Experimental ground-state combination differences of CH5+
Experimental ground-state combination differences of CH5+
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DOI：
10.1126/science.aaa3304
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发表时间：
2015-03-20
期刊：
影响因子：
56.9
通讯作者：
Schlemmer, Stephan
中科院分区：
文献类型：
--
作者：
Asvany, Oskar;Yamada, Koichi M. T.;Schlemmer, Stephan
甲烷(CH4)的质子化反应是一种用量子力学很好地描述的相当刚性的分子，产生CH5+，这是一种典型的软质分子，一直未能得到明确的光谱描述。对纯CH5+样品的高分辨率光谱的实验测量是一个巨大的挑战。通过应用基于与CO2的光诱导反应和光抑制氦团簇生长的两种作用光谱，我们获得了低温、高分辨率的质量选择CH5+光谱。基于线位置的很高精度，我们确定了组合差值的频谱。对这一光谱的分析使得能够推导出CH5+相应的核自旋异构体的同样精确的基态方案，以及对这种可怕的分子光谱的试探性量子数指定。
Protonation of methane (CH4), a rather rigid molecule well described by quantum mechanics, produces CH5+, a prototypical floppy molecule that has eluded definitive spectroscopic description. Experimental measurement of high-resolution spectra of pure CH5+ samples poses a formidable challenge. By applying two types of action spectroscopy predicated on photoinduced reaction with CO2 and photoinhibition of helium cluster growth, we obtained low-temperature, high-resolution spectra of mass-selected CH5+. On the basis of the very high accuracy of the line positions, we determined a spectrum of combination differences. Analysis of this spectrum enabled derivation of equally accurate ground state-level schemes of the corresponding nuclear spin isomers of CH5+, as well as tentative quantum number assignment of this enfant terrible of molecular spectroscopy.