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Resonant raman scattering in CdSxSe1-x nanocrystals : effects of phonon confine...
Freitas Neto, E. S.; Silva, S. W. da; Morais, P. C.; Vasilevskiy, Mikhail; Silva, M. A. Pereira da; Dantas, N. O.Optical phonon modes confined in CdSxSe1-x nanocrystal (NC) quantum dots (≈ 2 nm in radius) grown in a glass matrix by the melting-nucleation method, were studied by means of resonant Raman scattering (RRS)spectroscopy and theoretical modelling. The formation of nanocrystalline quantum dots (QDs) is evidenced by the observation of absorption peaks and theoretically expected resonance bands in the RRS excitation...
Synthesis and characterization of PbS quantum dots embedded in oxide glass
Silva,R. S.; Monte,A.F.G.; Morais,P. C.; Alcalde,A. M.; Qu,Fanyao; Dantas,N. O.The fusion method was used to produce PbS quantum dots (QDs) embedded in S-doped glass matrix (SiO2-Na2CO3-Al2O3-PbO2-B2O3:S). Measurements of optical absorption (OA), photoluminescence (PL) and atomic force microscopy (AFM) have been carried out in order to characterize the produced QDs. A strong red-shift observed in the optical features with an increase of the annealing time indicates an increase in QD-size....
Synthesis and characterisation of CdS nanoparticles in mesoporous copolymer tem...
Monte,A. F. G.; Dantas,N. O.; Morais,P. C.; Rabelo,D.Micron-sized spheres of mesoporous styrene-divinylbenzene (Sty-DVB) copolymer were produced by suspension polymerisation in the presence of inert diluents. Using these mesoporous microspheres as a template, optically stable CdS nanoparticles have been synthesized. To characterize these CdS nanoparticles, Raman spectroscopy and micro-photoluminescence were used. We have observed enhanced emission and lasing acti...
Characterization and properties of CdO nanocrystals incorporated in polyacrylamide
Radi,P. A.; Brito-Madurro,A. G.; Madurro,J. M.; Dantas,N. O.CdO quantum dots (QDs) incorporated in polyacrylamide were synthesized adding aqueous suspension of cadmium oxide in acrylamide:bisacrylamide copolymer. Optical properties of CdO nanocrystals were studied by optical absorption. The size ranges (2-3 nm) were calculated by the effective mass approximation.
Anomalous shift of the recombination energy in single asymmetric quantum wells
Dantas,N.O.; Qu,Fanyao; Morais,P.C.Self-consistent numerical calculation and photoluminescence (PL) measurements have been used to investigate the temperature dependence of the optical Stark effect in n-doped GaAs/AlGaAs single asymmetric quantum wells (SAQWs), grown by molecular beam epitaxy. In the low-temperature regime (5 to 40 K) a remarkable blue shift (9.8 meV) is observed in the PL peak energy, as the optical excitation intensity increas...
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