10.48788/DVUA/JSPAOF Tkach, Vira0000-0002-2403-8607(Frantsevich Institute for Problems of Materials Science of NAS of Ukraine)O.Y. Khyzhun0000-0001-6727-643X(Frantsevich Institute for Problems of Materials Science of NAS of Ukraine)N.M. Denysіuk0000-0002-0492-1945(Frantsevich Institute for Problems of Materials Science of NAS of Ukraine)Luzhnyi Ivan Vasyliovych0000-0003-3809-7517(Frantsevich Institute for Problems of Materials Science of NAS of Ukraine) DataverseUA 2026 Experimental X-ray photoelectron spectroscopy (XPS) dataset collected for a Cs2HgI4 single crystal synthesized via the vertical Bridgman–Stockbarger method. The dataset encompasses wide-range survey energy scans, high-resolution core-level regions (Cs 3d, Hg 4f, and I 3d), as well as low-binding-energy valence-band spectra. Measurements were conducted both on the pristine surface (cleaved in ultra-high vacuum) and following surface bombardment with low-energy Ar+ ions. The deposited files include digitized numerical spectral curves and high-quality vector plots suitable for analyzing chemical states, stoichiometry, and electronic density of states. Tkach, Vira(Frantsevich Institute for Problems of Materials Science of NAS of Ukraine)Frantsevych Institute for Problems of Materials Science of NAS of Ukraine(National Academy of Sciences of Ukraine)