Raman investigation on thin and thick CdTe films obtained by close spaced vacuum sublimation technique

The CdTe thin and thick films were obtained by the close spaced vacuum sublimation technique on a glass substrate under the following growth conditions: the evaporator temperature was 620 °C; and the substrate temperature was varied in the range from 250 °C to 550 °C. High purity CdTe powder was used as a charge for evaporation. The Raman spectra were measured using TRIAX 320 and TRIAX 550 spectrometers at room temperature. The 488-nm line and 514.5-nm line of an Ar+ laser and a 785-nm diode laser were used as excitation sources. The signal was collected by the liquid nitrogen cooled chargecoupled-device (CCD) detector. A number of intense Raman peaks at 140, 167, 190, 271, 332 and 493 cm-1 were observed and were interpreted as TO (140 cm-1), 1LO (167 cm-1), 2LO (332 cm-1), 3LO (493 cm-1) phonon modes and plasmon-phonon mode (190 cm-1). The presence of several phonon replicas in the Raman spectra confirms high crystal quality of the samples. When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/37061This work is supported by the Ukraine State Agency for the Science, Innovation, and Informatization and by the NRF grant funded by the MEST of Korea (2011-0019204) and by the Ministry of Education and Science of Ukraine

Composition variations in Cu2ZnSnSe4 thin films analyzed by X-ray diffraction, energy dispersive X-ray spectroscopy, particle induced X-ray emission, photoluminescence, and Raman spectroscopy

Compositional and structural studies of Cu2ZnSnSe4 (CZTSe) thin films were carried out by X-ray diffraction, energy dispersive X-ray spectroscopy (EDS), particle induced X-ray emission (PIXE), photoluminescence, and Raman spectroscopy. CZTSe thin films with different compositions were deposited on sodalime glass by coevaporation. The composition of the filmsmeasured by two differentmethods, EDS and PIXE, showed significant differences. Generally, the Zn/Sn ratio measured by EDS is larger than that measured by PIXE. Both the micro- PIXE and the micro-Raman imaging results indicated the compositional and structural inhomogeneity of the sample. When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/37033This researchwas supported by the International Research&Development Program of the National Research Foundation of Korea funded by theMinistry of Science, ICT and Future Planning of Korea (Grant number: 2011-0019204) and by the New & Renewable Energy of the Korea Institute of Energy Technology Evaluation and Planning grant funded by the Korea government’s Ministry of Trade, Industry and Energy (No. 20123010010130)

Composition variations in Cu2ZnSnSe4 thin films analyzed by X-ray diffraction, energy dispersive X-ray spectroscopy, particle induced X-ray emission, photoluminescence, and Raman spectroscopy

Compositional and structural studies of Cu2ZnSnSe4 (CZTSe) thin films were carried out by X-ray diffraction, energy dispersive X-ray spectroscopy (EDS), particle induced X-ray emission (PIXE), photoluminescence, and Raman spectroscopy. CZTSe thin films with different compositions were deposited on sodalime glass by coevaporation. The composition of the filmsmeasured by two differentmethods, EDS and PIXE, showed significant differences. Generally, the Zn/Sn ratio measured by EDS is larger than that measured by PIXE. Both the micro- PIXE and the micro-Raman imaging results indicated the compositional and structural inhomogeneity of the sample. When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/37033This researchwas supported by the International Research&Development Program of the National Research Foundation of Korea funded by theMinistry of Science, ICT and Future Planning of Korea (Grant number: 2011-0019204) and by the New & Renewable Energy of the Korea Institute of Energy Technology Evaluation and Planning grant funded by the Korea government’s Ministry of Trade, Industry and Energy (No. 20123010010130)

Influence of deposition conditions on morphological, structural, optical and electro-physical properties of ZnSe films obtained by close-spaced vacuum sublimation

