道的理解，而且还将导致这种理解的更好适用性。