Warneke Ziyan, Rohdenburg Markus, Warneke Jonas, Kopyra Janina, Swiderek Petra
University of Bremen, Faculty 2 (Chemistry/Biology), Institute of Applied and Physical Chemistry, Leobener Straße / NW 2, Postfach 330440, D-28334 Bremen, Germany.
Pacific Northwest National Laboratory, Physical Science Division, Richland, WA, USA.
Beilstein J Nanotechnol. 2018 Jan 8;9:77-90. doi: 10.3762/bjnano.9.10. eCollection 2018.
Focused electron beam induced deposition (FEBID) is a versatile tool for the direct-write fabrication of nanostructures on surfaces. However, FEBID nanostructures are usually highly contaminated by carbon originating from the precursor used in the process. Recently, it was shown that platinum nanostructures produced by FEBID can be efficiently purified by electron irradiation in the presence of water. If such processes can be transferred to FEBID deposits produced from other carbon-containing precursors, a new general approach to the generation of pure metallic nanostructures could be implemented. Therefore this study aims to understand the chemical reactions that are fundamental to the water-assisted purification of platinum FEBID deposits generated from trimethyl(methylcyclopentadienyl)platinum(IV) (MeCpPtMe). The experiments performed under ultrahigh vacuum conditions apply a combination of different desorption experiments coupled with mass spectrometry to analyse reaction products. Electron-stimulated desorption monitors species that leave the surface during electron exposure while post-irradiation thermal desorption spectrometry reveals products that evolve during subsequent thermal treatment. In addition, desorption of volatile products was also observed when a deposit produced by electron exposure was subsequently brought into contact with water. The results distinguish between contributions of thermal chemistry, direct chemistry between water and the deposit, and electron-induced reactions that all contribute to the purification process. We discuss reaction kinetics for the main volatile products CO and CH to obtain mechanistic information. The results provide novel insights into the chemistry that occurs during purification of FEBID nanostructures with implications also for the stability of the carbonaceous matrix of nanogranular FEBID materials under humid conditions.
聚焦电子束诱导沉积（FEBID）是一种用于在表面直接书写制造纳米结构的通用工具。然而，FEBID纳米结构通常会被该过程中使用的前驱体产生的碳高度污染。最近的研究表明，在水存在的情况下，通过电子辐照可以有效地纯化FEBID制备的铂纳米结构。如果这种方法能够应用于由其他含碳前驱体制备的FEBID沉积物，那么就可以实现一种生成纯金属纳米结构的新通用方法。因此，本研究旨在了解对于由三甲基（甲基环戊二烯基）铂（IV）（MeCpPtMe）制备的铂FEBID沉积物进行水辅助纯化至关重要的化学反应。在超高真空条件下进行的实验采用了不同的解吸实验与质谱联用的方法来分析反应产物。电子激发解吸监测电子辐照期间离开表面的物质，而辐照后热解吸光谱则揭示后续热处理过程中释放的产物。此外，当电子辐照产生的沉积物随后与水接触时，还观察到了挥发性产物的解吸。结果区分了热化学、水与沉积物之间的直接化学反应以及电子诱导反应对纯化过程的贡献。我们讨论了主要挥发性产物CO和CH的反应动力学，以获取机理信息。这些结果为FEBID纳米结构纯化过程中发生的化学过程提供了新的见解，这对纳米颗粒FEBID材料的碳质基质在潮湿条件下的稳定性也具有重要意义。
