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. Keywords: Raman scattering, low excitation level, photooxidation, epitaxial films, lead sulfide, lead sulfide-selenide.
In recent years, carbon dots have attracted much scientific attention due to their unique properties, which can find applications in many fields. We have developed synthesis protocols of carbon dots with different structure and optical properties using o-phenylenediamine. The change in absorption and luminescence spectra of carbon dots were studied in detail. The obtained samples show intensive luminescence at 350 nm and 450 or 550 nm dependent on synthesis parameters. Keywords: Carbon dots, photoluminescence, spectroscopy.
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