Bent crystal Laue analyser combined with total reflection fluorescence X‐ray absorption fine structure (BCLA + TRF‐XAFS) and its application to surface studies

• Published in: Journal of synchrotron radiation Vol. 27; no. 6; pp. 1618 - 1625
• Main Authors: Wakisaka, Yuki, Hu, Bing, Kido, Daiki, Al Rashid, Md. Harun, Chen, Wenhan, Dong, Kaiyue, Wada, Takahiro, Bharate, Bapurao, Yuan, Quiyi, Mukai, Shingo, Takeichi, Yasuo, Takakusagi, Satoru, Asakura, Kiyotaka
• Format: Journal Article
• Language: English
• Published: 5 Abbey Square, Chester, Cheshire CH1 2HU, England International Union of Crystallography 01-11-2020; John Wiley & Sons, Inc
• Subjects: Absorption; bent crystal Laue analyser; Elastic scattering; Fine structure; Fluorescence; Footprints; Gold; in situ surface X‐ray absorption fine structure; Metal foils; Platinum; Reflection; Spectrum analysis; Substrates; Surface analysis (chemical); Surface chemistry; total reflection fluorescence X‐ray absorption fine structure; X‐ray absorption fine structure
• ISSN: 1600-5775; 0909-0495; 1600-5775
• DOI: 10.1107/S1600577520011170

A bent crystal Laue analyser (BCLA) is an X‐ray energy analyser used for fluorescence X‐ray absorption fine‐structure (XAFS) spectroscopy to separate the fluorescence X‐ray emission line of a target atom from the elastic scattering X‐rays and other fluorescence emission lines. Here, the feasibility of the BCLA for total reflection fluorescence XAFS (TRF‐XAFS), which has a long X‐ray footprint on the substrate surface owing to grazing incidence, was tested. The focal line of the BCLA was adjusted on the X‐ray footprint and the XAFS signal for one monolayer of Pt deposited on a 60 nm Au film with high sensitivity was obtained. Although range‐extended XAFS was expected by the rejection of Au fluorescence arising from the Au substrate, a small glitch was found in the Au L3 edge because of the sudden change of the complex refraction index of the Au substrate at the Au edge. This abnormal spectrum feature can be removed by reflectivity correction using Au foil absorption data. BCLA combined with TRF‐XAFS spectroscopy (BCLA + TRF‐XAFS) is a new technique for the in situ surface analysis of highly dispersed systems even in the presence of a liquid overlayer.
A bent crystal Laue analyser combined with total reflection fluorescence X‐ray absorption fine structure is a promising technique for in situ surface analysis of highly dispersed systems even in the presence of solution.