ZnSe thin films were deposited on well-cleaned glass substrates by the close-spaced vacuum sublimation technique. Various structural, sub-structural and optical properties have been investigated through scanning electron microscopy (SEM), X-ray diffraction (XRD), spectral photometry, Raman spectroscopy and Fourier transform infrared (FTIR) spectroscopy. Electro-physical studies were performed using an ITO/ZnSe/In “sandwich” structure.The correlation between the films structure and their optical and electro- physical properties was estimated. The evaluated films were fine-crystalline, with their grain size depending on the substrate temperature. The optical band gap was estimated through optical measurements and the high optical qualities of the ZnSe films were confirmed by Raman and FTIR analyses.This work is supported by the Ukraine State Agency for the Science, Innovation and Informatization and by the NRF grant funded by the MSIP of Korea (2011–0019204) and by the Ministry of Education and Sciences of Ukraine (Grant no.0113U000131)

Influence of deposition conditions on morphological, structural, optical and electro-physical properties of ZnSe films obtained by close-spaced vacuum sublimation

ZnSe thin films were deposited on well-cleaned glass substrates by the close-spaced vacuum sublimation technique. Various structural, sub-structural and optical properties have been investigated through scanning electron microscopy (SEM), X-ray diffraction (XRD), spectral photometry, Raman spectroscopy and Fourier transform infrared (FTIR) spectroscopy. Electro-physical studies were performed using an ITO/ZnSe/In “sandwich” structure.The correlation between the films structure and their optical and electro- physical properties was estimated. The evaluated films were fine-crystalline, with their grain size depending on the substrate temperature. The optical band gap was estimated through optical measurements and the high optical qualities of the ZnSe films were confirmed by Raman and FTIR analyses.This work is supported by the Ukraine State Agency for the Science, Innovation and Informatization and by the NRF grant funded by the MSIP of Korea (2011–0019204) and by the Ministry of Education and Sciences of Ukraine (Grant no.0113U000131)

Raman investigation on thin and thick CdTe films obtained by close spaced vacuum sublimation technique

The CdTe thin and thick films were obtained by the close spaced vacuum sublimation technique on a glass substrate under the following growth conditions: the evaporator temperature was 620 °C; and the substrate temperature was varied in the range from 250 °C to 550 °C. High purity CdTe powder was used as a charge for evaporation. The Raman spectra were measured using TRIAX 320 and TRIAX 550 spectrometers at room temperature. The 488-nm line and 514.5-nm line of an Ar+ laser and a 785-nm diode laser were used as excitation sources. The signal was collected by the liquid nitrogen cooled chargecoupled-device (CCD) detector. A number of intense Raman peaks at 140, 167, 190, 271, 332 and 493 cm-1 were observed and were interpreted as TO (140 cm-1), 1LO (167 cm-1), 2LO (332 cm-1), 3LO (493 cm-1) phonon modes and plasmon-phonon mode (190 cm-1). The presence of several phonon replicas in the Raman spectra confirms high crystal quality of the samples. When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/37061This work is supported by the Ukraine State Agency for the Science, Innovation, and Informatization and by the NRF grant funded by the MEST of Korea (2011-0019204) and by the Ministry of Education and Science of Ukraine

Davydov Splitting and Excitonic Resonance Effects in Raman Spectra of Few-Layer MoSe₂

Raman spectra of few-layer MoSe₂ were measured with eight excitation energies. New peaks that appear only near resonance with various exciton states are analyzed, and the modes are assigned. The resonance profiles of the Raman peaks reflect the joint density of states for optical transitions, but the symmetry of the exciton wave functions leads to selective enhancement of the A_1g mode at the A exciton energy and the shear mode at the C exciton energy. We also find Davydov splitting of <i>intra</i>layer A_1g, E_1g, and A_2u modes due to <i>inter</i>layer interaction for some excitation energies near resonances. Furthermore, by fitting the spectral positions of <i>inter</i>layer shear and breathing modes and Davydov splitting of <i>intra</i>layer modes to a linear chain model, we extract the strength of the <i>inter</i>layer interaction. We find that the second-nearest-neighbor interlayer interaction amounts to about 30% of the nearest-neighbor interaction for both in-plane and out-of-plane vibrations

