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Raman scattering spectra of 1–2 μm thick n-PbS(111) epitaxial films grown by molecular beam epitaxy on BaF2(111) substrates were obtained and analyzed. The spectra were recorded at a low excitation level of 0.36 mW/μm2, which did not cause photo- and thermal degradation of the films. It is shown that, in accordance with the symmetry selection rules, the bands in the spectra correspond to overtone or combination tones of phonon modes of PbS at special points of the Brillouin zone. The analysis of the bands of oxides and oxysulfates of lead, which can mask the bands of lead sulfide, was carried out. The obtained data were used in the analysis of the recorded Raman scattering spectra by epitaxial films of a ternary solid solution PbS0.5Se0.5. [ABSTRACT FROM AUTHOR]

The Raman scattering, infrared absorption, and reflection spectra of hexagonal non-centrosymmetric BaZnBO3F and BaAlBO3F2 and centrosymmetric BaZn3BO3F2 and BaZnCO3F2 are calculated using the standard procedures of the CRYSTAL package with the basis of localized orbitals and the B3LYP hybrid functional within the framework of the Hartree-Fock conjugate perturbation method. It is shown that the layered structure of crystals manifests itself in the spectra of vibrational modes polarized along and perpendicular to the c axis with wavenumbers for the lattice region formed by displacements of atoms in [BaF]∞ and [MAO3]∞ (M: Zn, Al; A: B, C) layers, for molecular deformation outside and in the plane of anions BO3 and CO3. The quantitative and qualitative composition of the spectra is determined by the symmetry of the crystal lattice. [ABSTRACT FROM AUTHOR]

• NaPO 3 -BaF 2 -AlF 3 -CaF 2 glass doped with Tb3+ and Eu3+ was synthesized, and its structural characteristics were analyzed. • The Judd-Ofelt parameters indicate its highly asymmetric environment, which promotes the ultrasensitive transition of Eu3+ and favors the red-light emission. • The complementarity of absorption peaks makes its response to ultraviolet light cover the UVA band. • Verified the energy transfer relationship between Eu3+ and Tb3+, which is conducive to down-conversion fluorescence. • Proposed and verified a new idea to improve the utilization rate of UV light for silicon-based opto-electronic materials. In this article, NaPO 3 -BaF 2 -AlF 3 -CaF 2 glasses doped with Eu3+ and Tb3+ were manufactured by conventional melt-quenching method, and they showed good physical properties throughout various measurements: density, refractive index, Raman scattering, and X-ray diffraction (XRD). Basing on Judd-Ofelt theory, the Ω 2/4/6 values were calculated. The higher Ω 2 values of the Eu3+-doped fluorophosphate glasses indicate a highly polarized environment around Eu3+ ions. Accompanying with the Eu3+ and Tb3+ dual-doped glass, it showed that the response of excitation absorption extended by whole UVA region. This phenomenon was explained by the energy transferring between Eu3+ and Tb3+. Combining the dual-doped glass with silicon-based photodetectors, the spectral response of the detectors in the UVA region was improved up to 20%. [ABSTRACT FROM AUTHOR]