8,724 results on '"blueshift"'
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2. Blueshift of the CN stretching vibration of acetonitrile in solution: computational and experimental study.
- Author
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Muniz‐Miranda, Francesco, Pedone, Alfonso, and Menziani, Maria Cristina
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POLAR molecules , *ACETONITRILE , *ELECTRIC charge , *ELECTRIC displacement , *VIBRATIONAL spectra - Abstract
Acetonitrile, a polar molecule that cannot form hydrogen bonds on its own, interacts with solvent molecules mainly through the lone pair of its nitrogen atom and the π electrons of its CN triple bond [Correction added on 17 July 2024, after first online publication: Acetole has been changed to Acetonitrile in the preceeding sentence.]. Interestingly, acetonitrile exhibits an unexpected strengthening of the triple bond's force constant in an aqueous environment, leading to an upshift (blueshift) in the corresponding stretching vibration: this effect contrasts with the usual consequence of hydrogen bonding on the vibrational frequencies of the acceptor groups, that is, frequency redshift. This investigation elucidates this phenomenon using Raman spectroscopy to examine the behavior of acetonitrile in organic solvent, water, and silver ion aqueous solutions, where an even more pronounced upshift is observed. Raman spectroscopy is particularly well suited for analyzing aqueous solutions due to the minimal scattering effect of water molecules across most of the vibrational spectrum. Computational approaches, both static and dynamical, based on Density Functional Theory and hybrid functionals, are employed here to interpret these findings, and accurately reproduce the vibrational frequencies of acetonitrile in different environments. Our calculations also allow an explanation for this unique behavior in terms of electric charge displacements. On the other hand, the study of the interaction of acetonitrile with water molecules and metal ions is relevant for the use of this molecule as a solvent in both chemical and pharmaceutical applications. [ABSTRACT FROM AUTHOR]
- Published
- 2024
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3. Modulating low-frequency tribocatalytic performance through defects in uni-doped and bi-doped SrTiO3
- Author
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Yijing Xu, Yingzhi Meng, Xu Xiang, Qing Tang, Hongfang Zhang, Laijun Liu, Ju Gao, Bo Xu, Renhong Liang, Longlong Shu, Yanmin Jia, and Wanping Chen
- Subjects
tribocatalysis ,srtio3 (sto) ,doping-induced defects ,blueshift ,flexoelectric field ,Clay industries. Ceramics. Glass ,TP785-869 - Abstract
Triboelectrification, a process that transforms mechanical energy into electrical energy through friction, holds promise for eco-friendly wastewater treatment. This study delves into the enhancement of tribocatalytic dye degradation using SrTiO3, a material notable for its non-piezoelectric and centrosymmetric properties. The synthesis of uni- and bi-doped SrTiO3 particles, achieved through a solid-state reaction at 1000 °C, results in a high-purity cubic perovskite structure. Doping with rhodium (Rh) and carbon (C) causes crystal lattice contraction, internal stress, and significant oxygen vacancies. These changes notably improve tribocatalytic efficiency under solar irradiation, with Rh-doped SrTiO3 demonstrating an impressive degradation rate of approximately 88% for Rhodamine B (RhB), along with reaction rate constants near 0.9 h−1 at 554 nm and a noticeable blueshift. This study highlights that defects introduced by doping are integral to this process, boosting catalytic activity through energy state modification and enhancing surface redox radical production. Additionally, these defects are instrumental in generating a flexoelectric field, which markedly influences the separation of electron–hole pairs under solar irradiation. Our findings illuminate the complex interplay between material composition, defect states, and environmental conditions, paving the way for advanced strategies in environmental remediation through optimized tribocatalytic activity.
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- 2024
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4. CdTe nanocrystals doped with Sm3+: blueshift and enhanced emission.
- Author
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Gao, Junfang, Xu, Shixun, Zhang, Li, Hu, Gang, Shi, Shenggang, Liu, Lu, and Yang, Junhong
- Subjects
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X-ray powder diffraction , *TRANSMISSION electron microscopy , *EMISSION spectroscopy , *OPTICAL properties , *NANOCRYSTALS - Abstract
This work used an aqueous-phase method to prepare Sm-doped CdTe nanocrystals (NCs). The successful doping of Sm into the CdTe lattice was confirmed by powder X-ray diffraction (PXRD), transmission electron microscopy (TEM), as well as UV–Visible (UV–Vis) absorption and emission spectroscopies. The CdTe and CdTe:Sm NCs are monodispersed as uniform spherical nanocrystals with cubic structures. The particle diameters are ∼4.2, ∼3.3, and ∼2.6 nm for CdTe, CdTe:Sm(5%) and CdTe:Sm(10%) NCs, respectively. Compared with pure CdTe, the CdTe:Sm(5%) NCs exhibit a blueshift of 9–23 nm in their absorption bands and a blueshift of 8–17 nm in their emission bands. With increasing concentration of Sm3+, the quantum yield (QY) of the CdTe:Sm NCs increases initially and then decreases. The CdTe:Sm NCs have longer fluorescence lifetimes than CdTe, probably due to the introduction of trap states. Due to charge compensation, the CdTe:Sm NCs have much stronger emission peaks. [ABSTRACT FROM AUTHOR]
- Published
- 2024
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5. Phenyl Derivatives Modulate the Luminescent Properties and Stability of CzBTM-Type Radicals.
- Author
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Gou, Quanquan, Guan, Jiahao, Zhang, Lintao, and Ai, Xin
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RADICALS (Chemistry) , *MOLECULAR structure , *MOLECULAR orbitals , *CARBAZOLE derivatives , *PHENYL group , *CARBAZOLE - Abstract
The distinctive electron structures of luminescent radicals offer considerable potential for a diverse array of applications. Up to now, the luminescent properties of radicals have been modulated through the introduction of electron-donating substituents, predominantly derivatives of carbazole and polyaromatic amines with more and more complicated structures and redshifted luminescent spectra. Herein, four kinds of (N-carbazolyl)bis(2,4,6-tirchlorophenyl)-methyl (CzBTM) radicals, Ph2CzBTM, Mes2CzBTM, Ph2PyIDBTM, and Mes2PyIDBTM, were synthesized and characterized by introducing simple phenyl and 2,4,6-trimethylphenyl groups to CzBTM and PyIDBTM. These radicals exhibit rare blueshifted emission spectra compared to their parent radicals. Furthermore, modifications to CzBTM significantly enhanced the photoluminescence quantum yields (PLQYs), with a highest PLQY of 21% for Mes2CzBTM among CzBTM-type radicals. Additionally, the molecular structures, photophysical properties of molecular orbitals, and stability of the four radicals were systematically investigated. This study provides a novel strategy for tuning the luminescent color of radicals to shorter wavelengths and improving thermostability. [ABSTRACT FROM AUTHOR]
- Published
- 2024
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6. Pulse‐Modulation Controllable Monolithic Full‐Color Semipolar GaN‐based Light Emitting Diodes.
