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The interest in thorough description of Zn 1– x Mn x GeAs 2 arises from its suitability for application in the field of non-linear optics. The room temperature far-infrared reflectivity spectra of single crystals Zn 1– x Mn x GeAs 2 , where 0 ≤ x ≤ 0.078, were measured in the spectral range from 80 cm −1 to 500 cm −1 . The spectra were analyzed by fitting procedure using a dielectric function which includes interaction between a plasmon and two different phonons. The detected phonons are in excellent agreement with the theoretical predictions. The MnAs cluster phonons are detected, as well. [ABSTRACT FROM AUTHOR]

Highlights: [•] Behavior of PbTe(Cr) is analyzed by galvanomagnetic and far-infrared measurements. [•] Two local modes of Cr corresponding to impurity atoms in different valence states. [•] Existence of plasmon-ionized impurity–phonon coupling in the PbTe(Cr). [•] We compute Fermi level vs. temperature and confirm its stabilization by experiment. [•] We determine that n-type PbTe(Cr) crystals has persistent conductivity. [ABSTRACT FROM AUTHOR]

Highlights: [•] CdTe SAQD diameter obtained to be 4.3nm. [•] Direct deexcitation to ground state. [•] Optical phonon assisted deexcitation. [•] Existence of surface optical phonon. [•] Multiphonon processes depend on temperature and excitation energy. [ABSTRACT FROM AUTHOR]

Abstract: We have synthesized CdS and Cd0.7Mn0.3S nanocrystals with diameters of about 4.5nm. These materials have been studied using photoluminescence spectroscopy with various excitation energies in the temperature range from 1.8 to 300K. We registered surface and defect states as well as two Mn2+ energy levels that correspond to Mn2+ ions in two different crystal environments. In addition, the resonant behavior of one Mn state excited by 514.5nm wavelength of laser light has been clearly observed in obtained spectra. We proposed the scheme of energy levels and transitions that explain obtained experimental results. [Copyright &y& Elsevier]

The nanopowders of (ZnO) 1– x (Al2O3) x , where x ranges from 0 to 0.7, were obtained by two chemical methods: the co-precipitation/calcination and hydrothermal synthesis. The first assessment of structural and optical properties of the obtained nanopowders was undertaken by the SEM, XRD, Raman and far-infrared spectroscopy, which was followed by the photoluminescence spectroscopy at room temperature. The obtained far-infrared reflectivity spectra were analyzed using the fitting procedure. The dielectric function of ZnO–Al 2 O 3 nanopowders was modeled by the Maxwell-Garnet formula under the assumption that the nanopowders are a mixture of homogenous spherical inclusions in air. The combined plasmon-LO phonon modes (CPPM) were observed in the far-infrared reflection spectra. The photoluminescence spectra contain emissions related to the presence of ZnO, ZnAl 2 O 4 , and AlOOH phases in the nanomaterial, which is in agreement with the results obtained by other experiments. Image 1 • ZnO–Al 2 O 3 samples prepared by coprecipitation-calcination and hydrothermal method. • Samples characterized by SEM, XRD, photoluminescence and far infrared spectroscopy. • ZnAl 2 O 4 and ZnO phases are present. • Combined plasmon-LO phonon modes are registered. • PL measurements of samples Al 2 O 3 content between 20% and 40% revealed complex spectra. [ABSTRACT FROM AUTHOR]

We have studied optical, electrical and structural properties of the semimagnetic semiconducting ZnGeAs 2 crystals, undoped and doped with 1.5, 3 and 3.5 wt% Mn, which is perspective material for spintronics. We used Raman spectroscopy as a sensitive method for precise determination of crystal structure. In addition to the vibrational frequencies of a ZnGeAs 2 lattice, MnAs clusters and Mn complexes, which we have already experimentally registered at similar materials, the existence of As clusters in this material is revealed for the first time. Based on the obtained results we concluded that arsenic clusters of various sizes exist, including form of molecules – As 4 . We assume that they are located in the vicinity of the grain boundaries and that the distribution of free carriers in the samples was inhomogeneous. [ABSTRACT FROM AUTHOR]

Abstract: The properties of CdS thin films were investigated by applying atomic force microscopy (AFM), Raman and far-infrared spectroscopy. CdS thin films were prepared by using the thermal evaporation technique under base pressure 2×10−5 torr. The quality of these films was investigated by AFM spectroscopy. We applied Raman scattering and far-infrared spectroscopy to investigate the optical properties of CdS thin films, and reveal the existence of Surface Optical Phonon (SOP) mode at 297cm−1. Effective permittivity of mixture was modeled by Maxwell–Garnet approximation. In the analysis of the far-infrared reflection spectra, a numerical model for calculating the reflectivity coefficient for a system which includes films and substrate was applied. [Copyright &y& Elsevier]

