Mendis Budhika G, Talmantaite Alina
Department of Physics, Durham University, South Road, Durham DH1 3LE, UK.
Microsc Microanal. 2022 Sep 5:1-10. doi: 10.1017/S1431927622012223.
The Compton signal in electron energy loss spectroscopy (EELS) is used to determine the projected electron momentum density of states for the solid. A frequent limitation however is the strong dynamical scattering of the incident electron beam within a crystalline specimen, i.e. Bragg diffracted beams can be additional sources of Compton scattering that distort the measured profile from its true shape. The Compton profile is simulated via a multislice method that models dynamical scattering both before and after the Compton energy loss event. Simulations indicate the importance of both the specimen illumination condition and EELS detection geometry. Based on this, a strategy to minimize diffraction artifacts is proposed and verified experimentally. Furthermore, an inversion algorithm to extract the projected momentum density of states from a Compton measurement performed under strong diffraction conditions is demonstrated. The findings enable a new route to more accurate electron Compton data from crystalline specimens.
电子能量损失谱（EELS）中的康普顿信号用于确定固体的投影电子动量态密度。然而，一个常见的限制是入射电子束在晶体样品内的强烈动态散射，即布拉格衍射束可能是康普顿散射的额外来源，会使测量轮廓偏离其真实形状。通过一种多层方法模拟康普顿轮廓，该方法对康普顿能量损失事件前后的动态散射进行建模。模拟结果表明了样品照明条件和EELS检测几何结构的重要性。基于此，提出了一种最小化衍射伪影的策略并通过实验进行了验证。此外，还展示了一种反演算法，用于从在强衍射条件下进行的康普顿测量中提取投影动量态密度。这些发现为从晶体样品获得更准确的电子康普顿数据开辟了一条新途径。
