Faculty of Science and Technology, Meijo University, Nagoya 468-8502, Japan.
Research & Development Group, Hitachi, Ltd., Hatoyama, Saitama 350-0395, Japan.
Microscopy (Oxf). 2022 Jun 6;71(3):142-151. doi: 10.1093/jmicro/dfac006.
In this study, the spatial counting statistics of free electron beams, which were released via field emission from cold metal and propagated through a vacuum region, were investigated to examine the normal functioning of the counting equipment for electron correlation spectroscopy. The beam electrons were recorded separately according to the locations of individual events as they reached the direct detection transmission Complementary Metal Oxide Semiconductor (CMOS) sensor. We examined the spatial point patterns arising from the locations of the individual events of each primary electron being detected in the case of electrons in a state in which the wave function is constant on the sensor. The quadrat method, which compares the observed frequencies of the number of electron counts in the subsets of the study region with the predicted frequencies from a Poisson distribution, indicates a clustering-type departure from complete spatial randomness. To explore some of the basic principles governing the location of coherent electrons being counted, Ripley's K-function and the corresponding L-function of a stationary spatial point process were used to test the complete spatial randomness from the data. The maximum peak in the average of the L-functions was sensitive only to the mean counts per frame. Thus, clustering of spatial point patterns may result from abnormalities in the direct detection camera. When the interaction of the beam electrons with the sensor is included in the simulation, there is a reasonable match between the average of the L-functions and the experimental curves with the theoretically simulated curves.
在这项研究中，通过冷金属的场发射释放并在真空区域传播的自由电子束的空间计数统计数据被研究，以检查电子相关光谱学的计数设备的正常运行。当到达直接检测传输互补金属氧化物半导体 (CMOS) 传感器的单个事件的位置时，根据单个事件的位置单独记录电子束电子。在传感器上波函数恒定的电子状态下，我们检查了每个初级电子的单个事件的位置产生的空间点模式。方格方法将研究区域子集中的电子计数的观测频率与泊松分布的预测频率进行比较，表明存在从完全空间随机性的聚类型偏离。为了探索一些控制相干电子计数位置的基本原理，使用 Ripley 的 K 函数和稳定空间点过程的相应 L 函数来根据数据检验完全空间随机性。L 函数平均值的最大峰值仅对每个帧的平均计数敏感。因此，空间点模式的聚类可能是由于直接检测相机的异常引起的。当将电子束与传感器的相互作用包括在模拟中时，L 函数的平均值与实验曲线与理论模拟曲线之间存在合理的匹配。