- Author
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Lee, Gun‐Woo, Oh, Jae‐Hyeok, and Lee, Sung‐Nam
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LIGHT emitting diodes , *PULSE amplitude modulation , *PULSE width modulation , *CRYSTAL defects , *EMISSION control , *COLOR temperature - Abstract
Monolithic multi‐color light‐emitting diodes (LEDs) offer numerous advantages as multi‐functional lighting sources. However, the achievement of full‐color monolithic LEDs spanning from red to blue wavelengths is limited by the InN‐GaN material system. To overcome this limitation, this work demonstrates a new approach using hexagonal epitaxial lateral overgrowth to reduce the density of crystal defects and form micro‐surface structures. By utilizing arrowhead‐like surfaces in semipolar GaN films, indium incorporation can be controlled, leading to larger band‐filling effects and enabling full‐color red, green, and blue emissions from a single LED. Nonetheless, the red emission in monolithic full‐color LEDs is weaker than the blue emission due to the band‐filling induced blueshift that occurs with increasing current injection. To address this issue, pulse amplitude modulation and pulse width modulation modes are introduced to control the emission intensity from red to blue wavelengths. As a result, the study achieves a monolithic trichromatic white LED with color coordinates of (0.2985, 0.3948) and a color temperature of ≈6700 K by simultaneously emitting red, green, and blue LEDs with the same emission intensities. This achievement holds great promise for the development of high‐performance full‐color LEDs for multifunctional lighting sources that can span red, green, and blue wavelengths. [ABSTRACT FROM AUTHOR]
- Published
- 2023
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7. Doppler Effects, Redshifts, and Blueshifts
- Author
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Andrews, Steven S. and Andrews, Steven S.
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- 2023
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8. Multistimuli‐Responsive Luminescence of o‐Carborane Dyads via Restriction of Electron Transfer and Molecular Motion.
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Shen, Yunxia, Wang, Lingrui, Fang, Yuanyuan, Sui, Laizhi, Fu, Zhiyuan, Lv, Chunyan, Wang, Kai, Zhang, Qing, Guo, Haizhong, and Zhang, Yujian
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CHARGE exchange , *OPTICAL disk drives , *LUMINESCENCE , *PHOTOINDUCED electron transfer , *DYADS - Abstract
The striking change in the emission color/intensity of piezochromic luminescent materials in response to external mechanical stimuli (e.g., pressure, grinding, and stretching) has attracted attention due to potential applications in optical data storage devices, pressure sensors, and optoelectronic devices. The majority of organic materials show redshifted and quenched emission with increasing pressure. Herein, covalently linked donor/acceptor (D/A) o‐carborane dyads that exhibit dual luminescence peaks due to the occurrence of photoinduced electron transfer (PET) are reported. Interestingly, an anomalous phenomenon of pressure‐induced blueshifted and enhanced luminescence is clearly observed. From 1 atm to 1.09 GPa, the restriction of intramolecular motion increases the luminescence of o‐carborane dyads. At high pressures, the compressed o‐carborane unit suppresses PET and decreases the energy gap between the upper excited states. Since the rate of the internal conversion (IC) process is higher than that of PET, the charge transfer (CT) emission gradually disappears, causing the o‐carborane dyads to exhibit blueshifted luminescence. Therefore, a novel strategy for achieving the pressure‐induced enhanced and blueshifted luminescence characteristics of organic materials is reported in this work. [ABSTRACT FROM AUTHOR]
- Published
- 2023
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9. Introducing Spiro‐locks into the Nitrogen/Carbonyl System towards Efficient Narrowband Deep‐blue Multi‐resonance TADF Emitters.
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Yu, You‐Jun, Feng, Zi‐Qi, Meng, Xin‐Yue, Chen, Long, Liu, Fu‐Ming, Yang, Sheng‐Yi, Zhou, Dong‐Ying, Liao, Liang‐Sheng, and Jiang, Zuo‐Quan
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DELAYED fluorescence , *QUANTUM efficiency , *INTERMOLECULAR interactions - Abstract
The current availability of multi‐resonance thermally activated delayed fluorescence (MR‐TADF) materials with excellent color purity and high device efficiency in the deep‐blue region is appealing. To address this issue in the emerged nitrogen/carbonyl MR‐TADF system, we propose a spiro‐lock strategy. By incorporating spiro functionalization into a concise molecular skeleton, a series of emitters (SFQ, SOQ, SSQ, and SSeQ) can enhance molecular rigidity, blue‐shift the emission peak, narrow the emission band, increase the photoluminescence quantum yield by over 92 %, and suppress intermolecular interactions in the film state. The referent CZQ without spiro structure has a more planar skeleton, and its bluer emission in the solution state redshifts over 40 nm with serious spectrum broadening and a low PLQY in the film state. As a result, SSQ achieves an external quantum efficiency of 25.5 % with a peak at 456 nm and a small full width at half maximum of 31 nm in a simple unsensitized device, significantly outperforming CZQ. This work discloses the importance of spiro‐junction in modulating deep‐blue MR‐TADF emitters. [ABSTRACT FROM AUTHOR]
- Published
- 2023
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10. Comparative investigation of structural, photoluminescence, and magnetic characteristics of MxSn1−xOy nanocomposites.
- Author
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Sedky, A., Hakamy, A., Afify, Naser, Bouhmaidi, Soukaina, Setti, Larbi, Hamad, D., and Abd-Elnaiem, Alaa M.
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- *
MAGNETIC anisotropy , *ENERGY dispersive X-ray spectroscopy , *NANOCOMPOSITE materials , *PHOTOLUMINESCENCE , *YOUNG'S modulus , *MAGNETIC fields - Abstract
The structural parameters, photoluminescence (PL), and magnetic characteristics of MxSn1−xOy (M/SnO2) nanocomposites, synthesized by the hydrothermal method, where x = 0.0, 0.5, and M present non-magnetic metals (Cu, Al) and magnetic metals (Fe, Ni, Mn) were studied. The crystallite size and porosity of SnO2 were reduced by mixing with Cu, Al, Fe, or Ni, meanwhile, increased by integrating with Mn. The residual stress of SnO2 was increased 5-fold by Mn doping. The energy dispersive X-ray analysis revealed that Al is the lowest ion for full acceptor incorporation into the SnO2 lattice, while the other doped metal ions show better incorporation. SnO2 doping has a significant impact on the particle morphologies of MxSn1−xOy nanocomposites. The Debye temperature (θD) and Young's modulus (Y) were estimated from the FTIR spectra. The value of θD is 633.86 K for SnO2 nanoparticles and increased to 694.68 K for Mn/SnO2, while it decreased to 608.27 K for Fe/SnO2. The value of Y was increased from 518.30 GPa for SnO2 to 864.41 GPa for Cu/SnO2 nanocomposite. The PL intensity of SnO2 was decreased by Cu, Fe, Ni, and Mn doping, whereas it was increased by Al doping. The blueshift was observed for Al/SnO2 and Mn/SnO2, whereas it is a slight ultraviolet shift for Cu/SnO2, Fe/SnO2, and Ni/SnO2 nanocomposites. SnO2 nanoparticle and Al/SnO2 nanocomposite exhibit weak ferromagnetic behavior by increasing the magnetic field (H) up to 4 kG, while with further increase in H, the samples exhibit diamagnetic behavior. In contrast, the Fe/SnO2, Ni/SnO2, and Mn/SnO2 nanocomposites show a paramagnetic trend, while the Cu/SnO2 nanocomposites exhibit a diamagnetic trend in the magnetic field range of 0–20 kG. The saturated magnetization and magnetic moment are enhanced for all MxSn1−xOy nanocomposites, whereas the corrective field and magnetic anisotropy are decreased compared to SnO2 nanoparticles. The findings recommended SnO2 and Al/SnO2 composites for spintronic devices and cathode–luminescence displays, Fe/SnO2, Ni/SnO2, and Mn/SnO2 nanocomposites for magnetic imaging, and Cu/SnO2 composites for catalytic and plastic deformation applications. [ABSTRACT FROM AUTHOR]
- Published
- 2023
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11. Study of bromine substitution on band gap broadening with consequent blue shift in optical properties and efficiency optimization of lead-free CsGeIXBr3−X based perovskite solar cells.
