In situ analysis of plasma-induced material modifications on nanoparticles for functional applications

该项目的目标是获得等离子体诱导的小（<<100 nm）纳米颗粒（NPs）修饰的基本理解。它们的小尺寸可以导致量子限制效应（改变电学和光学性质），它们的高表面体积比使它们成为催化应用的理想的具有成本效益的候选者，并且它们的等离子体共振可以用于等离子体传感器。其中一个重要的参数是它们的表面状态（氧化、钝化等），这对它们的性能有很大的影响。非平衡等离子体是一种已知的NP生成和处理方法，具有几种独特的特性，如生成的NP尺寸分布狭窄、选择性加热或通过等离子体沉积、钝化或蚀刻进行有效的表面修饰。然而，在等离子体- np相互作用中起作用的过程只能定性地理解。利用紫外-可见吸收光谱原位分析NP表面等离子体共振，原位FTIR吸收光谱原位分析NP表面钝化和改性，实现项目目标。NPs将在单独的等离子体源中产生，安装在处理反应堆的百叶窗后面，这将使我们能够研究不同的等离子体条件和等离子体化学（氧化，氢钝化，甚至沉积）对新制备的具有明确尺寸和性能的NPs的影响。原位和额外的非原位表征技术将提供对等离子体- np相互作用的基本理解，并允许对其特性进行微调。一个重要的方面是，我们不会将等离子体用作“黑盒子”，而是系统地研究各种等离子体成分（离子、自由基等）如何影响小金属（Ag、Al、Ti）或半导体（Si） NPs的诱导变化。使用各种等离子体诊断技术（如Langmuir探针（LP），光学发射光谱（OES），质谱（MS）等）仔细分析等离子体特性是该项目的重要组成部分。计划中的研究将从两个pi的互补材料专业知识和等离子体专业知识的结合中受益匪浅。实现该项目的目标将使我们能够充分利用NP等离子体处理在生成高质量NP方面的潜力。例如，目标特性是优异的光学等离子体行为（用于宽带超材料吸收器或等离子体传感器的金属或TiN NPs）或硅NPs的优异光致发光率和短衰减时间（直接带隙行为），设想应用于硅基光源或第三代太阳能电池。

The goal of the project is to gain fundamental understanding of plasma-induced modifications of small (<<100 nm) nanoparticles (NPs). Their small size can lead to quantum confinement effects (changing electrical and optical properties), their high surface-to-volume ratio makes them ideal cost-effective candidates for catalytic applications, and their plasmon resonance can be utilized in plasmonic sensors. One of the important parameters is the state of their surface (oxidation, passivation, etc.), which influences very strongly their properties. Non-equilibrium plasmas are a known NP generation and treatment method with several unique properties such as narrow size distribution of generated NPs, selective heating, or effective surface modifications through plasma deposition, passivation, or etching. The processes playing a role in the plasma-NP interaction are, however, understood only qualitatively.The project goal will be pursued by applying in situ UV-Vis absorption spectroscopy to analyze the NP surface plasmon resonance and in situ FTIR absorption spectroscopy to analyze NP surface passivation and modification. The NPs will be generated in separate plasma sources mounted behind a shutter on a processing reactor, which will allow us to study the effects of different plasma conditions and plasma chemistries (oxidation, hydrogen passivation, or even deposition) on freshly-prepared NPs with well-defined size and properties. The in situ and additional ex situ characterization techniques will provide understanding of the fundamental plasma-NP interactions and allow fine-tuning of their properties.An important aspect is that we will not use the plasma as a "black box", but we will systematically study how various plasma components (ions, radicals, etc.) influence the induced changes on small metallic (Ag, Al, Ti) or semiconductor (Si) NPs. Careful analysis of plasma properties using a variety of plasma diagnostic techniques (e.g. Langmuir probe (LP), optical emission spectroscopy (OES), mass spectrometry (MS), etc.) is an essential part of this project. The planned research will strongly benefit from the combination of the complementary material expertise and plasma expertise of both PIs.Achieving the goal of this project will allow us to fully exploit the potential of NP plasma treatment in the generation of high-quality NPs. The targeted properties are, for example, excellent optical plasmonic behavior (metallic or TiN NPs for broadband metamaterial absorbers or plasmonic sensors) or excellent photoluminescence yield and short decay time (direct band gap behavior) of silicon NPs with envisaged application in silicon-based light sources or 3rd generation solar cells.