Research Center for Applied Science, Academia Sinica, Tapei 115, Taiwan.
Anal Chem. 2012 Nov 6;84(21):9318-23. doi: 10.1021/ac3020824. Epub 2012 Oct 12.
In the past decade, buckminsterfullerene (C(60))-based ion beams have been utilized in surface analysis instruments to expand their application to profiling organic materials. Although it had excellent performance for many organic and biological materials, its drawbacks, including carbon deposition, carbon penetration, continuous decay of the sputtering rate, and a rough sputtered surface, hindered its application. Cosputtering with C(60)(+) and auxiliary Ar(+) simultaneously and sample rotation during sputtering were proposed as methods to reduce the above-mentioned phenomena. However, the improvement from these methods has not been compared or studied under identical conditions; thus, the pros and cons of these methods are not yet known experimentally. In this work, a series of specimens including bulk materials and thin films were used to explore the differences between cosputtering and sample rotation on the analytical results. The results show that both of these methods can alleviate the problems associated with C(60)(+) sputtering, but each method showed better improvement in different situations. The cosputtering technique better suppressed carbon deposition, and could be used to generally improve results, especially with continuous spectra acquisition during sputtering (e.g., dynamic secondary ion mass spectrometry (SIMS) depth profiling). In contrast, for the scheme of sputter-then-acquire (e.g., alternative X-ray photoelectron spectrometry or dual-beam static SIMS depth profiling), a better result was achieved by sample rotation because it resulted in a flatter sputtered surface. Therefore, depending on the analytical scheme, a different method should be used to optimize the experimental conditions.
在过去的十年中，富勒烯（C(60)）基离子束已被用于表面分析仪器中，以扩展其在有机材料剖析方面的应用。尽管它对许多有机和生物材料具有优异的性能，但它的一些缺点，包括碳沉积、碳渗透、溅射率的连续衰减和粗糙的溅射表面，限制了其应用。同时进行 C(60)(+)和辅助 Ar(+)共溅射以及在溅射过程中旋转样品被提出作为减少上述现象的方法。然而，这些方法的改进并没有在相同的条件下进行比较或研究；因此，这些方法的优缺点在实验上还不清楚。在这项工作中，使用了一系列包括块状材料和薄膜的样品来探索共溅射和样品旋转对分析结果的差异。结果表明，这两种方法都可以缓解与 C(60)(+)溅射相关的问题，但每种方法在不同情况下都有更好的改进。共溅射技术可以更好地抑制碳沉积，并且可以普遍改善结果，特别是在溅射过程中进行连续光谱采集时（例如，动态二次离子质谱（SIMS）深度剖析）。相比之下，对于溅射-然后采集的方案（例如，交替 X 射线光电子能谱或双束静态 SIMS 深度剖析），通过样品旋转可以获得更好的结果，因为它会产生更平坦的溅射表面。因此，根据分析方案，应该使用不同的方法来优化实验条件。
