Development and evaluation of a new transfer vessel for soft X-ray absorption spectroscopy

<p>Introduction</p><p>In recent years, analysis of light elements contained in materials such as batteries and catalysts has attracted attention. Soft X-ray absorption spectroscopy (XAS) is useful technique to analyze the light elements. In many cases of multi-element materials, however, it may not be possible to carry out XAS experiments for all the absorption edge in a beamline, since the coverage range of X-ray energy is limited in the beamline. It was difficult to keep samples across the beamline without atmospheric exposure. This is because the specifications of sample holders are different depending on the beamline. On the other hand, many materials such as batteries and catalysts are contaminated with oxygen, carbon dioxide and water when exposed to the atmosphere. Therefore, we developed a sample transfer vessel that can transport the sample from the glove box to the analyzer without exposing it to the atmosphere [1, 2]. Furthermore, in order to perform more precise analysis, we developed a sample transfer vessel with a small ion pump [3]. In this study, we have developed a transfer vessel that can measure the soft XAS across the beamline without exposing the sample to the atmosphere, based on the apparatus that we have developed.</p><p></p><p>Experimental</p><p>After heat treatment, the sample was attached to the transfer vessel in a glove box under an argon atmosphere and transported to the analyzer. Near edge X-ray absorption fine structure (NEXAFS) spectra of the sample using both total electron yield (TEY) and partial fluorescence yield (PFY) modes were measured at the beamline 2A of the UVSOR in the Institute of Molecular Science and at the beamline 12 of the SAGA-LS. For TEY, the drain current of the sample was measured. For PFY, fluorescence X-rays were collected using an energy dispersible silicon drift detector (SDD). All experiments were performed at room temperature.</p><p></p><p>Results and Discussion</p><p>Fig. 1 shows a photograph of the developed transfer vessel. This vessel consists of coaxial type linear motion feedthrough, vacuum vessel and sample holder. The sample is fixed to the holder using carbon tape. The sample current is measured using the Bayonet Neill-Concelman (BNC) connector on the upper part of the vessel. Since this vessel can be installed in a conflat flange with an outer diameter of 70 mm (ICF70), it can be connected if there is a free ICF70 port in the beamline or analyzer. We measured the Na K-edge NEXAFS spectra of NaCl powder obtained from TEY at SAGA-LS, and the Cl K-edge NEXAFS spectra at UVSOR. The Na K-edge NEXAFS spectrum is in good agreement with the theoretical calculation results reported by McIntrosh et al. [4], and the Cl K-edge NEXAFS spectrum is in good agreement with those of Orlando et al. [5]. From the above, we were able to measure two absorption edge energy spectra at the same point on the same sample without exposure to the atmosphere, using beamlines in different facilities. We also measured MgO using the same system, and obtained a spectrum without surface contamination. By using the new developed transfer vessel, the sample can be analyzed accurately with high precision.</p><p></p><p>References</p><p>[1] E. Kobayashi, J. Meikaku, T. Okajima, and H. Setoyama, Japanese Patent No. 5234994.</p><p>[2] E. Kobayashi, J. Meikaku, H. Setoyama, T. Okajima, J. Surf. Anal., 19, 2 (2012).</p><p>[3] E. Kobayashi, S. Tanaka, T. Okajima. J. Vac. Soc. Jpn. 59, 192 (2016).</p><p>[4] G. J. Mclntosh and A. Chan, Phys. Chem. Chem. Phys., 20, 24033 (2018).</p><p>[5] F. Orlando et al., Top. Catal., 59, 591 (2016).</p>