- Author
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Sarkar, Joy, Talukdar, Avijit, Debnath, Pratik, and Chatterjee, Suman
- Abstract
Lead-based perovskite solar cells have experienced tremendous growth and achieved an outstanding power conversion efficiency (PCE) of 27.4% during the last decade. However, lead poisoning has remained a matter of concern for commercialization. Therefore, researchers are looking for alternative perovskite materials free from lead. Cesium-based perovskite material CsGeI
X Br3−X may be a promising alternative due to its favorable optical conductivity and light absorption coefficient. To understand the atomic level calculation of perovskite solar cells (PSCs), a detailed model of interaction between the electrons and the interface is strongly anticipated. The optoelectronic property of the perovskite absorber layer has the most significant impact on device performance. Using Density functional theory (DFT), we can precisely predict the behavior of charge transport layers, including the active perovskite layer. In this work, we have done first-principles calculations based on DFT to analyze the electronic and optical properties of lead-free full inorganic CsGeIX Br3−X perovskite compounds. In addition, we incorporate DFT-extracted values of the electronic band gap, the effective density of states, and the optical absorption spectrum in the Solar cell capacitance simulator (SCAPS-1D) program to understand the device performance with the variation of thickness and total defect density of the perovskite layer. We obtained the value of the energy bandgap as 1.363 eV for CsGeI3 , 1.5795 eV for CsGeI2 Br, 1.7493 eV for CsGeIBr2 and 1.885 eV for CsGeBr3 . The CsGeI3 -based device performs best and achieves maximum power conversion efficiency (PCE) of 27.63%. It was observed that while increasing the doping concentration of Br in CsGeIX Br3−X perovskites, the bond length decreases, and consequently, the bandgap increases. Also, as the doping concentration increases, a substantial blue shift was observed in the calculated optical conductivity and absorption spectra. [ABSTRACT FROM AUTHOR]- Published
- 2023
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12. Black Holes
- Author
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Natário, José and Natário, José
- Published
- 2021
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13. Effects of Ni Doping and Silica Gel Bead Support on Characteristics of TiO2 Catalyst.
- Author
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Nguyen, Nghia Manh, Nguyen, Hue Thi, Negishi, Nobuaki, Nguyen, Khang Cao, Luc, Hoang Huy, and Duong, Van Quoc
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SILICA gel ,TRANSMISSION electron microscopy ,CATALYST supports ,CRYSTAL lattices ,SCANNING electron microscopy - Abstract
Titanium dioxide (TiO
2 ) photocatalyst is an excellent solution that can be utilized to decompose organic pollutants. In this report, Ni-doped TiO2 immobilized on silica gel bead by sol–gel process was investigated. The morphology, crystal phase composition, particle size, porosity characteristics, and optical properties of the samples were investigated through scanning electron microscopy, high-resolution transmission electron microscopy, x-ray diffraction, N2 isothermal loops, Raman spectroscopy, and ultraviolet–visible (UV–Vis) absorption. The results revealed that Ni2+ uniformly distributed in the TiO2 crystal lattice to replace Ti4+ and that Ni2+ did not change the TiO2 anatase crystal phase. Compared with pure TiO2 , the absorption edge of the Ni-doped TiO2 sample exhibited a redshift from 400 nm to 655 nm. Influenced by silica gel bead as catalyst support, the crystal size of Ni-doped TiO2 sample was reduced from 27 nm to 6 nm that led to a blueshift in both Raman and UV–Vis spectra. The photocatalytic enhancement was demonstrated by methyl orange decomposition. Under ultraviolet irradiation, the photocatalytic performance of Ni-doped TiO2 immobilized on silica gel bead was lower compared with pure sample. Opposite to this, Ni-doped TiO2 immobilized on silica gel bead showed photocatalytic enhancement under visible light. [ABSTRACT FROM AUTHOR]- Published
- 2022
- Full Text
- View/download PDF
14. On the stability of a wormhole in the maximally-extended Reissnerâ€"Nordström solution.
- Author
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DeMott, Ross, Major, Sam, and Flournoy, Alex
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SCALAR field theory , *BLACK holes , *SPEED of light , *CENSORSHIP ,UNIVERSE - Abstract
We consider the stability of the maximally-extended Reissnerâ€"Nordström (RN) solution in a Minkowski, de Sitter, or anti-de Sitter background. In a broad class of situations, prior work has shown that spherically symmetric perturbations from a massless scalar field cause the inner horizon of an RN black hole to become singular and collapse. Even if this is the case, it may still be possible for an observer to travel through the inner horizon before it fully collapses, thus violating strong cosmic censorship. In this work, we show that the collapse of the inner horizon and the occurrence of a singularity along the inner horizon are sufficient to prevent an observer from accessing the white hole regions and the parallel Universe regions of the maximally extended RN spaceâ€"time. Thus, if an observer passes through the inner horizon, they will inevitably hit the central singularity. Throughout this article, we use natural units where c = G = 4 π ϵ 0 = 1. [ABSTRACT FROM AUTHOR]
- Published
- 2022
- Full Text
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15. Study of bromine substitution on band gap broadening with consequent blue shift in optical properties and efficiency optimization of lead-free CsGeIXBr3−X based perovskite solar cells
- Author
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Sarkar, Joy, Talukdar, Avijit, Debnath, Pratik, and Chatterjee, Suman
- Published
- 2023
- Full Text
- View/download PDF
16. Monolithic Multi‐Color Tunable Inorganic Light‐Emitting Diodes.
- Author
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Baek, Seung‐Hye, Kim, Hee‐Wung, Lee, Gun‐Woo, and Lee, Sung‐Nam
- Subjects
LIGHT emitting diodes ,PIEZOELECTRICITY ,VISIBLE spectra ,INDIUM gallium nitride ,MONOCHROMATIC light - Abstract
Inorganic light‐emitting diodes (LEDs) possess exceptional advantages for achieving wide wavelength emission ranges. However, certain material limitations should be overcome to alleviate the green gap between InGaN and AlInGaP‐based LEDs. In this study, monolithic red, green, and bluish‐green emissions are achieved by exploiting the blueshift phenomenon, caused by the band‐filling and piezoelectric screening effects. Different‐sized LEDs are designed to control the injection current density on the same wafer. The smaller the size of the LED, the shorter the emission wavelength, resulting in multi‐color emission (from red to bluish‐green). As a result, red, green, and white emissions are individually and simultaneously obtained using dichromatic LED systems, comprising three red and one green LED cell. In addition, a wide range of visible light colors are achieved by adjusting the size of the LEDs and the applies injection current. [ABSTRACT FROM AUTHOR]
- Published
- 2022
- Full Text
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17. Doping content dependencies on the structure modification and bandgap broadening of Al induced sol-gel derived ZnO nanostructures.
