The development of optical systems operating in the far ultraviolet range (FUV, λ=100-200 nm) is limited by the efficiency of passivated aluminum (Al) mirrors. Although it is presently possible to obtain high-reflectivity FUV mirrors through physical vapor deposition, the process involves deposition with substrates at high temperatures, which is technically challenging for large optical elements. A novel passivation procedure for bare Al mirrors is reported. The treatment consisted of using a low-temperature electron-beam generated plasma produced in a gas mixture of Ar and SF₆ to etch away the native oxide layer from the Al film, while simultaneously promoting the generation of a thin aluminum tri-fluoride (AlF₃) layer on the Al surface. In the first section we analyze the effect of varying both ion energy and SF₆ concentration on the FUV reflectance, thickness, composition, and surface morphology of the resulting AlF₃ protective layers. In the second section, the reflectivity of samples is optimized at selected important FUV wavelengths for astronomical observations. Notably, samples attained state-of-the-art reflectances of 75% at 108.5 nm (He Lyman γ), 91% at 121.6 nm (H Lyman α), 90% at 130.4 nm (OI), and of 95% at 155.0 nm (C IV). The stability over time of these passivated mirrors is also investigated.

中文翻译：

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使用电子束产生的等离子体在室温下进行等离子刻蚀和远紫外Al镜的表面钝化

在远紫外线范围（FUV，λ= 100-200 nm）中操作的光学系统的发展受到钝化铝（Al）反射镜效率的限制。尽管目前有可能通过物理气相沉积获得高反射率的FUV镜，但该过程涉及在高温下用基板进行沉积，这对大型光学元件而言在技术上具有挑战性。据报道，一种新颖的钝化铝镜钝化工艺。该处理包括使用在Ar和SF ₆的气体混合物中产生的低温电子束产生的等离子体，从Al膜上蚀刻掉天然氧化物层，同时促进薄三氟化铝（AlF）的产生。₃）层在铝表面上。在第一部分中，我们分析了改变离子能量和SF ₆浓度对所得的AlF ₃保护层的FUV反射率，厚度，组成和表面形态的影响。在第二部分中，针对天文观测，在选定的重要FUV波长下优化了样品的反射率。值得注意的是，样品在108.5 nm（He Lymanγ）处达到75％的反射率，在121.6 nm（H Lymanα）处达到91％的反射率，在130.4 nm（OI）处达到90％的反射率，在155.0处达到95％的反射率nm（C IV）。还研究了这些钝化镜随时间的稳定性。