Ro-vibrational distribution measurement in transient discharges by coherent anti-Stokes Raman scattering (A02)

振动（和旋转）激发分子在等离子体化学中起着关键作用，因为它们具有高内能，强烈影响化学过程。一个悬而未决的问题是激发态在催化反应中的作用。分子的激发通过与等离子体中存在的高能电子的碰撞以及通过从已经激发的分子的激发转移而发生。详细的物理机制和速率常数往往是未知的或没有在实验中验证。此外，模拟通常非常复杂，特别是与大气压下的高度瞬态放电有关，其中时间尺度从电子相互作用的ps延伸到碰撞转移和化学反应的μs甚至ms。因此，本项目的目标是通过相干反斯托克斯拉曼散射（汽车）测量CO2和N2的振转激发。除了实验装置还开发了一种新的分析程序，可以解决非平衡分布函数。此外，分析模型允许从头预测的人口分布与电场数据和电流测量项目A1。证明了ns放电中等离子体密度和电场的独立控制。这允许将等离子体体中的电子的几乎全部能量优化耦合到振动激发中。

Vibrational (and rotational) excited molecules play a key role in plasma chemistry since due to their high internal energy they strongly affect the chemical processes. An open question is the role of excited states in catalytic reactions. The excitation of the molecules occurs by collisions with energetic electrons present in the plasma and by excitation transfer from already excited molecules. The detailed physical mechanisms and rate constants are often not known or have not been validated in experiments. Further, simulations are generally very involving, in particular in connection with highly transient discharges at atmospheric pressures, where time scales stretch from ps for the electron interaction to μs or even ms for collision transfer and chemical reactions. Therefore, this project aims at the measurement of the ro-vibrational excitation of CO2 and N2 by coherent anti-Stokes Raman scattering (CARS). In addition to the experimental setup also a new analysis procedure has been developed that allows addressing non-equilibrium distribution functions. Further, an analytical model allows ab-initio prediction of the population distributions with electric field data and current measurements taken from project A1. Independent control on plasma density and electric field in ns-discharges is demonstrated. This allows an optimized coupling of almost the entire energy of the electrons in the plasma bulk into vibrational excitation.