Nagasaka Masanari
Institute for Molecular Science, Myodaiji, Okazaki 444-8585, Japan.
J Synchrotron Radiat. 2020 Jul 1;27(Pt 4):959-962. doi: 10.1107/S1600577520005883. Epub 2020 May 27.
The soft X-ray region below 200 eV is important for investigating chemical and biological phenomena since it covers K-edges of Li and B and L-edges of Si, P, S and Cl. Helium gas is generally used as the soft X-ray transmission window for soft X-ray absorption spectroscopy (XAS) under atmospheric conditions. However, the helium gas window cannot be applied to XAS in the low-energy region since transmitted soft X-rays mostly consist of high-order X-rays due to the low transmission of first-order X-rays. In this study, the argon gas window is proposed as a new soft X-ray transmission window in the low-energy region. High-order X-rays are removed by the absorption of the Ar L-edge (240 eV), and first-order X-rays become the major contribution of transmitted soft X-rays in the low-energy region. Under atmospheric argon conditions, the double-excitation Rydberg series of helium gas (60 eV), Si L-edge XAS of an SiN membrane (100 eV) and S L-edge XAS of dimethyl sulfoxide gas (170 eV) are successfully measured, indicating that the argon gas window is effective for soft X-ray transmission in the low-energy region from 60 eV to 240 eV.
200电子伏特以下的软X射线区域对于研究化学和生物现象很重要，因为它涵盖了锂和硼的K边以及硅、磷、硫和氯的L边。在大气条件下，氦气通常用作软X射线吸收光谱（XAS）的软X射线透射窗口。然而，由于一阶X射线的低透射率，透射的软X射线大多由高阶X射线组成，因此氦气窗口不能应用于低能区域的XAS。在本研究中，提出了氩气窗口作为低能区域新的软X射线透射窗口。通过氩L边（240电子伏特）的吸收去除高阶X射线，一阶X射线成为低能区域透射软X射线的主要贡献。在大气氩条件下，成功测量了氦气的双激发里德堡系列（60电子伏特）、SiN膜的Si L边XAS（100电子伏特）和二甲基亚砜气体的S L边XAS（170电子伏特），表明氩气窗口对于60电子伏特至240电子伏特的低能区域的软X射线透射是有效的。
