Mendis B G
Department of Physics, Durham University, South Road, Durham DH1 3LE, UK.
Ultramicroscopy. 2019 Nov;206:112816. doi: 10.1016/j.ultramic.2019.112816. Epub 2019 Jul 22.
Quantitative electron microscopy requires accurate simulation methods that take into account both elastic and inelastic scattering of the high energy electrons within the specimen. Here a method to combine plasmon excitations, the dominant energy loss mechanism in a solid, with conventional frozen phonon, multislice simulations is presented. The Monte Carlo based method estimates the plasmon scattering path length and scattering angle using random numbers and modifies the transmission and propagator functions in the multislice calculation accordingly. Comparison of energy filtered, convergent beam electron diffraction patterns in [110]-Si show good agreement between simulation and experiment. Simulations also show that plasmon excitation decreases the high angle annular dark field signal from atom columns, due to the plasmon scattering angle suppressing electron beam channeling along the atom columns. The effect on resolution and peak-to-background ratio of the atom columns is however small.
定量电子显微镜需要精确的模拟方法，该方法要考虑到高能电子在样品中的弹性散射和非弹性散射。本文提出了一种将等离子体激元激发（固体中主要的能量损失机制）与传统的冻结声子、多层模拟相结合的方法。基于蒙特卡罗的方法使用随机数估计等离子体激元散射路径长度和散射角，并相应地修改多层计算中的透射和传播函数。[110]-硅中能量过滤的会聚束电子衍射图案的比较表明模拟与实验结果吻合良好。模拟还表明，由于等离子体激元散射角抑制了沿原子列的电子束通道化，等离子体激元激发降低了原子列的高角度环形暗场信号。然而，对原子列的分辨率和峰背比的影响很小。
