AI 中文总结
本研究针对电子关联显微镜（ECM）的误差问题，提出了ECM专属的强度归一化框架，经模拟和实验验证，可准确评估纳米时空动力学并纠正旧框架的分类错误。
AI 中文摘要
电子关联显微镜（ECM）可通过强度关联函数测量具有纳米级空间分辨率的材料动力学。然而，在计算强度关联时直接采用X射线光子关联光谱（XPCS）的归一化框架会引入误差。由于纳米束电子衍射中采样体积受限且散斑尺寸更大，XPCS式的时间平均和散射矢量平均会引入系统伪影，如人工反关联或升高的基线，进而导致结构弛豫时间和拉伸指数出现系统误差。本研究提出了受物理原理启发、针对ECM的强度归一化方法，该方法对第一衍射环的时间平均和方位角平均强度进行处理，以限制上述误差。通过CuZr过冷液体的分子动力学模拟验证该框架，将其与自中间散射函数进行基准对比，成功复现了弛豫时间。将该方法应用于Pt57.5Cu14.7Ni5.3P22.5纳米线的实验时间分辨4D STEM数据集时，其正确识别出高度稳定、无变化的纳米级晶相，而这些晶相此前被旧框架错误归类为弛豫畴。基于该发现，本研究重新评估了其他先前的ECM研究。该鲁棒方法为评估局域时空弛豫行为建立了无伪影的途径。
英文摘要
Electron correlation microscopy (ECM) can measure materials dynamics with nanoscale spatial resolution from intensity correlation functions. However, adopting X-ray photon correlation spectroscopy (XPCS) normalization frameworks unchanged when calculating intensity correlations can introduce errors. Due to the constrained sampling volumes and larger speckle sizes in nanobeam electron diffraction, XPCS-style time-averaging and scattering-vector averaging introduce systematic artifacts, such as artificial anticorrelations or elevated baselines that lead to systematic errors in structural relaxation times and stretching exponents. This work presents physics-inspired, ECM-specific intensity normalizations over time- and azimuthal-averaged intensities of the first diffraction ring that limit those errors. The framework is validated using molecular dynamics simulations of a CuZr supercooled liquid to benchmark against the self intermediate scattering function, successfully reproducing relaxation times. When applied to experimental time-resolved 4D STEM datasets of a Pt57.5Cu14.7Ni5.3P22.5 nanowire, the method correctly identifies highly stable, unchanging nanoscale crystalline phases that were erroneously misclassified as relaxing domains by previous frameworks. Other previous ECM research is reevaluated in light of these observation. This robust approach establishes an artifact-free pathway for evaluating localized spatiotemporal relaxation behaviors.
