Using Fundamental Spectroscopy to Elucidate Kinetic and Energetic Mechanisms within Environmentally Relevant Inductively Coupled Plasma Systems

• Published in: The journal of physical chemistry. A, Molecules, spectroscopy, kinetics, environment, & general theory Molecules, spectroscopy, kinetics, environment, & general theory, 2017-10, Vol.121 (40), p.7627-7640
• Main Authors: Hanna, Angela R, Blechle, Joshua M, Fisher, Ellen R
• Format: Article
• Language: English
• ISSN: 1089-5639; 1520-5215
• DOI: 10.1021/acs.jpca.7b05311

Understanding energy distributions and kinetic processes in N x O y plasma systems is vital to realizing their potential in a range of applications, including pollution abatement. Energy partitioning between degrees of freedom and multiple molecules formed within N x O y plasma systems (N2, N2O, N2/O2) was investigated using both optical emission and broadband absorption spectroscopies. Specifically, we determined electron temperatures (T e) as well as rotational (T R) and vibrational (T V) temperatures for various N2 (B3Πg and C3Πu) and NO (X2Π and A2Σ+) states. T R and T V for both molecules (regardless of state) show a strong positive correlation with applied plasma power, as well as a negative correlation with system pressure. In all cases, T V values are significantly higher than T R for both species, suggesting vibrational modes are preferentially excited over rotational degrees of freedom. Time-resolved optical emission spectroscopy was utilized to determine rate constants, providing mechanistic insight and establishing the relationships between system parameters and plasma chemistry. Ultimately, the combination of these data allows us to glean information regarding both the kinetics and energetics of N2 and NO molecules formed within nitrogen- and oxygen-containing plasma systems for potential applications in gas remediation of pollutants.