- Author
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Marzuki, Marina, Zain, Mohd Zamzuri Mohammad, Ibrahim, Wan Abd Rahman Assyahid Wan, Zainon, Nooraizedfiza, and Ahmad, Rozie Nani
- Subjects
- *
DOPING agents (Chemistry) , *ZINC oxide films , *ZINC oxide , *THIN films , *BAND gaps , *ZINC acetate , *COLLISION broadening - Abstract
This paper reports the Al doping content dependence on structure modification and band gap widening of sol-gel synthesised Al-doped ZnO thin films. The precursor, solvent and stabiliser used to prepare ZnO solution were Zinc Acetate Dihydrate, 2-propanol and ethanolamine, respectively. Molarity fractions of 0, 4, 6 and 8% of Al (NO3)2 as dopant source was incorporated into ZnO host system and prepared by individual buffer solutions. The prepared sols were subsequently deposited onto ITO glass substrates, and the resultant thin films were characterised. XRD patterns exhibit the polycrystalline nature of pure and doped ZnO films, with preferred orientations correspond to (1 0 0), (0 0 2) and (1 0 1) planes. Lattice shrinking is indicated by the decrease lattice constant c due to axial compression. Peaks shifting towards higher angle are observed implying a structural modification over doped thin films that affects the optical properties, which agrees with the lattice shrinking. The absorption edge has an obvious blueshift to the shorter wavelength with increased dopant content. The thin films' energy bands were procured by Tauc's linear extrapolation and was found to be broadening from 3.32 eV to 3.34 eV in 6% Al-doped ZnO. There exists a significant correlation between the applied doping level and the extend of variation of structural properties and ultimately, lattice imperfection. Doping of smaller-atom-sized Al into ZnO concedes with the Burstein-Moss principles. 6% Al doping imposes the highest peak shift and ultimately has the highest impact on lattice parameter and energy band. [ABSTRACT FROM AUTHOR]
- Published
- 2021
18. Progress of 3d metal-doped zinc oxide nanoparticles and the photocatalytic properties
- Author
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Omar Muktaridha, Muhammad Adlim, Suhendrayatna Suhendrayatna, and Ismail Ismail
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Bandgap ,Blueshift ,Dopant ,Nanoparticle ,Redshift ,Chemistry ,QD1-999 - Abstract
Modification of ZnO by doping with 3d metal has been intensively reported, and many interesting applications have been proven. This review elaborated the doping effect of the 3d metal atom (Sc, Ti, V, Cr, Mn, Fe, Co, Ni, and Cu) on the bandgap of ZnO and their application. The review involved more than 190 articles on the 3d metal-doped ZnO, introducing some fundamental theories, including doping types, nanoparticle synthesis methods, nanoparticle morphologies, and lattice size changes. The preparation methods of 3d metal-doped ZnO and the particle morphology effect are elaborated before discussing the correlation between dopant characteristics (type, content, radii) and the bandgap and crystallite size properties. The review ended with the application and photocatalytic degradation for dye in the visible and ultraviolet irradiation.
- Published
- 2021
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19. Effects of Ni Doping and Silica Gel Bead Support on Characteristics of TiO2 Catalyst
- Author
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Nguyen, Nghia Manh, Nguyen, Hue Thi, Negishi, Nobuaki, Nguyen, Khang Cao, Luc, Hoang Huy, and Duong, Van Quoc
- Published
- 2022
- Full Text
- View/download PDF
20. Influence of Sn2+ ion on structural, morphological and optical characteristics of Cd0.9−xZn0.1SnxS (0 ≤ x ≤ 0.06) quantum dots.
- Author
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Devadoss, I., Sakthivel, P., and Pauline Sheeba, S.
- Abstract
Water-soluble Cd
0.9−x Zn0.1 Snx S (0 ≤ x ≤ 0.06) quantum dots were prepared by dual doping of Sn and Zn via chemical co-precipitation technique. XRD results confirmed the cubic structure of CdS crystallites without generating any secondary peaks due to doping. TEM analysis revealed the structural information of the Sn-doped CdS host. The Sn substitution enhanced the particle size lightly. The surface morphological study revealed that the agglomeration of the samples was decreased. From UV–visible optical study, it was observed that the optical transmittance was suppressed owing to Sn substitution. Absorption peaks were blueshifted, and band gap values were widened due to incorporation of Sn. The strong PL emission peaks were received at 400 nm−1 and weak peaks near 490 nm−1 . The peaks originated near the UV region were due to sulfur vacancies on the surface. EDX and FTIR studies confirmed the presence of Sn in the prepared samples. Since the possibility of tailoring the band gap toward a high energy gap, these materials composition may be selected for optoelectronic device fabrication. [ABSTRACT FROM AUTHOR]- Published
- 2021
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21. Biogenic ZnO nanoparticles: a study of blueshift of optical band gap and photocatalytic degradation of reactive yellow 186 dye under direct sunlight
- Author
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Singh Jagpreet, Kaur Sukhmeen, Kaur Gaganpreet, Basu Soumen, and Rawat Mohit
- Subjects
blueshift ,coriandrum sativum ,green synthesis ,optical band gap ,photodegradation ,reactive yellow 186 ,zno nps ,Chemistry ,QD1-999 - Abstract
Synthesis of nanoparticles (NPs) using plant extracts has been suggested as an environmentally friendly alternative to chemical synthesis of semiconductor NPs. In the present study, ZnO NPs were synthesized by a simple and cost-effective method using Coriandrum sativum leaf extract and zinc acetate as precursors. The as-synthesized ZnO NPs were characterized by UV-visible spectroscopy, transmission electron microscopy (TEM), Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM) and energy dispersive X-ray (EDX) analysis. The results confirmed the formation of ZnO NPs with a wurtzite structure, spherical shape and average particle size of 24 nm. The photocatalytic degradation of reactive yellow 186 (RY 186) dye was carried out under direct sunlight irradiation and its degradation efficiency and apparent rate constant (K’app) of reaction were calculated to be 93.38%, and 0.0019 min−1, respectively. The optical band gap value of the as-synthesized ZnO NPs was found to be 3.4 eV, which indicates the presence of blueshift. Owing to the presence of blueshift and a wide band gap of synthesized biogenic ZnO NPs, the overall absorption of sunlight irradiation will be enhanced, which leads to higher degradation efficiency of the dye. The current study thus highlights the optical band gap properties of biogenic ZnO NPs and their significance as a heterogeneous catalyst for the purification of polluted water.
- Published
- 2019
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22. Indium Localization‐Induced Red, Green, and Blue Emissions of Semipolar (11‐22) GaN‐Based Light‐Emitting Diodes.
- Author
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Choi, Jun-Ho, Baek, Seung-Hye, Kim, Hee-Wung, Na, Hyunseok, and Lee, Sung-Nam
- Subjects
- *
LIGHT emitting diodes , *INDIUM , *ELECTROLUMINESCENCE , *SURFACE structure , *RED , *SURFACE area , *INDIUM gallium nitride , *GALLIUM nitride - Abstract
Red, green, and blue electroluminescence (EL) in semipolar (11‐22) GaN‐based light‐emitting diodes (LEDs) is achieved using SiO2 hexagonal patterns epitaxial lateral overgrowth (HP‐ELO). The size, density, and area of arrowhead‐like surface structure of the semipolar (11‐22) HP‐ELO GaN are significantly affected by increasing the SiO2 hexagonal patterns from 6.0 to 15.0 μm. The full width at half maximum and the blueshift wavelength of EL spectra increases with increasing from 6.0 to 9.0 μm, and then decreases with increasing the hexagonal pattern width to 15.0 μm. These results show a similar tendency to the surface area of arrowhead‐like structure. In addition, micro‐EL images show that indium localization‐induced low energy emission initiates at the front end of arrowhead‐like pattern, and then blueshifted emissions propagate to the side edges as the injection current increases. Therefore, it suggests that HP‐ELO can control the arrowhead‐like surface structure composed of different indium compositions, which can achieve red, green, and blue emissions of a semipolar (11‐22) HP‐ELO GaN‐based LED. [ABSTRACT FROM AUTHOR]
- Published
- 2020
- Full Text
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23. Law of physics 20th-century scientists overlooked. II. Energy generation via velocity differential blueshift.
