Energy-synchronized X-ray absorption spectroscopy photoemission electron microscopy at Shanghai Synchrotron Radiation Facility (SSRF) for materials science.

Abstract

This study develops an integrated X-ray absorption spectroscopy (XAS) photoemission electron microscopy (PEEM) platform on beamline BL09U at the Shanghai Synchrotron Radiation Facility (SSRF), enabling nanoscale characterization of complex materials through energy-resolved imaging and local-area XAS. By using the wide range of energy tunability, full access to different polarizations and PEEM's surface sensitivity, we have established a gap-monochromator control system under the EPICS framework to synchronize the elliptically polarized undulator (EPU) gap and monochromator energy dynamically, optimizing photon flux stability for absorption fine structure analysis. Combining X-ray magnetic circular dichroism (XMCD) and X-ray magnetic linear dichroism (XMLD) with PEEM and local-area XAS, this platform achieves concurrent mapping of electronic structures and magnetic domains in ferromagnetic nano-patterns, as demonstrated through our studies of Ni₈₀Fe₂₀ Permalloy using this system. The dual-modal approach bridges synchrotron radiation technology and surface science, offering nanometre-scale spatial resolution in XAS with magnetic domain sensitivity through linearly and circularly polarized X-ray excitation, providing researchers with advanced tools for functional materials analysis through synergistic XAS-PEEM techniques and dynamic control systems.