Development of a new method of electric/magnetic-filed measurementin a transmission electron microscope

在透射电子显微镜（TEM）中，通常使用两种公知的方法来观察电场/磁场分布。第一种是电子全息术，它需要一个非常昂贵的场发射枪TEM（FEG TEM）。另一种是洛伦兹显微术，虽然洛伦兹显微术可以在常规的透射电子显微镜中进行，但菲涅耳模式的像是在离焦条件下获得的，而傅科模式的像不适合于定量分析。在原位电子全息实验中，我们发现在很低放大率模式（称为“低Mag”模式）下，选择区衍射（SAD）孔径的像会发生畸变，同时施加一个外部的静电电位的标本使用几何光学分析这种现象表明，图像的失真可以相关的偏转的电子束的静电场在一个样品的水平。这种方法可以应用于 ...更多信息 分析了常规TEM中由于电场引起的阴影像畸变的几何电子光学，确定了系统中物镜透镜和中间透镜以及聚光透镜的场强估算光学参数。计算了沿着电子束通道的静电势分布，并与实测值进行了比较。结果表明，该方法可以定量地测量静电场水平分量的积分，并将其应用于某些真实的材料中，如在试样位置上用半切割的铜网片固定在电极上，观察到了静电场水平分量的积分。在有和没有导电碳膜的圆形孔中观察到了显示局部场分布差异的二维图，导电碳膜使孔中的场归一化。栅状光阑阴影像的整体位移对应于试件上部的场强，建议分别检测试件位置和试件上下部的局部场分布。通过我们的研究，我们采用了几种将电极安装在透射电子显微镜侧面进入保持器上的技术，使我们能够观察到陶瓷材料，即：氧化铈-氧化锆陶瓷，在高温下的高分辨率条件下。我们的技术的建议发展作为这项研究的结果，将使我们能够观察纳米间隙设备的原子机制不久的将来。少

Two well known methods are often used to observe the electric/magnetic field distribution in a transmission electron microscope (TEM). The first one is electron holography, which requires a very expensive field-emission gun TEM (FEG TEM). The other one is Lorentz microscopy Though the latter method can be performed in a conventional TEM, the image in the Fresnel mode is obtained in defocused condition and, the image in the Foucault mode is not suitable for quantitative analysis.During in-situ electron holography experiments, we found a distortion of the image of the selected area diffraction (SAD) aperture in the very low magnification mode, celled "Low Mag" mode, while applying an external electrostatic potential to the specimen An analysis using geometrical optics for this phenomenon suggests that the distortion of the image can be correlated to the deflection of the electron beam by the electrostatic field at the level of a specimen. This method can be applied to the observation of … More the electric/magnetic field distribution by a conventional TEM without any additional apparatus.Geometrical electron optics of the shadow image distortion due to electric field in a conventional TEM has been analyzed, and the optical parameters to estimate the field strength have been determined in the system not only for the objective lens and the intermediate lens but also for the condenser lenses. The electrostatic potential distribution has been calculated along the electron beam passage and then compared to the observed value. The result shows that the integral of the horizontal part of electrostatic field can be measured quantitatively.The method we have developed has also been applied in some real materials.For example, a half cut Cu mesh with carton film fixed to the electrode at the specimen position has been observed. The 2D-maps showing the difference of the local field distribution has teen observed in the semicircle holes with and without the conductive carbon film which normalized the field in the hole. The whole shifts of the shadow image of the grid shaped aperture correspond to the field strength upper part of the specimen Separate detection of local field distribution at the specimen position and upper/lower part of the specimen is suggested. The electric field distribution around a FEG-emitter tip has also been observed by using our method.Through our research, several techniques to built the electrodes on to the side entry holder fir the TEM allowed us to observe the ceramics material, i.e., ceria-zirconia ceramics, in a high resolution condition at an elevated temperature. The suggested development of our technique as the results of this research will allow us to observe the atomistic mechanism of the nano-gap devices near future. Less