Politano Antonio
Department of Physical and Chemical Sciences, University of L'Aquila, via Vetoio, 67100 L'Aquila, Abruzzo, Italy.
CNR-IMM Istituto per la Microelettronica e Microsistemi, VIII strada 5, I-95121 Catania, Italy.
Phys Chem Chem Phys. 2021 Dec 1;23(46):26061-26069. doi: 10.1039/d1cp03804d.
From its advent, high-resolution electron energy loss spectroscopy (HREELS) has emerged as one of the most versatile tools in surface science. In the last few decades, HREELS was widely used for the fundamental study of (i) chemical reactions at the surfaces of model catalysts (mostly single crystals), (ii) lattice dynamics (phonons), (iii) surface plasmons and (iv) magnons. However, HREELS has experienced a continuous decay of the number of daily users worldwide so far, due to several factors. However, the rise of Dirac materials (graphene, topological insulators, Dirac semimetals) offers new perspectives for HREELS, due to its unique features enabling ultrasensitive detection of (i) chemical modifications at their surfaces, (ii) Kohn anomalies arising from electron-phonon coupling and (iii) novel plasmonic excitations associated to Dirac-cone fermions, as well as their eventual mutual interplay with other plasmon resonances related to topologically trivial electronic states. By selected case-study examples, here we show that HREELS can uniquely probe these phenomena in Dirac materials, thus validating its outstanding relevance and its irreplaceability in contemporary solid-state physics, thus paving the way for a renewed interest. In addition, recent technological upgrades enable the combination of HREELS as an add-on to photoemission apparatuses for parallel readout of energy and momentum of surface excitations. Open issues for theoretical modelling of HREELS related to the dependence on primary electron beam energy and scattering geometry are also critically presented.
自问世以来，高分辨电子能量损失谱（HREELS）已成为表面科学中用途最广泛的工具之一。在过去几十年里，HREELS被广泛用于以下基础研究：（i）模型催化剂（主要是单晶）表面的化学反应；（ii）晶格动力学（声子）；（iii）表面等离子体激元；（iv）磁振子。然而，由于多种因素，迄今为止，HREELS在全球范围内的日用户数量持续减少。不过，狄拉克材料（石墨烯、拓扑绝缘体、狄拉克半金属）的兴起为HREELS提供了新的视角，因为其独特特性能够实现对以下方面的超灵敏检测：（i）其表面的化学修饰；（ii）由电子 - 声子耦合产生的科恩反常；（iii）与狄拉克锥费米子相关的新型等离子体激元激发，以及它们最终与其他与拓扑平凡电子态相关的等离子体共振之间的相互作用。通过选取案例研究示例，我们在此表明，HREELS能够独特地探测狄拉克材料中的这些现象，从而验证了其在当代固态物理学中的突出相关性和不可替代性，为重新引发人们的兴趣铺平了道路。此外，最近的技术升级使得HREELS能够作为光发射设备的附加装置，用于并行读取表面激发的能量和动量。本文还批判性地提出了与初级电子束能量和散射几何结构依赖性相关的HREELS理论建模的开放性问题。
