Photon-energy dependence of single-photon simultaneous core ionization and core excitation in CO2
Photon-energy dependence of single-photon simultaneous core ionization and core excitation in CO2
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DOI：
10.1103/physreva.94.013416
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发表时间：
2016-07-20
影响因子：
2.9
通讯作者：
Penent, F.
中科院分区：
文献类型：
--
作者：
Carniato, S.;Selles, P.;Penent, F.
本文研究了CO_2分子中K壳层同时电离和激发的K-2 V过程。我们将这些K-2 V态定义为超级震荡，与“常规”K（-1）v（-1）V震荡态不同。虽然传统震荡卫星的性质和光子能量的演变一直是许多研究的对象，但以前没有关于超级震荡的大光子能量范围的数据。CO2分子是一个教科书上的例子，因为它表现出两个很好的分离的K-2 V共振（V为2 π（u）* 和5 δ g*），具有不同的对称性，这是由不同起源的震动过程以可比的比例填充而产生的。这两个共振的激发截面的变化与光子能量的报告，使用两种不同的实验方法，揭示了激发机制。此外，双芯孔光谱被证明是能够整合，甚至扩展由传统的单芯孔X射线光电子能谱（XPS）和近边缘X射线吸收精细结构（NEXAFS）技术提供的信息，揭示，例如，g-g偶极禁戒跃迁，仅在NEXAFS光谱通过振动耦合激发。
We have studied the K-2V process corresponding to simultaneous K-shell ionization and K-shell excitation in the CO2 molecule. We define these K-2V states as super shake-up, at variance with the "conventional" K(-1)v(-1)V shake-up states. While the nature and evolution with photon energy of the conventional shake-up satellites has been the object of many studies, no such data on a large photon-energy range were previously reported on super shake-up. The CO2 molecule is a textbook example because it exhibits two well-isolated K-2V resonances (with V being 2 pi(u)* and 5 delta g*) with different symmetries resulting from shake-up processes of different origin populated in comparable proportions. The variation of the excitation cross section of these two resonances with photon energy is reported, using two different experimental approaches, which sheds light on the excitation mechanisms. Furthermore, double-core-hole spectroscopy is shown to be able to integrate and even expand information provided by conventional single-core-hole X-ray Photoelectron Spectroscopy (XPS) and Near-Edge X-ray Absorption Fine Structure (NEXAFS) techniques, revealing, for instance, g-g dipole forbidden transitions which are only excited in NEXAFS spectra through vibronic coupling.