CAREER: Controlling Low Temperature Plasma Activation

低温等离子体(LTPS)已被成功地用来激发相对惰性物质进入促进有用化学反应的状态。LTPS的应用很广泛，包括粘接先进的轻质结构材料、半导体加工、二氧化碳利用、废水处理、等离子体辅助伤口愈合和农业技术。LTP激活过程的发现和探索历来是通过反复试验进行的，这是昂贵和耗时的。该方案旨在加深对LTPS的基本认识，以加速基于LTPS的新应用的开发。本项目的研究假设是LTPS中发生的化学反应向超局域平衡态发展，该平衡态可以从第一性原理推导出来。初步数据支持这一假设，该假设将通过对能源和环境应用感兴趣的气相反应进行进一步的实验验证。在超局部平衡条件下，不同物种在空间的同一位置可以有不同的温度。LTPS中超局域平衡态是背景气体温度、电子温度、总压、电子浓度和不同物种摩尔数的函数。包含碳、氢和氧的化学体系将被研究，这些体系在能源和环境应用方面具有相当大的兴趣，二氧化碳和甲烷是两个关键分子。为了表征C-H-O体系的多相特性，将开发一种稳健可靠的方法来测量产生固体的LTPS中宽压力范围内的等离子体参数。研究和教育的整合将专注于与当地一所高中的化学教师合作，为高中生和在华盛顿大学学习热力学课程的本科生开发关于化学平衡的积极学习模块。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

Low temperature plasmas (LTPs) have been used successfully to excite relatively inert materials into states that promote useful chemical reactions. Applications of LTPs are diverse and include bonding of advanced lightweight structural materials, semiconductor processing, carbon dioxide utilization, wastewater treatment, plasma-assisted wound healing, and agricultural technologies. The discovery and exploration of LTP activation processes has historically proceeded by trial and error, which is expensive and time-consuming. This proposal aims to develop a fundamental understanding of LTPs to accelerate the development of new applications based on them.The research hypothesis of this project is that chemical reactions occurring in LTPs proceed towards a superlocal equilibrium state, which can be derived from first principles. Preliminary data supports the hypothesis, which will be further tested experimentally using gas-phase reactions that are of interest for energy and environmental applications. Under conditions of superlocal equilibrium, different species can have different temperatures at the same location in space. The superlocal equilibrium state in LTPs is expected to be a function of the background gas temperature, electron temperature, total pressure, electron concentration, and mole numbers of different species. Chemical systems containing carbon, hydrogen and oxygen will be studied that are of considerable interest for energy and environmental applications, with carbon dioxide and methane being two key molecules. To characterize the C-H-O system, which is multiphase, a robust and reliable method will be developed to measure plasma parameters over a wide pressure range in LTPs that produce solids. Integration of research and education will be focused on developing active learning modules on chemical equilibria for high school students, in collaboration with a Chemistry Teacher from a local High School, and for undergraduate students taking a Thermodynamics course at Washington University.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.