Soft X-Ray Induced Radiation Damage in Dip-and-Pull Photon Absorption and Photoelectron Emission Experiments

Shang-Hong Cheng¹, Chien-Hung Chang², Juan-Jesus Velasco-Velez^3,4, Bo-Hong Liu^1,5*

¹Scientific Research Division, National Synchrotron Radiation Research Center, Hsinchu, Taiwan
²Experimental Facility Division, National Synchrotron Radiation Research Center, Hsinchu, Taiwan
³Department of Heterogeneous Reactions, Max Planck Institute for Chemical Energy Conversion, Mülheim an der Ruhr, Germany
⁴Experiments division, ALBA Synchrotron Light Source, Cerdanyola del Vallés, Barcelona, Spain
⁵Chemical Science Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA

* Presenter:Bo-Hong Liu, email:liu.bh@nsrrc.org.tw

X-ray irradiation can induce chemical reactions on surfaces. In X-ray spectroscopic experiments, such reactions may result in spectrum distortion and are referred to as radiation damage. In this study, we investigate the X-ray-induced chemical reaction at the partially oxidized copper surface in the settings of the dip-and-pull experiment, a widely used method that generates liquid-solid interfaces for in-situ X-ray photoelectron spectroscopy (XPS) studies.[1] In dense water vapor resembling the pre-dipping condition, a series of time-elapsed X-ray absorption spectra in total electron yield mode (TEY-XAS) shows that X-ray exposure causes copper reduction, which follows first-order kinetics and occurs only at the surface shallower than the probing depth of TEY-XAS. At the solid-water interface created by the dip-and-pull method, the chemical reduction of surface copper is also identified by XPS. We conclude that the reduction is driven by the product of water radiolysis, where the reducing solvated electron prevails against the oxidizing OH radical and results in an overall reduction of surface copper ions. This work elucidates the cause of the radiation damage and provides useful information for developing the dip-and-pull method.[2]


[1] Karslioğlu, O.; Nemšák, S.; Zegkinoglou, I.; Shavorskiy, A.; Hartl, M.; Salmassi, F.; Gullikson, E. M.; Ng, M. L.; Rameshan, C.; Rude, B.; Bianculli, D.; Cordones, A. A.; Axnanda, S.; Crumlin, E. J.; Ross, P. N.; Schneider, C. M.; Hussain, Z.; Liu, Z.; Fadley, C. S.; Bluhm, H., Faraday Discussions 2015, 180, 35-53.
[2] Cheng, S.-H.; Chang, C.-H.; Velasco-Velez, J.-J.; Liu, B.-H., Soft X-ray Induced Radiation Damage in Dip-and-Pull Photon Absorption and Photoelectron Emission Experiments. The Journal of Physical Chemistry C 2024, 128 (34), 14381-14387.

Keywords: X-ray photoelectron spectroscopy, ambient-pressure X-ray photoelectron spectroscopy, synchrotron radiation, liquid-solid interface