- Author
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Ranzan, Conrad
- Abstract
Theorists of the 20th century had failed to recognize an underlying law of physics governing the propagation of light: linearly propagating electromagnetic radiation (and neutrinos) is subject to the Principle of velocity differential propagation. The Principle, which is shown to rest on sound physics, has two manifestations: the second of these, the blueshifting of light (and neutrinos) within the internal portion of a gravity well, is explored. The Principle is applied to an end-state neutron star (a stable gravitationally collapsed body). Examined is its energy layer, the energy generation/amplification that takes place there, and the mechanism by which the energy escapes to the external world. Highlighted is the steady-state perpetual nature of the process; and its applicability in solving two of the most intractable problems in astrophysics. The implications for cosmology are profound and incontrovertible. [ABSTRACT FROM AUTHOR]
- Published
- 2020
- Full Text
- View/download PDF
24. Strong Band Gap Blueshift in Copper (I) Oxide Semiconductor via Bioinspired Route.
- Author
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Polishchuk, Iryna, Bianco‐Stein, Nuphar, Lang, Arad, Kurashvili, Mariam, Caspary Toroker, Maytal, Katsman, Alexander, Feldmann, Jochen, and Pokroy, Boaz
- Subjects
- *
SEMICONDUCTORS , *QUANTUM confinement effects , *CRYSTAL lattices , *UNIT cell , *COPPER crystals - Abstract
Semiconductors have numerous applications in both science and technology. Several methods have been developed to engineer their band gap, which is one of the most important parameters of semiconductors. Here, it is shown that the incorporation of various amino acids into the crystal lattice of copper (I) oxide, akin to the way living organisms incorporate organic macromolecules into minerals during biomineralization, leads to significant shrinkage in the volume of the host unit cell and a strong blueshift in the band gap of up to ≈18%. In examining the potential location of the bio‐organic molecules within the inorganic host's lattice, a very good fit between the proposed model of incorporation and experimental findings is found. The bioinspired phenomenon of band gap widening is thought to be attributable to the void‐induced quantum confinement effect, even though observed in micrometer‐sized crystals. This hypothesis is supported by developing a tight‐binding model that is found to fit well with the experimental data. The outcome of this research could profoundly impact the fields of light‐emitting and spin‐based devices as well as opens up a new bioinspired route to tune the band gap of semiconductors. [ABSTRACT FROM AUTHOR]
- Published
- 2020
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25. Photoluminescence emissions of Ca1−WO4:xEu3+: Bridging between experiment and DFT calculations
- Author
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Marcelo Assis, Aline Estefany Brandão Lima, Eduardo O. Gomes, Juan Andrés, Elson Longo, Daniele de Souza, Eva Guillamón, Yara Gobato Galvão, Amanda F. Gouveia, Miguel A. San-Miguel, Lara Kelly Ribeiro, Ieda Lúcia Viana Rosa, and Geraldo E. Luz
- Subjects
rare earths ,Range (particle radiation) ,Potential well ,Photoluminescence ,Materials science ,Band gap ,Doping ,Analytical chemistry ,General Chemistry ,DFT calculations ,xEu3+ [Ca1−xWO4] ,Blueshift ,Absorption edge ,Geochemistry and Petrology ,photoluminescence emissions ,Density functional theory - Abstract
In this work, the impact of the doping process on the photoluminescence emission of CaWO4 as a function of the concentration of Eu3+ cation (0.01 mol%, 0.02 mol%, 0.04 mol%, 0.06 mol%, 0.08 mol%, and 0.10 mol%) is discussed in detail. Ca1−xWO4:xEu3+ samples were successfully synthesized by a simple co-precipitation method followed by microwave irradiation. The blue shift in the absorption edge confirmed the quantum confinement effect and the band gap energy cover the range from 3.91 to 4.18 eV, as the amount of Eu3+ cations increases. The experimental results are sustained by first-principles calculations, at the density functional theory level, to decipher the geometry and electronic properties, thereby enabling a more accurate and direct comparison between theory and experiment for the Ca1−xWO4:xEu3+ structure. Funding for open access charge: CRUE-Universitat Jaume I
- Published
- 2022
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26. GEON particle, the missing link between Quantum Physics and General Relativity
- Author
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Wim Vegt
- Subjects
General Relativity ,GEONs ,Quantum Field Theory ,Gravitational-Electromagnetic Interaction ,Quantum Physics ,Gravitational RedShift ,RedShift ,BlueShift ,Galaxies ,Elementary Particles - Abstract
The article presents a new theory in physics which explains the interaction between gravity and light with mathematical results close to General Relativity (15 digits beyond the decimal point equal result) and unifies General Relativity with Quantum Physics by the fundamental elementary particle: the GEON. The GEON [1] is a fundamental solution of the relativistic quantum mechanical Dirac equation (Quantum Physics) and the confinement has been controlled by the fundamental interaction between Gravity and Light (General Relativity). The GEON is the most fundamental elementary particle and can be created by the compression of light into extremely high densities. The GEON appears when an equilibrium has been established between the expanding radiation pressure of light and the confining gravitational force of light. The GEON is the fundamental solution of the relativistic quantum mechanical Dirac equation. For this reason the GEON particle unifies Quantum Physics with General Relativity. The confinement of GEONS is only possible at discrete values. (Quantisation of Energy, Light and Gravity). The GEON carries the mass inside the structures of matter (Elementary Particles). The radius of a GEON with the mass of a proton (1.67×10-27 kg) equals 3 10-58 [m]. [30] PlotGraph 3, page 24 The new theory in physics has been based on the “divergence-free linear 4-dimensional stress-energy tensor in the Minkowski Space”. The difference between Einstein’s General Relativity and this theory is the different approach. Einstein has deformed (non-linear and non-divergence free) the “4-dimensional Stress-Energy Tensor” by introducing the curved 4-dimensional Riemannian Manifold to explain the interaction between Gravity and Light. The new theory describes the interaction between different fields (Electric, Magnetic and Gravitational) by identical interaction terms, generated by the separate divergence and the separate rotation of the different fields. (equation 24) The conclusion of the new theory is that “divergence-free” and “rotation-free” fields do not interact. When Isaac Newton published his 3 famous equations which became the foundation of Classical Dynamics, he was not aware that he was building the first elemental blocks for the Stress-Energy Tensor in the 4-dimensional Minkowski Space. When James Clerk Maxwell published his 4 famous equations which became the foundation for Classical Electrodynamics, he was not aware that he was building new blocks for the Stress-Energy Tensor in the 4-dimensional Minkowski Space. When Paul Dirac published his famous equation which became the foundation of Relativistic Quantum Physics, he was not aware that he was building further on blocks for the Stress-Energy Tensor in the 4-dimensional Minkowski Space. It was Albert Einstein