论文标题
低压EUV光化学实验：对泰坦大气中发生的离子化学的见解
Low Pressure EUV Photochemical Experiments: Insight on the Ion-Chemistry Occurring in Titan's Atmosphere
论文作者
论文摘要
得益于\ textit {cassini}船上仪器上的航天器，众所周知，泰坦的电离层化学是复杂的，并且通过直接在上层大气中的最丰富物种的光解而引发了分子生长。在光解形成的化合物池中，N含N含物种参与了雾化的形成，但是化学融合途径需要更好地受到约束。} \\在这项工作中，我们进行了低压的EUV光化学实验室实验。 APSIS反应堆充满了n $ _2 $/ch $ _4 $（90/10 \％）的气体混合物与泰坦高层大气有关的气体混合物。通过使用73.6 nm {的EUV光子源（在实验室中很难进行以前的研究）生产的EUV光子源来照射细胞。用四极质量光谱仪监测光产物（中性物种和离子物种）\ textit {原位}。化学途径是通过面对光产物的实验观测和数值预测来解释的。 \\这项工作中最有趣的结果是，甲氨酸是实验过程中唯一检测到的稳定的N含N的中性分子，它依赖于N $ _2^+$的产生。该实验结果与泰坦大气的一维化学模型所预测的相对较高的丰度一致，并舒适地甲基亚胺作为形成含有复杂N含N的有机分子的中间。最大程度地减少来自壁表面反应的偏差。}
Thanks to the \textit{Cassini} spacecraft onboard instruments, it has been known that Titan's ionospheric chemistry is complex and the molecular growth is initiated through the photolysis of the most abundant species directly in the upper atmosphere. Among the pool of chemical compounds formed by the photolysis, N-bearing species are involved in the haze formation but the chemical incorporation pathways need to be better constrained.}\\ In this work, we performed low-pressure EUV photochemical laboratory experiments. The APSIS reactor was filled with a N$_2$/CH$_4$ (90/10\%) gas mixture relevant to the upper atmosphere of Titan. The cell was irradiated by using a EUV photon source at 73.6 nm {which has been difficult to produce in the laboratory for previous studies.}. The photoproducts (both neutral and ionic species) were monitored \textit{in situ} with a quadrupole mass spectrometer. The chemical pathways are explained by confronting experimental observations and numerical predictions of the photoproducts. \\ The most interesting result in this work is that methanimine was the only stable N-bearing neutral molecule detected during the experiments and it relies on N$_2^+$ production. This experimental result is in agreement with the relatively high abundance predicted by 1D-photochemical models of Titan's atmosphere and comforts methanimine as an intermediate towards the formation of complex N-bearing organic molecules.\\ {This experiment is only testing one part of the overall chemical scheme for Titan's upper atmosphere due to the selective wavelength but demonstrates the capability to probe the chemical pathways occurring in Titan's atmosphere by minimizing bias coming from wall surface reactions.}
