Multimodal soft X-ray photoelectron spectro-microscopy at the Taiwan Photon Source

Tzu-Hung Chuang^1*, Heng-Wen Wei¹, Meng-Che Wu¹, Hsin-Hao Chiu¹, Der-Hsin Wei¹

¹Scientific Research Division, National Synchrotron Radiation Research Center, Hsinchu, Taiwan

* Presenter:Tzu-Hung Chuang, email:chuang.th@nsrrc.org.tw

An imaging-type photoelectron momentum microscope (MM) recently established at the Taiwan Photon Source (TPS) 27A2 [1-2] is an ideal tool for probing advanced two-dimensional (2D) van der Waals (vdW) materials, taking advantages of the combination of direct-space and momentum-space imaging and photoelectron spectroscopy capabilities with both element- and spin-resolution.
Offline commissioning of the MM was performed using two in-house ultraviolet (UV) sources [2], and the commissioning with synchrotron soft X-rays has been initiated in mid- 2025. In this talk, the performance of the MM by measuring a standard checkerboard-patterned specimen and an Au(111) single crystal using UV sources will be first presented. By analyzing the intensity profile of the edge of the Au patterns, the Rashba-splitting of Au(111) Shockley surface state at 300 K, and the photoelectron intensity across the Fermi-edge at 80 K, the spatial, momentum, and energy resolution were estimated to be 50 nm, 0.0172 Å^-1 and 26 meV, respectively [2].
Finally, synchrotron soft X-rays have been arrived at the 27A2 end-station in mid-2025. Recent commissioning results on imaging-based X-ray photoelectron spectroscopy (XPS), X-ray absorption spectroscopy (XAS), and X-ray magnetic circular/linear dichroism (XMCD/XMLD) will be demonstrated and discussed.

References:
[1] Shiu, et. al., “When microscopy meets soft X-ray at TLS and TPS”, J. Electron Spectrosc. Relat. Phenom. 266, 147363 (2023).
[2] Chuang, et al., “Performance of a photoelectron momentum microscope in direct- and momentum-space imaging with ultraviolet photon source”, J. Synchrotron Rad. 31, 195 (2024).

Keywords: vdW 2D materials, photoelectron microscopy, XPS, XMCD