Effect of 231 MeV Xe-Ion Irradiation on the Structural and Luminescence Characteristics of PbWO4 Single Crystals

Undoped PbWO4 single crystals were irradiated with 231 MeV 131Xe ions at fluences of 1 × 1011 and 1 × 1013 ions cm−2 and investigated by optical absorption, Raman spectroscopy, low-temperature excitation–emission spectroscopy, photoluminescence, and room-temperature X-ray luminescence. SRIM/TRIM calculations show a strongly electronic-stopping-dominated regime (Se/Sn ≈ 258) with a projected ion range of approximately 14.36 μm. Using an effective displacement energy of 50 eV for Pb, W, and O, the calculated peak nominal ballistic damage is approximately 1.5 × 10−4 and 1.5 × 10−2 dpa at the two fluences, respectively; these values exclude electronic excitation damage. Xe irradiation produces pronounced fluence-dependent optical attenuation and shifts the operational absorption onset to lower energies. The 785 nm non-confocal, surface-focused Raman response shows no dominant PbWO4-III signature; it does not establish structural integrity throughout the Xe-modified layer. At 8 K, the excitation-action spectra broaden, and their apparent near-edge maxima shift from 4.10–4.11 eV to approximately 4.19–4.22 eV; this behavior is attributed to a combination of optical filtering, reabsorption, and excitation-dependent non-radiative competition rather than to an intrinsic shift of the electronic excitation edge. The blue host emission remains observable after irradiation, whereas long-wavelength green/yellow and red defect-related components gain relative weight. The relative integrated X-ray-luminescence output decreases strongly with increasing fluence; the stated screen-factor correction for induced absorption gives estimates of approximately 38.9% and 31.8% of the pristine value, consistent with losses beyond single-pass optical attenuation. The optical and luminescence changes are consistent with enhanced carrier trapping and non-radiative relaxation, without providing a depth-resolved structural characterization of the irradiated layer.