The far-infrared spectroscopy was used to analyze optical properties of PbTe single crystals doped with different amounts of Si. A dielectric function that takes into account the plasmon-phonon interaction was employed in the measured data manipulation. Two frequencies of plasmon-phonon coupled modes were obtained with the best-fit method, whereas the values for LO mode and plasma frequency (ω P) were calculated. The best-fit to the experimentally obtained spectra agrees very well with the theoretical prediction. Image 1 • Single crystals PbTe(Si) were grown by the modified Bridgman method. • Optical properties were investigated applying Far-infrared spectroscopy. • Plasmon–phonon coupling is registered. • Localization of electrons in the vicinity of Si impurity atom is observed. [ABSTRACT FROM AUTHOR]

Abstract Structural and optical properties of CdTe thin films were investigated applying atomic force microscopy (AFM), XRD powder technique, Raman spectroscopy and far–infrared spectroscopy. CdTe thin films were prepared by using thermal evaporation technique. In the analysis of the far – infrared reflection spectra, numerical model for calculating the reflectivity coefficient for system which includes films and substrate has been applied. Effective permittivity of film mixture (CdTe and air) was modeled by Maxwell – Garnet approximation. We reveal the existence of surface optical phonon (SOP) mode and coupled plasmon-SOP modes (CPSOPM). Graphical abstract Image 1 Highlights • Modified surface optical phonon – plasmon interaction in CdTe thin films registered for the first time. • Detailed analysis of surface optical phonon dependence on filling factor presented. • Beside characteristic CdTe modes, a mode with 7 cm−1 shift when compared to bulk CdTe obtained. • When prepared by thermal evaporation technique, the best quality thin films are obtained. [ABSTRACT FROM AUTHOR]

The analysis of the optical properties of mechanochemically synthesized stannite Cu 2 FeSnS 4 nanocrystals has been performed using far-infrared spectroscopy. The Cu 2 FeSnS 4 stannite nanocrystals were synthesized mechanochemically from elemental precursors Cu, Fe, Sn, and S. Milling time was 45, 60, 90 and 120 min. Reflectivity spectra were analyzed using the classical form of the dielectric function, which includes the phonon and the free carrier contribution. The influence of milling time on synthesis of stannite Cu 2 FeSnS 4 is observed. Among the modes that are characteristic for the stannite Cu 2 FeSnS 4 , we registered the modes of binary phases of FeS and SnS. The total disappearance of the binary phases of FeS and SnS and forming pure Cu 2 FeSnS 4 is observed when the milling time is 120 min. Effective permittivity of Cu 2 FeSnS 4 and binary phases of FeS and SnS were modeled by Maxwell – Garnet approximation. [ABSTRACT FROM AUTHOR]

The Raman spectra of Eu 3+ doped Gd 2 Zr 2 O 7 nanopowders were measured. We registered three phonons at 177 cm −1 , 268 cm −1 , and 592 cm −1 , as well as their overtones at 354 cm −1 , 445 cm −1 , 708 cm −1 , 1062 cm −1 , 1184 cm −1 , ∼1530 cm −1 , and ∼1720 cm −1 . The phonon at 592 cm −1 is known to be characteristic for Gd 2 Zr 2 O 7 fluorite-type structure; however, the other two have not been registered so far. We found that the position of the newly detected phonons agrees well with the observed electron-phonon interaction. On the other hand, the registered multiphonon processes were a consequence of miniaturization that further induced changes in electronic structure of Eu 3+ doped Gd 2 Zr 2 O 7 nanopowders. [ABSTRACT FROM AUTHOR]

Metal complexes with some Schiff bases, as one of the most widely used groups of ligands, have a wide field of application. In order to find a material with the required optical properties, it is very important to examine the material characteristics as a function of the type of chelating ligand, metal, and the ions present as coligands. In this paper, the synthesis of two new complexes of 2-acetylpyridine-aminoguanidine (L) with zinc(II) and cadmium(II), viz. [Zn(L)(NCO) 2 ] and [{Cd(L)Cl(μ-NCO)} 2 ] is described. Their structural characterization was provided by using SC-XRD. Spectroscopic characterization of these two new complexes and two previously synthesized complexes - [Zn(L)(NSC) 2 ] and [Cd(L)Cl 2 ] are performed. Their phonon structure was determined based on the IR transmission and Raman spectra. The range of Raman modes with significantly increased intensities was registered (1000-1700 cm−1), the same range for all four samples. Also, the registered photoluminescence and energy transfers were analyzed and three photoluminescence peaks (E 1 , E 2 , E 3) were determined. It was concluded that phonons with significantly increased intensities participate in transitions from the E 1 state to the energy levels in the range from E 2 to E 3. The strength of the peaks was significantly affected by replacing one [Cl]- with the [NCO]- ligand. The addition of the second [NCO]- ligand increases the photoluminescence over the entire measured range. The analysis performed helps to understand the issues related to the electron-phonon interaction. Also, the perspectives for the application of metal complexes with various ligands are expanding. [Display omitted] • Synthesis of two new complexes [ZnL((NCO) 2 ] and [{Cd(L)Cl(μ-NCO)} 2 ] is described. • Phonons in the range 1000-1700 cm−1 are significantly increased on the Raman spectra. • These phonons participate in the energy transitions by electron-phonon interaction. • The photoluminescence was significantly affected by addition of [NCO]- ligand. • Electron-phonon interaction were analyzed, specifically Phonon assisted charge transfer. [ABSTRACT FROM AUTHOR]

