Department of Mining and Materials Engineering, McGill University, 3610 University, Montreal, Qc., Canada H3A 0C5.
Department of Optics, Faculty of Physical Sciences, Universidad Complutense de Madrid, Pza. Ciencias 1, Ciudad Universitaria 28040, Madrid, Spain.
Micron. 2019 Nov;126:102737. doi: 10.1016/j.micron.2019.102737. Epub 2019 Aug 23.
The effects of thermal diffuse scattering on diffraction of highly-accelerated electrons by crystal lattices are investigated with a method that combines the frozen phonon approximation with an exact numerical solution of the time-dependent Schrödinger equation. The phonon configuration for each single-electron diffraction process is determined by means of Einstein's model. It is shown that this procedure provides the possibility of describing and explaining, in a natural way, after averaging over a number of electron realizations, how the typical diffraction features that characterize a fully coherent pattern are gradually suppressed by thermally-induced incoherence. This is achieved by a controlled increase of the lattice atomic vibrations and is in contrast to the use of attenuating Debye-Waller factors and complex potential absorbers. A lattice with reduced dimensionality is first considered as a working model, where the method renders results compatible with those reported in the literature. Subsequently, a full three-dimensional system is simulated and results are compared to experimental imaging displaying the method's reliability.
采用将冻结声子近似与含时薛定谔方程的精确数值解相结合的方法，研究了热漫散射对晶格中高加速电子衍射的影响。通过爱因斯坦模型确定了每个单电子衍射过程的声子构型。结果表明，该方法通过对大量电子实现的平均化，自然地提供了描述和解释的可能性，即在热诱导非相干作用下，完全相干模式的典型衍射特征是如何逐渐被抑制的。这是通过晶格原子振动的受控增加来实现的，与使用衰减的德拜-沃勒因子和复势吸收器形成对比。首先，将低维晶格作为工作模型进行考虑，其中该方法使结果与文献中报道的结果相兼容。随后，对全三维系统进行了模拟，并将结果与显示该方法可靠性的实验成像进行了比较。