who was one of the first physicists who discovered the importance of the Stress-Energy Tensor to describe in a mathematical way the interaction between Electromagnetic Radiation and a Gravitational Field. Because there was no match, Einstein deformed the Divergence-Free Linear “Stress-Energy Tensor” by deforming Space and Time. Using curved Riemannian manifolds, he deformed the fundamental Tensor in physics in such a way that he found a very special Mathematics to describe the interaction between Electromagnetic Radiation (Light) and a Gravitational Field. The Theory of General Relativity. This became a fundamental problem in physics. By deforming the fundamental building block in physics (the Divergence-Free Linear “Stress-Energy Tensor), there is no match anymore in the fundamental mainstreams in physics (classical mechanics, electrodynamics, quantum physics and general relativity). Classical Mechanics has no match with Classical Electrodynamics. Classical Electrodynamics has no match with Relativistic Quantum Physics. Relativistic Quantum Physics has no match with General Relativity. It is important to distinguish the “Physical Reality” from a Mathematical Description of it (which is in general an approach). The scalar curvature (or the Ricci scalar) is a measure of the curvature of a Riemannian manifold. Einstein used a curved Riemannian manifold to describe “Gravitational-Electromagnetic Interaction”. But the physics beyond this is the interaction between the different fields. It is possible to describe this in different ways. This new theory demonstrates a more direct approach in the force densities acting between different fields expressed by equation (24). This new theory starts with the Divergence-Free Linear “Stress-Energy Tensor” in the 4-dimensional Minkowski Space. And from this unique Divergence-Free “Stress-Energy Tensor” follows Classical Mechanics, Classical Electrodynamics, Relativistic Quantum Physics and General Relativity. Bringing back the necessary unity in physics. Theories which unify Quantum Physics and General Relativity, like “String Theory”, predict the non-constancy of natural constants. Accurate observations of the NASA Messenger [11] observe in time a value for the gravitational constant “G” which constrains until ( /G to be < 4 × 10-14 per year) . One of the characteristics of the New Theory is the “Constant Value” in time for the Gravitational Constant “G”. A second experiment to test the New Theory is the effect of “Gravitational RedShift” [2]. The “Gravitational RedShift” between an observatory on Earth (Radius = 6 106 [m]) and a Satellite in a Galileo Orbit (Radius = 23222 103 [m]) according “General Relativity”: The “Gravitational RedShift” between an observatory on Earth (Radius = 6 106 [m]) and a Satellite in a Galileo Orbit (Radius = 23222 103 [m]) according “The Proposed Theory”:  
- Published
- 2023
27. Strategies of motion under the black hole horizon.
- Author
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Toporensky, A. V. and Zaslavskii, O. B.
- Subjects
- *
GENERAL relativity (Physics) , *SCHWARZSCHILD metric , *BLACK holes , *SCHWARZSCHILD black holes , *HORIZON , *MOTION - Abstract
In this methodological paper, we consider two problems an astronaut faces under the black hole horizon in the Schwarzschild metric. (1) How to maximize the survival proper time. (2) How to make a visible part of the outer universe as large as possible before hitting the singularity. Our consideration essentially uses the concept of peculiar velocities based on the "river model." Let an astronaut cross the horizon from the outside. We reproduce from the first principles the known result that point (1) requires that an astronaut turn off the engine near the horizon and follow the path with the momentum equal to zero. We also show that point (2) requires maximizing the peculiar velocity of the observer. Both goals (1) and (2) require, in general, different strategies inconsistent with each other that coincide at the horizon only. The concept of peculiar velocities introduced in a direct analogy with cosmology and its application for the problems studied in this paper can be used in advanced general relativity courses. [ABSTRACT FROM AUTHOR]
- Published
- 2020
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28. Synthesis, characterization and optical studies on Sm2+-doped CdSe nanocrystals: a blueshift and fixed emission with high quantum yields.
- Author
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Yang, Jun-Hong, Gao, Jun-Fang, Yong, Sheng-Li, Ma, Xue-Lin, and Liu, Li-Jing
- Abstract
CdSe:Sm nanocrystals (NCs) were synthesized by a water phase method, and their structures, shapes and optical properties were further characterized. X-ray diffraction (XRD) analysis suggested that both the CdSe and CdSe:Sm NCs contained (111), (220) and (311) lattice planes in the zinc blende structure overlapped with the (002), (110) and (112) lattice planes in the wurtzite structure, and the diameters were about 4.2, 3.3 and 2.3 nm for CdSe, CdSe:Sm(8%) and CdSe:Sm(10%) NCs, respectively. All of the CdSe:Sm NCs were monodispersed and uniform spherical nanocrystals. The CdSe:Sm(10%) NCs prepared with different reaction times exhibited constant absorption spectra at 430 nm and a fixed emission peak at 581 nm. Compared with those of pure CdSe NCs, the fluorescence emission of CdSe:Sm(10%) NCs blueshifted 20–36 nm, and the absorption peak initially redshifted and then blueshifted with the prolongation of reaction time. In addition, the Sm
2+ doping decreased the fluorescence lifetime and increased the quantum yields (QYs) of CdSe NCs. The QYs of CdSe:Sm NCs increased initially and then decreased with the increase in the amount of doped Sm2+ . The initial pH and charge compensator concentration also exhibited significantly enhanced fluorescence emission of CdSe:Sm NCs. CdSe and CdSe:Sm NCs were prepared via a water phase method. The structure and optical properties were investigated; the Sm2+ was doped into CdSe NCs successfully. CdSe and CdSe:Sm NCs all exhibit nearly spherical particles, doping Sm2+ increases the particle size, and the QYs are also enhanced. As the reaction time varies to 1, 2, 5, 8 and 10 h, the emission spectra of CdSe NCs present redshift, while the CdSe:Sm NCs have a fixed emission peak, which is the characteristic peak of Sm2+ . As compared with pure CdSe NCs, the emission spectra of CdSe:Sm NCs appear blueshift by 20–36 nm. Doping Sm2+ into CdSe NCs can improve the optical properties. [ABSTRACT FROM AUTHOR]- Published
- 2019
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29. Electromagnetic radiation and inertial forces.
- Author
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Elektronov, Nasko and Kushev, Zhivko
- Subjects
- *
DOPPLER effect , *CORIOLIS force , *ELECTROMAGNETIC waves , *ELECTROMAGNETIC radiation , *PHOTONS - Abstract
The influence of the Coriolis inertial force generated by the orbital and spin motions of distant objects on the electromagnetic radiation energies during the exchange of photons between such objects has been considered. A red or blue spectral shift occurrence in a passive observation mode that is not associated with the Doppler effect or other known effects has also been shown. The relations found are used to calculate the spectral shifts for several nearby stars from our galaxy, as well as the spectral shifts of several galaxies. The results are close to the values currently observed. [ABSTRACT FROM AUTHOR]
- Published
- 2019
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30. Type I organic quantum wells made of two organic semiconductors.
