Abstract The study of Secondary Electron Yield (SEY) is widely performed to address important properties of materials to be used in a very wide spectrum of applications. It is, therefore, extremely important to understand the SEY dependence on material type, surface contaminants, structural quality and surface damage. We review here our recent studies of such items performed by looking at some representative conductive materials as noble metals and carbon based surfaces. Polycrystalline Ag, Au and Cu samples have been studied as introduced in the ultra-high vacuum chamber (therefore with an significant surface contamination) and after having been cleaned by ion sputtering. The comparison between the curves confirms that the SEY behavior is strongly influenced by the chemical state of the metal surfaces. We demonstrate the ability of SEY to determine work function values with high accuracy if the experimental system allows using very slow primary electrons. We also investigated, for the Cu sample, the effect on SEY of minimal amount of contaminants in the sub-monolayer regime showing that SEY is highly sensitive to the presence of adsorbates even at such very low coverages, specially for low energy primary electrons. In the case of C surfaces we summarize here the effect that the structural ordering of the C lattice has on the macroscopic SEY properties of ultrathin C layers. In particular we followed the SEY evolution during the thermal graphitization of thin amorphous carbon layers and during the amorphization of highly oriented pyrolytic graphite by means of Ar+ bombardment. In the first case the SEY decrease observed with the progressive conversion of sp3 hybrids into six-fold aromatic domains was related to the electronic structure of the C-films close to the Fermi level. We found that a moderate structural quality of the C layer, corresponding to aromatic clusters of limited size, is sufficient to obtain a SEY as low as ∼1. For the bombarded graphite, the strong lattice damage remains limited to the near surface layer, where the high density of defects reduces the transport of incoming and secondary electrons. Then, the SEY curves resulted differently modified in the low and high primary energy regions, but their maximal values remained favorably low. Our findings demonstrate that SEY, besides being an indispensable mean to qualify technical materials in many technological fields, can be also used as a flexible and advantageous diagnostics to probe surfaces and interfaces.

中文翻译：

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导电表面的 SEY 和低能 SEY

摘要 二次电子产率 (SEY) 的研究被广泛进行，以解决在非常广泛的应用中使用的材料的重要特性。因此，了解 SEY 对材料类型、表面污染物、结构质量和表面损伤的依赖性非常重要。我们在这里回顾了我们最近对此类项目的研究，通过查看一些具有代表性的导电材料（如贵金属和碳基表面）进行。研究了将多晶 Ag、Au 和 Cu 样品引入超高真空室（因此具有显着的表面污染）并通过离子溅射清洁后的样品。曲线之间的比较证实了 SEY 行为受金属表面化学状态的强烈影响。如果实验系统允许使用非常慢的初级电子，我们将展示 SEY 以高精度确定功函数值的能力。对于 Cu 样品，我们还研究了亚单层体系中最少量污染物对 SEY 的影响，表明即使在如此低的覆盖率下，SEY 对吸附物的存在也高度敏感，特别是对于低能初级电子。在 C 表面的情况下，我们在这里总结了 C 晶格的结构排序对超薄 C 层的宏观 SEY 特性的影响。特别是，我们在薄无定形碳层的热石墨化过程中和通过 Ar+轰击的高度取向热解石墨的非晶化过程中跟踪了 SEY 的演变。在第一种情况下，随着 sp3 杂化体逐渐转化为六重芳香域，观察到的 SEY 降低与接近费米能级的 C 膜的电子结构有关。我们发现 C 层的中等结构质量，对应于有限尺寸的芳香族簇，足以获得低至 1 的 SEY。对于轰击石墨，强烈的晶格损伤仍然仅限于近表面层，其中高密度的缺陷减少了传入和二次电子的传输。然后，SEY 曲线在低和高初级能量区域产生不同的修改，但它们的最大值仍然很低。我们的研究结果表明，SEY 不仅是在许多技术领域对技术材料进行鉴定的不可或缺的手段，