Institute of Atomic and Molecular Sciences, Academia Sinica, P. O. Box 23-166, Taipei 10617, Taiwan.
J Chem Phys. 2018 Jan 7;148(1):014303. doi: 10.1063/1.5011797.
(2 + 1) resonance-enhanced multiphoton ionization (REMPI) detection of methyl radicals, in particular that via the intermediate 3p Rydberg states, has shown to be a powerful method and thus enjoyed a wide range of applications. Methyl has six vibrational modes. Among them-including partially and fully deuterated isotopologs-four out of twenty vibrational frequencies in the intermediate 3p states have so far eluded direct spectroscopic determination. Here, by exploiting the imaging spectroscopy approach to a few judiciously selected chemical reactions, the four long-sought REMPI bands-CHD(6), CHD(3), CHD(5), and CHD(6)-are discovered, which complete the REMPI identification for probing any vibrational mode of excitation of methyl radical and its isotopologs. These results, in conjunction with those previously reported yet scattered in the literature, are summarized here for ready reference, which should provide all necessary information for further spectral assignments and future studies of chemical dynamics using this versatile REMPI scheme.
（2+1）共振增强多光子电离（REMPI）检测甲基自由基，特别是通过中间 3p 里德伯态的检测，已被证明是一种强大的方法，因此得到了广泛的应用。甲基有六个振动模式。其中，包括部分和完全氘代同位素在内，在中间 3p 态的二十个振动频率中，有四个迄今仍无法通过直接光谱测定来确定。在这里，通过利用对几个经过精心选择的化学反应的成像光谱学方法，发现了四个长期以来被寻求的 REMPI 带-CHD(6)、CHD(3)、CHD(5)和 CHD(6)-，它们完成了探测甲基自由基及其同位素任何振动模式激发的 REMPI 鉴定。这些结果与之前在文献中零散报道的结果结合在一起，在这里进行了总结，以供参考，这应该为进一步的光谱分配以及使用这种多功能的 REMPI 方案进行未来的化学动力学研究提供所有必要的信息。