- Author
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Gao, Chenxu, Zhu, Yueyue, Li, Congling, and Lv, Aifeng
- Subjects
- *
ORGANIC semiconductors , *QUANTUM wells , *LIGHT absorption , *HETEROJUNCTIONS - Abstract
[Display omitted] • Type I organic quantum wells (OQWs) were fabricated in physical sense. • Blueshifts in the optical absorptions of the OQWs were observed. • Negative differential resistance (NDR) behaviors were obtained. Construction of organic quantum wells (OQWs) has been a challenge due to the difficulty in fabricating high-quality organic films in large area. Here, type I OQWs are successfully fabricated by using two OSCs with different bandgaps, and they exhibit both negative differential resistance (NDR) effect and absorption blueshift. Moreover, the OQW photoswitches show much higher photoresponsivity than the corresponding organic heterojunction ones. All the above results prove the successful construction of OQWs in a physical sense. [ABSTRACT FROM AUTHOR]
- Published
- 2023
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31. Detection of Acetamiprid by Aptamer Based on a Porous Silicon Microcavity
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Xiaohui Huang, Zhenhong Jia, Yun Gao, Xiaoyi Lv, and Lanlan Bai
- Subjects
Materials science ,acetamiprid ,Aptamer ,Physics::Optics ,Porous silicon ,Acetamiprid ,law.invention ,chemistry.chemical_compound ,Etching (microfabrication) ,law ,Applied optics. Photonics ,Electrical and Electronic Engineering ,Quantitative Biology::Biomolecules ,graphene quantum dots ,business.industry ,Graphene ,aptamer ,QC350-467 ,Optics. Light ,Atomic and Molecular Physics, and Optics ,TA1501-1820 ,Blueshift ,Quantitative Biology::Quantitative Methods ,chemistry ,Quantum dot ,Optoelectronics ,business ,Refractive index - Abstract
In this paper, a new method for pesticide detection based on porous silicon microcavities was proposed. First, the aptamer of acetamiprid was fixed in the functionalized porous silicon microcavity. Then, the complementary strand of the aptamer modified with graphene quantum dots was hybridized with the aptamer, and the effective refractive index of the porous silicon microcavity increased. When acetamiprid was added, it bound to the aptamer due to its stronger specificity. The aptamer separated from the complementary strand of the coupled graphene quantum dots and bound to acetamiprid, resulting in a decrease in the effective refractive index, and its central wavelength of reflection spectrum was blue shifted, and the blueshift increased with the increase of acetamiprid concentration. The relationship between the change in central wavelength and the concentration of acetamiprid was analysed, and the detection limit of acetamiprid was 151 nm.
- Published
- 2022
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32. Glucosylceramide acyl chain length is sensed by the glycolipid transfer protein.
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Backman, Anders P. E., Halin, Josefin, Nurmi, Henrik, Möuts, Anna, Kjellberg, Matti A., and Mattjus, Peter
- Subjects
- *
GLUCOSYLCERAMIDES , *GLYCOLIPIDS , *ENDOPLASMIC reticulum , *SURFACE plasmon resonance , *LIPID transfer protein - Abstract
The glycolipid transfer protein, GLTP, can be found in the cytoplasm, and it has a FFAT-like motif (two phenylalanines in an acidic tract) that targets it to the endoplasmic reticulum (ER). We have previously shown that GLTP can bind to a transmembrane ER protein, vesicle-associated membrane protein-associated protein A (VAP-A), which is involved in a wide range of ER functions. We have addressed the mechanisms that might regulate the association between GLTP and the VAP proteins by studying the capacity of GLTP to recognize different N-linked acyl chain species of glucosylceramide. We used surface plasmon resonance and a lipid transfer competition assay to show that GLTP prefers shorter N-linked fully saturated acyl chain glucosylceramides, such as C8, C12, and C16, whereas long C18, C20, and C24-glucosylceramides are all bound more weakly and transported more slowly than their shorter counterparts. Changes in the intrinsic GLTP tryptophan fluorescence blueshifts, also indicate a break-point between C16- and C18-glucosylceramide in the GLTP sensing ability. It has long been postulated that GLTP would be a sensor in the sphingolipid synthesis machinery, but how this mechanistically occurs has not been addressed before. It is unclear what proteins the GLTP VAP association would influence. Here we found that if GLTP has a bound GlcCer the association with VAP-A is weaker. We have also used a formula for identifying putative FFAT-domains, and we identified several potential VAP-interactors within the ceramide and sphingolipid synthesis pathways that could be candidates for regulation by GLTP. [ABSTRACT FROM AUTHOR]
- Published
- 2018
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33. Synthesis, luminescence, and excited‐state absorption properties of disubstituted perylene diimide derivatives modified at bay region
- Author
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Qing Zhang, Hongjun Zhu, Qian Cheng, Senqiang Zhu, Zhiyuan Chen, and Rui Liu
- Subjects
Luminescence ,Materials science ,Chemical Phenomena ,Biophysics ,Quantum yield ,Electrons ,Photochemistry ,Blueshift ,chemistry.chemical_compound ,chemistry ,Chemistry (miscellaneous) ,Diimide ,Ultrafast laser spectroscopy ,Density functional theory ,Absorption (electromagnetic radiation) ,Perylene - Abstract
Three A-π-A or D-π-D perylene diimide (PDI) derivatives with varied groups on π-conjugate were synthesized and characterized. The photophysical properties of these compounds were systematically studied by spectral experiments and density functional theory calculations. All compounds displayed intense absorption bands at 300-800 nm wavelengths. However, diverse groups on the π-conjugate influenced the UV-vis absorption. Electron-withdrawing groups on PDI-2 caused a slight red shift at the 350-400 nm wavelength and a blue shift after 400 nm wavelength. At the same time, the electron-donating substituents on PDI-3 caused an obvious red shift of this band. These PDI derivatives exhibited emission in solution at room temperature (λem = 500-850 nm). The quantum yield of PDI-3 decreased, while the electron-donating substituents were introduced to the π-conjugated motifs. However, the quantum yield of PDI-2 increased when electron-withdrawing substituents were introduced to the π-conjugated motifs. In addition, PDI-1 and PDI-2 exhibited broad triplet transient absorption in the visible region. These photophysical properties could help us to understand the relationship between structure and photophysical properties of perylene diimide derivatives and exploit more original perylene diimide-based optical functional materials.
- Published
- 2021
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34. Theoretical Aspects of Nonconventional Hydrogen Bonds in the Complexes of Aldehydes and Hydrogen Chalcogenides
- Author
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Minh Tho Nguyen, Vu Thi Ngan, Nguyen Thi Thanh Cuc, Cam-Tu D. Phan, Nguyen Tien Trung, and Nguyen Thi Ai Nhung
- Subjects
Red shift ,Crystallography ,Hydrogen ,Chemistry ,Hydrogen bond ,Ab initio quantum chemistry methods ,Halogen ,Molecule ,chemistry.chemical_element ,Physical and Theoretical Chemistry ,Ternary operation ,Blueshift - Abstract
Hydrogen bonds (H-bonds) in the complexes between aldehydes and hydrogen chalcogenides, XCHO...nH2Z with X = H, F, Cl, Br, and CH3, Z = O, S, Se, and Te, and n = 1,2, were investigated using high-level ab initio calculations. The Csp2-H...O H-bonds are found to be about twice as strong as the Csp2-H...S/Se/Te counterparts. Remarkably, the S/Se/Te-H...S/Se/Te H-bonds are 4.5 times as weak as the O-H...O ones. The addition of the second H2Z molecule into binary systems induces stronger complexes and causes a positive cooperative effect in ternary complexes. The blue shift of Csp2-H stretching frequency involving the Csp2-H...Z H-bond sharply increases when replacing one H atom in HCHO by a CH3 group. In contrast, when one H atom in HCHO is substituted with a halogen, the magnitude of blue-shifting of the Csp2-H...Z H-bond becomes smaller. The largest blue shift up to 92 cm-1 of Csp2-H stretching frequency in Csp2-H...O H-bond in CH3CHO...2H2O has rarely been observed and is much greater than that in the cases of the Csp2-H...S/Se/Te ones. The Csp2-H blue shift of Csp2-H...Z bonds in the halogenated aldehydes is converted into a red shift when H2O is replaced by a heavier analogue, such as H2S, H2Se, or H2Te. The stability and classification of nonconventional H-bonds including Csp2-H...Se/Te, Te-H...Te, and Se/Te-H...O have been established for the first time.
