The photoluminescence (PL) and photoluminescence excitation (PLE) spectra of an EFG-grown (−201) β-Ga₂O₃ single crystal were recorded at 7 and 300 K at the FinEstBeAMS beamline of the MAX IV Laboratory. Excitation–emission maps and fixed-wavelength PLE profiles covered 4.50–10.50 eV at both temperatures. Each temperature series was normalized to its own 5.00 eV intensity and, alternatively, to its own maximum; the reported ratios therefore describe excitation dependence within one series and not an absolute difference in luminescence yield between temperatures. At 7 K, integrated emission at 10.50 eV retains 95.4% of its 5.00 eV value and 89.2% of its maximum. At 300 K, the PLE half-height is 4.55 eV, and the maximum occurs at 4.75–4.80 eV, followed by a decrease to 2.26% of the 5.00 eV value and 2.03% of the maximum at 10.50 eV. Room-temperature ellipsometry on the same factory-polished face places the PLE rise in the rapidly increasing absorption region and yields a penetration depth of approximately 0.24 μm near the PLE half-height and 37 nm at 5.90 eV. A constrained depth-dependent calculation does not reproduce the full decline, so surface capture is retained as one possible pathway rather than an established mechanism. The emission is described by the same effective bands at 3.55, 3.37 and 3.07 eV used in the preceding laser study. Their balance is nearly constant at 7 K, whereas the low-energy spectral weight increases at 300 K under deep-VUV excitation. These spectra provide quantitative reference profiles for energy conversion and carrier capture in β-Ga₂O₃.

This exploratory study compares one pristine NdGaO₃(110) crystal with one crystal irradiated at 1 × 10¹¹ ions cm⁻² and one crystal irradiated at 1 × 10¹² ions cm⁻² using 147 MeV ⁸⁴Kr ions. Because each condition is represented by a single independent specimen, specimen-to-specimen variability is confounded with the irradiation condition, and no specimen-level statistical inference is made. Symmetric X-ray diffraction, condition-averaged confocal micro-Raman spectroscopy, and UV–Vis–NIR transmission were used to compare surface-normal lattice response, local vibrational line shapes, and radiation-induced optical attenuation. The nearly angle-independent XRD shift at 1 × 10¹¹ ions cm⁻² is dominated by a common angular offset, whereas the two surviving harmonics at 1 × 10¹² ions cm⁻² give a model-conditioned estimate ε₁₁₀ = +0.509 ± 0.040%. At the higher fluence, the integrated intensities captured in the coupled θ–2θ condition decrease to 9.35 ± 0.46% for (110) and 1.29 ± 0.06% for (220), while the (220) FWHM ratio reaches 7.83 ± 0.73. These fit-derived errors do not include specimen alignment or between-specimen variability. The archived condition-averaged Raman spectra retain Pbnm-like vibrational groups, while the fitted FWHM values of the 168, 214/215, and 449–470 cm⁻¹ features increase by 15.7%, 19.4%, and 14.8%. The bulk-integrated Nd³⁺ 4f–4f maxima remain stable within the wavelength sampling, whereas the effective R_p-normalized differential attenuation at 275–285 nm reaches 388.7 cm⁻¹. The data support an exploratory description of a strained and diffraction-heterogeneous crystalline layer; complete amorphization, quantitative mosaicity, a damage threshold, track dimensions, and a microscopic defect identity are not established.