In this paper we describe the synthesis and characterization of the YVO 4 :Eu 3+ nanopowder. The material was prepared using simple solution combustion synthesis. X-ray powder diffraction (XRD), scanning electron microscope (SEM), Raman and photoluminescence (PL) techniques were used to confirm and characterize the prepared material. The time resolved analysis of emission spectra was achieved by using the streak camera system. Beside luminescence lifetime of slow decayed transitions we also measured their rise time and lifetime of fast decayed transitions. We also determined the excitation spectra of this nano material. Results of our analysis prove that YVO 4 :Eu 3+ nanopowder is appropriate material for various optoelectronic devices. [ABSTRACT FROM AUTHOR]

Dysprosium (Dy 3+ ions) doped YAG nanopowders were prepared by the solution combustion synthesis (SCS) method and undoped yttrium aluminum garnet (YAG, Y 3 Al 5 O 12 ) single crystal was grown by the Czochralski technique. The structure of the prepared materials has been confirmed and characterized using X-ray powder diffraction (XRD), scanning electron microscope (SEM), Raman and photoluminescence (PL) spectroscopy. PL spectra were acquired using Optical Parametric Oscillator (OPO) excitation tuned at 350 nm. Several emission bands in Dy 3+ emission spectrum were observed in the blue (470–500 nm), yellow (560–600 nm), red (660–685 nm) and infra-red (750–780 nm) regions, corresponding to 4 F 9/2 – 6 H 15/2 , 4 F 9/2 – 6 H 13/2 , 4 F 9/2 – 6 H 11/2 , 4 F 9/2 –( 6 H 9/2 + 6 H 11/2 ) transitions in the 4f levels of Dy 3+ ions, respectively. By using the Commission Internationale de l’Eclairage (CIE) chromaticity diagram of emission spectra it has been shown that this material can be used as a source of a white light. The result of lifetime analysis of the 4 F 9/2 level in dysprosium ion has been reported, as well. [ABSTRACT FROM AUTHOR]

Nanopowders based on gadolinium zirconium oxide (Gd 2 Zr 2 O 7 ) doped by europium ions (Eu 3+ ) were successfully prepared using a flame combustion method. This material is suitable for various optical devices. The structure of prepared materials has been confirmed and characterized using X-ray powder diffraction (XRD), scanning electron microscope (SEM) and photoluminescence (PL) techniques. The luminescence properties of synthesized nanopowders were characterized by emission spectra and luminescence lifetimes by using the streak camera system. PL spectra were obtained at three different excitation wavelengths (Optical Parametric Oscilator (OPO) at 360 nm, laser diode at 365 nm and Ar laser line at 514.5 nm). The strong emission lines at 611 nm and 630 nm corresponding to the 5 D 0 → 7 F 2 long lived transition could be used as a new red light source in optical devices. [ABSTRACT FROM AUTHOR]

Highlights: [•] Composite films PMMA–(BSO) were processed by dispersion casting method. [•] The refractive index increased in composites with higher BSO content. [•] Tg of the composites was slightly higher than for pure PMMA. [•] The addition of BSO to the polymer increased modulus of elasticity and hardness. [ABSTRACT FROM AUTHOR]

Low-k materials such as silicon dioxide (SiO2) play an important role in the semiconductor industry. Plasma has become indispensable for advanced materials processing. In this work a treatment of SiO2 single crystal by direct current plasma discharge is studied in detail. Offline metrology is conducted for silicon dioxide wafers by Raman scattering, energy-dispersive x-ray spectroscopy, and ellipsometry. Broad Raman peak at around 2800 cm-1 is observed for the treated SiO2 wafers. Effects of plasma treatment on position of this peak are reported in the paper. An analysis of this correlation could be a framework for creating virtual etch rate sensors, which might be of importance in managing plasma etching processes. [ABSTRACT FROM AUTHOR]

In this paper we present photoluminescence measurements of CdSe nanoparticles embedded in transparent glass. Sample is prepared using an original technique, which combines both heat treatment and ultraviolet laser irradiation. Photoluminescence spectra displayed one main emission band at 2.14 eV. We identify this bands energy as basic interband transition in CdSe nanoparticle. We calculated energy of basic (1sh-1se) transition in spherical CdSe quantum dot (QD), within infinite potential barrier, in effective-mass approximation. On the basis of this model, average radius of synthesized CdSe QDs is about 3 nm, which is in consistence with AFM measurements and UV-VIS absorption measurements. [ABSTRACT FROM AUTHOR]