Chang Yao, An Feng, Chen Zhichao, Luo Zijie, Zhao Yarui, Hu Xixi, Yang Jiayue, Zhang Weiqing, Wu Guorong, Xie Daiqian, Yuan Kaijun, Yang Xueming
State Key Laboratory of Molecular Reaction Dynamics and Dalian Coherent Light Source, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, 457 Zhongshan Road, Dalian, 116023, China.
Institute of Theoretical and Computational Chemistry, Key Laboratory of Mesoscopic Chemistry, School of Chemistry and Chemical Engineering Nanjing University, Nanjing, 210093, China.
Nat Commun. 2021 Nov 2;12(1):6303. doi: 10.1038/s41467-021-26599-9.
Vibrationally excited molecular hydrogen has been commonly observed in the dense photo-dominated regions (PDRs). It plays an important role in understanding the chemical evolution in the interstellar medium. Until recently, it was widely accepted that vibrational excitation of interstellar H was achieved by shock wave or far-ultraviolet fluorescence pumping. Here we show a further pathway to produce vibrationally excited H via the water photochemistry. The results indicate that the H fragments identified in the O(S) + H(XΣ) channel following vacuum ultraviolet (VUV) photodissociation of HO in the wavelength range of λ = 100-112 nm are vibrationally excited. In particular, more than 90% of H(X) fragments populate in a vibrational state v = 3 at λ112.81 nm. The abundance of water and VUV photons in the interstellar space suggests that the contributions of these vibrationally excited H from the water photochemistry could be significant and should be recognized in appropriate interstellar chemistry models.
在致密的光主导区域（PDRs）中普遍观测到了振动激发的分子氢。它在理解星际介质中的化学演化过程中起着重要作用。直到最近，人们普遍认为星际氢的振动激发是通过冲击波或远紫外荧光泵浦实现的。在此，我们展示了一种通过水的光化学产生振动激发氢的新途径。结果表明，在波长范围为λ = 100 - 112 nm的HO真空紫外（VUV）光解离后，在O(S) + H(XΣ)通道中识别出的H碎片是振动激发的。特别是，在λ112.81 nm时，超过90%的H(X)碎片处于振动量子数v = 3的状态。星际空间中水和VUV光子的丰度表明，水的光化学产生的这些振动激发氢的贡献可能很大，在适当的星际化学模型中应予以考虑。