Amyloid Beta-Mediated Epigenetic Alteration of Insulin-Like Growth Factor Binding Protein 3 Controls Cell Survival in Alzheimer's Disease

<div><p>Swedish double mutation (KM670/671NL) of amyloid precursor protein (APP) is reported to increase toxic amyloid β (Aβ) production via aberrant cleavage at the β-secretase site and thereby cause early-onset Alzheimer's disease (AD). However, the underlying molecular mechanisms leading to AD pathogenesis remains largely unknown. Previously, our transcriptome sequence analyses revealed global expressional modifications of over 600 genes in APP-Swedish mutant-expressing H4 (H4-sw) cells compared to wild type H4 cells. Insulin-like growth factor binding protein 3 (<i>IGFBP3</i>) is one gene that showed significantly decreased mRNA expression in H4-sw cells. In this study, we investigated the functional role of <i>IGFBP3</i> in AD pathogenesis and elucidated the mechanisms regulating its expression. We observed decreased <i>IGFBP3</i> expression in the H4-sw cell line as well as the hippocampus of AD model transgenic mice. Treatment with exogenous IGFBP3 protein inhibited Aβ_{1<b>–</b>42}- induced cell death and caspase-3 activity, whereas siRNA-mediated suppression of IGFBP3 expression induced cell death and caspase-3 cleavage. In primary hippocampal neurons, administration of IGFBP3 protein blocked apoptotic cell death due to Aβ_{1<b>–</b>42} toxicity. These data implicate a protective role for IGFBP3 against Aβ_{1<b>–</b>42}-mediated apoptosis. Next, we investigated the regulatory mechanisms of IGFBP3 expression in AD pathogenesis. We observed abnormal <i>IGFBP3</i> hypermethylation within the promoter CpG island in H4-sw cells. Treatment with the DNA methyltransferase inhibitor 5-aza-2′-deoxycytidine restored <i>IGFBP3</i> expression at both the mRNA and protein levels. Chronic exposure to Aβ_{1<b>–</b>42} induced <i>IGFBP3</i> hypermethylation at CpGs, particularly at loci −164 and −173, and subsequently suppressed <i>IGFBP3</i> expression. Therefore, we demonstrate that expression of anti-apoptotic <i>IGFBP3</i> is regulated by epigenetic DNA methylation, suggesting a mechanism that contributes to AD pathogenesis.</p></div

IGFBP3 protects cells from Aβ_1–42 induced apoptosis H4 and H4-sw cells were treated for 24 h in serum-free media (SF) with 5 µM soluble Aβ₁_–42 in the presence or absence of exogenous recombinant human IGFBP3 (BP3) protein.

<p><i>IGFBP3</i> knockdown H4 cells generated by siRNA transfection or non-targeted siRNA-transfected H4 cells were treated with or without 5 µM soluble Aβ_{1<b>–</b>42} in SF media for 24 h. Apoptosis was evaluated after propidium iodide staining using FACS analyses. Compiled FACS results from three independent experiments are graphically illustrated in (A) and (B). Caspase 3 activation was examined in H4 cells by detecting cleaved forms of caspase 3 using western blot analyses. Representative results are illustrated and graphical values from densitometric analyses after normalization to β-actin are reported as relative values to that of untreated control (C). Rat hippocampal neuronal primary cells in supplements-free media were treated for 24 h with 500 nM oligomeric Aβ_{1<b>–</b>42} in the presence or absence of exogenous recombinant human IGFBP3 (BP3) protein. Caspase 3 activation was determined by detecting cleaved forms of caspase 3 using western blot analyses (D). Data are the mean ± SD of three independent experiments. Statistical analyses were performed using two-way analysis of variance (ANOVA) and Bonferroni post-tests. * indicates p<0.05. H4-sw, APP-Swedish mutant H4 cells; BP3, IGFBP3; siNC, non-targeting siRNA; siBP3, IGFBP3 siRNA.</p