Konovalov Oleg V, Belova Valentina, La Porta Francesco, Saedi Mehdi, Groot Irene M N, Renaud Gilles, Snigireva Irina, Snigirev Anatoly, Voevodina Maria, Shen Chen, Sartori Andrea, Murphy Bridget M, Jankowski Maciej
ESRF - The European Synchrotron, 71 Avenue des Martyrs, 38043 Grenoble, France.
Leiden Institute of Chemistry, Leiden University, PO Box 9502, 2300 RA Leiden, The Netherlands.
J Synchrotron Radiat. 2022 May 1;29(Pt 3):711-720. doi: 10.1107/S1600577522002053. Epub 2022 Apr 1.
The X-ray reflectivity technique can provide out-of-plane electron-density profiles of surfaces, interfaces, and thin films, with atomic resolution accuracy. While current methodologies require high surface flatness, this becomes challenging for naturally curved surfaces, particularly for liquid metals, due to the very high surface tension. Here, the development of X-ray reflectivity measurements with beam sizes of a few tens of micrometres on highly curved liquid surfaces using a synchrotron diffractometer equipped with a double crystal beam deflector is presented. The proposed and developed method, which uses a standard reflectivity θ-2θ scan, is successfully applied to study in situ the bare surface of molten copper and molten copper covered by a graphene layer grown in situ by chemical vapor deposition. It was found that the roughness of the bare liquid surface of copper at 1400 K is 1.25 ± 0.10 Å, while the graphene layer is separated from the liquid surface by a distance of 1.55 ± 0.08 Å and has a roughness of 1.26 ± 0.09 Å.
X射线反射率技术能够以原子分辨率精度提供表面、界面和薄膜的面外电子密度分布。虽然目前的方法需要高表面平整度，但对于自然弯曲的表面，尤其是液态金属，由于其非常高的表面张力，这变得具有挑战性。在此，介绍了使用配备双晶束偏转器的同步加速器衍射仪在高度弯曲的液体表面上进行几十微米束斑尺寸的X射线反射率测量的进展。所提出和开发的方法使用标准反射率θ-2θ扫描，成功地用于原位研究熔融铜的裸露表面以及通过化学气相沉积原位生长的石墨烯层覆盖的熔融铜表面。结果发现，1400 K时铜的裸露液体表面粗糙度为1.25±0.10 Å，而石墨烯层与液体表面的间距为1.55±0.08 Å，粗糙度为1.26±0.09 Å。
