Applied X-ray spectroscopy

How to clean metals

In early February a team led by Curran, including Prajna, Yujiang and Anna, visited beamline I09 at Diamond Light Source in an attempt to collect soft and hard X-ray photoelectron spectroscopy (SXPS and HAXPES) data on the pure metals titanium and yttrium. Sounds simple, but obtaining clean metal surfaces, and more importantly maintaining clean surfaces during measurement, is a real challenge for these two. Titanium in particular finds application as a so-called getter material, where its high reactivity is used to absorb stray molecules in vacuum chambers to achieve ultra-high vacuum (UHV) conditions. Great for vacuum chambers, not ideal when you need to keep a titanium surface free of adsorbates. After some not entirely successful previous attempts, a combination of ex-situ chemical etching, in-situ argon etching, and keeping the samples at a few hundred toasty degrees during measurement proofed to be the magical combination to obtain perfect metallic spectra. Such high quality reference datasets are crucial to aid the exploration and understanding of complex systems, where convoluted spectral data can prove to be a formidable challenge. This data will support Curran’s ongoing work on metallisation schemes for power electronics (read more about some of the work here and here) and further projects on energy materials and catalysts. As always the beamtime was masterfully supported by Pardeep Kumar. This was also the first synchrotron experience for Prajna and Yujiang.

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