Atmospheric pressure plasma jets have great potential for the surface modification of polymers. In this work, the authors report on polystyrene etching by a radio frequency driven atmospheric pressure plasma jet with a focus on the role of ${\mathrm{H}}^{\cdot }$, ${\mathrm{O}}^{\cdot }$, and ${}^{\cdot }\mathrm{OH}$ radicals in this process. The absolute flux of ${\mathrm{H}}^{\cdot }$, ${\mathrm{O}}^{\cdot }$, and ${}^{\cdot }\mathrm{OH}$ radicals reaching the surface of the polymer was determined by a comsol multiphysics reacting fluid dynamics model incorporating detailed transport phenomena in the boundary layer near the substrate. The simulated results of ${\mathrm{H}}^{\cdot }$ and ${}^{\cdot }\mathrm{OH}$ densities in the jet effluent were experimentally verified by two-photon absorption laser induced fluorescence and laser induced fluorescence, respectively. The carbon atom removal flux from the polystyrene surface was taken from previously reported measurements using the same plasma source. The authors show that the boundary layer effects in the interfacial region above the substrate can have a significant impact on the calculated etching probabilities. The reaction probability ($\beta$) has a significant uncertainty although a variation of 2 orders of magnitude in $\beta$ leads to uncertainties of approximately 1 order of magnitude variation in the determined etching probability. The etching probability of polystyrene by ${}^{\cdot }\mathrm{OH}$ radicals was confirmed to be at least an order of magnitude larger than the polystyrene etching probability by ${\mathrm{O}}^{\cdot }$ radicals. The authors also confirmed the weak polystyrene etching probability by ${\mathrm{H}}^{\cdot }$ radicals. The model suggests that the presence of a 30 ppm ${\mathrm{O}}_2$ impurity can lead to the production of ${}^{\cdot }\mathrm{OH}$ radicals in the far effluent of the $\mathrm{Ar}+1\text{\%}{\mathrm{H}}_2$ plasma jet close to the substrate at sufficient densities to enable effective etching.

中文翻译：

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射频驱动大气压等离子体射流获得的聚苯乙烯的O·，H·和·OH自由基刻蚀几率

大气压等离子体射流具有聚合物表面改性的巨大潜力。在这项工作中，作者报告了通过射频驱动的大气压等离子射流进行聚苯乙烯蚀刻的方法，重点是聚苯乙烯的作用。${\mathrm{H}}^{\cdot }$， ${\mathrm{Ø}}^{\cdot }$和 ${}^{\cdot }\mathrm{哦}$自由基在这个过程中。的绝对通量${\mathrm{H}}^{\cdot }$， ${\mathrm{Ø}}^{\cdot }$和 ${}^{\cdot }\mathrm{哦}$通过Comsol多物理场反应流体动力学模型确定到达聚合物表面的自由基，该模型在靠近基材的边界层中结合了详细的传输现象。仿真结果${\mathrm{H}}^{\cdot }$ 和 ${}^{\cdot }\mathrm{哦}$通过两个光子吸收激光诱导的荧光和激光诱导的荧光分别通过实验验证了射流中的密度。来自聚苯乙烯表面的碳原子去除通量是使用相同的等离子体源从先前报道的测量中获得的。作者表明，衬底上方界面区域中的边界层效应可能对计算出的蚀刻概率产生重大影响。反应概率（$\beta$）具有很大的不确定性，尽管 $\beta$在确定的蚀刻概率中导致大约1个数量级变化的不确定性。聚苯乙烯的腐蚀概率${}^{\cdot }\mathrm{哦}$ 自由基被证实比聚苯乙烯蚀刻概率至少大一个数量级 ${\mathrm{Ø}}^{\cdot }$部首。作者还证实了通过${\mathrm{H}}^{\cdot }$部首。该模型表明存在30 ppm${\mathrm{Ø}}_2$ 杂质会导致 ${}^{\cdot }\mathrm{哦}$ 自由基中的自由基 $\mathrm{氩气}+\mathrm{1个}\text{％}{\mathrm{H}}_2$ 等离子流以足够的密度靠近基板，以实现有效蚀刻。