Determination of molecular temperatures within low-temperature plasmas is critical to understanding the reactions that drive the chemistry of these systems and the mechanisms involved in plasma-surface interactions. Optical emission spectroscopy was employed to investigate gas-phase processes in H₂ and CH₄ inductively coupled plasma systems. Specifically, rotational temperatures (T_R) have been determined for H₂ $d^3{\mathrm{\Pi }}_u\to a^3{\mathrm{\Sigma }}_g^{+}$ and CH ${\mathrm{A}}^2\mathrm{\Delta }\to {\mathrm{X}}^2\mathrm{\Pi }$ under a variety of plasma parameter conditions. In 100% H₂ plasmas, T_R(H₂) values are ∼500–550 K, whereas generally higher T_R(H₂) values (∼500–700 K) are reported for 100% CH₄ plasmas. Disparities in the rotational temperature values and trends of H₂ $(d^3{\mathrm{\Pi }}_u)$ between H₂ and CH₄ plasmas highlight the differences in H₂ excitation pathways occurring in each of these two plasma systems as T_R can be affected by the mechanism for molecule formation and excitation within plasma systems. As such, mixed gas CH₄/H₂ plasma systems were also explored to gain further insight into these mechanistic details. These results emphasize the connections between fundamental plasma properties and plasma parameters, a key component to understanding and optimizing plasma conditions for the future development of a host of plasma technologies.

中文翻译：

---

H2和CH4电感耦合等离子体的气相诊断研究

确定低温等离子体内的分子温度对于理解驱动这些系统化学反应的反应以及等离子体与表面相互作用所涉及的机理至关重要。使用光发射光谱法研究H ₂和CH ₄电感耦合等离子体系统中的气相过程。具体而言，已确定了H _2的旋转温度（T _R） $d^3{\mathrm{\Pi }}_{ü}\to {\mathrm{一种}}^3{\mathrm{\Sigma }}_G^{+}$ 和CH ${\mathrm{一种}}^2\mathrm{\Delta }\to {\mathrm{X}}^2\mathrm{\Pi }$在各种血浆参数条件下。在100％的H _2个等离子体，Ť _{- [R}（H ₂）的值是~500-550 K，而一般较高Ť _{- [R}（H ₂）的值（~500-700 K）报道了100％的CH _4个等离子体。旋转温度值的差异和H _2的趋势 $（d^3{\mathrm{\Pi }}_{ü}）$H ₂和CH ₄等离子体之间的“ H _2”突出显示了在这两个等离子体系统的每一个中发生的H ₂激发途径的差异，因为T _R会受到等离子体系统内分子形成和激发机制的影响。因此，还研究了混合气体CH ₄ / H ₂等离子体系统，以进一步了解这些机械细节。这些结果强调了基本等离子特性与等离子参数之间的联系，这是了解和优化等离子条件的关键组成部分，以用于众多等离子技术的未来发展。