- Published
- 2021
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- View/download PDF
35. Tuning the crystal structure and optical properties of selective area grown InGaAs nanowires
- Author
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Zahra Azimi, Chennupati Jagadish, Jennifer Wong-Leung, Li Li, Hark Hoe Tan, Aswani Gopakumar, Hieu T. Nguyen, Thien N. Truong, and A. S. Ameruddin
- Subjects
Photoluminescence ,Materials science ,business.industry ,Nanowire ,Substrate (electronics) ,Condensed Matter Physics ,Epitaxy ,Microstructure ,Atomic and Molecular Physics, and Optics ,Blueshift ,Selective area epitaxy ,Optoelectronics ,General Materials Science ,Electrical and Electronic Engineering ,business ,Wurtzite crystal structure - Abstract
Catalyst-free InGaAs nanowires grown by selective area epitaxy are promising building blocks for future optoelectronic devices in the infrared spectral region. Despite progress, the role of pattern geometry and growth parameters on the composition, microstructure, and optical properties of InGaAs nanowires is still unresolved. Here, we present an optimised growth parameter window to achieve highly uniform In1−xGaxAs nanowire arrays on GaAs (111)B substrate over an extensive range of Ga concentrations, from 0.1 to 0.91, by selective-area metal-organic vapor-phase epitaxy. We observe that the Ga content always increases with decreasing In/(Ga+In) precursor ratio and group V flow rate and increasing growth temperature. The increase in Ga content is supported by a blue shift in the photoluminescence peak emission. The geometry of the nanowire arrays also plays an important role in the resulting composition. Notably, increasing the nanowire pitch size from 0.6 to 2 µm in a patterned array shifts the photoluminescence peak emission by up to 120 meV. Irrespective of these growth and geometry parameters, the Ga content determines the crystal structure, resulting in a predominantly wurtzite structure for xGa ≤ 0.3 and a predominantly zinc blende phase for xGa ≥ 0.65. These insights on the factors controlling the composition of InGaAs nanowires grown by a scalable catalyst-free approach provide directions for engineering nanowires as functional components of future optoelectronic devices.
- Published
- 2021
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- View/download PDF
36. Density Functional Theory Analysis of Structural, Electronic, and Optical Properties of Mixed-Halide Orthorhombic Inorganic Perovskites
- Author
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Hamid M. Ghaithan, Zeyad A. Alahmed, Saif M. H. Qaid, and Abdullah S. Aldwayyan
- Subjects
Materials science ,Band gap ,General Chemical Engineering ,Analytical chemistry ,Halide ,General Chemistry ,Spin–orbit interaction ,Article ,Blueshift ,WIEN2k ,Chemistry ,Density functional theory ,Orthorhombic crystal system ,Absorption (electromagnetic radiation) ,QD1-999 - Abstract
Inorganic metal-halide perovskites hold a lot of promise for solar cells, light-emitting diodes, and lasers. A thorough investigation of their optoelectronic properties is ongoing. In this study, the accurate modified Becke Johnson generalized gradient approximation (mBJ-GGA) method without/with spin orbital coupling (SOC) implemented in the WIEN2k code was used to investigate the effect of mixed I/Br and Br/Cl on the electronic and optical properties of orthorhombic CsPb(I1-x Br x )3 and CsPb(Br1-x Cl x )3 perovskites, while the Perdew-Burke-Ernzerhof generalized gradient approximation (PBE-GGA) method was used to investigate their structural properties. The calculated band gap (Eg) using the mBJ-GGA method was in good agreement with the experimental values reported, and it increased clearly from 1.983 eV for CsPbI3 to 2.420 and 3.325 eV for CsPbBr3 and CsPbCl3, respectively. The corrected mBJ + SOC Eg value is 1.850 eV for CsPbI3, which increased to 2.480 and 3.130 eV for CsPbBr3 and CsPbCl3, respectively. The calculated photoabsorption coefficients show a blue shift in absorption, indicating that these perovskites are suitable for optical and optoelectronic devices.
- Published
- 2021
37. Emission tuning of highly efficient quaternary Ag-Cu-Ga-Se/ZnSe quantum dots for white light-emitting diodes
- Author
-
Yi Qiu, Zhe Hu, Siyu Liu, Wanlu Zhang, Hanqing Dai, Wenjie Zhou, Ruiqian Guo, Zhongjie Cui, Haiyang He, Fengxian Xie, Yuanyuan Chen, and Jinxin Wei
- Subjects
Materials science ,Photoluminescence ,business.industry ,Lattice distortion ,Quantum yield ,02 engineering and technology ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,0104 chemical sciences ,Surfaces, Coatings and Films ,Electronic, Optical and Magnetic Materials ,Blueshift ,Nanomaterials ,Biomaterials ,Colloid and Surface Chemistry ,Quantum dot ,White light ,Optoelectronics ,0210 nano-technology ,business ,Diode - Abstract
With the blooming development of zero-dimensional nanomaterials, I-III-VI alloying quantum dots (QDs) with outstanding photoelectrical properties have emerged to attract much attention as promising environmentally-friendly substitutions for conventional binary Cd-based QDs. In this work, a facile one-pot method was introduced to synthesize unreported quaternary Ag-Cu-Ga-Se/ZnSe (ACGSe/ZnSe) QDs. A relatively high photoluminescence quantum yield (PL QY) of 71.9% and a tunable emission from 510 to 620 nm were successfully achieved. We explored the roles of alloying compositions in ACGSe/ZnSe QDs, inferring that increased Ag proportion would not only lower the Vdefect level which leads to the blue shift of emission, but also slow the ZnSe shelling process owing to the larger lattice distortion. At last, the white light-emitting diodes (WLEDs) were fabricated with ACGSe/ZnSe QDs as the conversion layer, indicating that the as-prepared QDs are a promising candidate for further applications.
- Published
- 2021
- Full Text
- View/download PDF
38. Yb2+-Alloyed Cs4PbI6–CsPbI3 Perovskite Nanocomposites for Efficient and Stable Pure-Red Emission
- Author
-
Zhangben Dai, Junsheng Chen, and Bin Yang
- Subjects
Materials science ,Photoluminescence ,Nanocomposite ,Chemical engineering ,Nanocrystal ,General Materials Science ,Thermal stability ,Physical and Theoretical Chemistry ,Spectral line ,Auger ,Perovskite (structure) ,Blueshift - Abstract
A series of Yb2+-alloyed CsPb1-xYbxI3 (x = 0, 0.2, 0.4, 0.6) perovskite nanocrystals (NCs): are synthesized by a modified hot-injection method. Yb2+ alloying induced a blue shift of photoluminescence (PL) spectra. In particular, when x = 0.6, the perovskite NCs exhibit pure-red emission with PL centered at 638 nm. Furthermore, the perovskite NCs with pure-red emission exhibit enhanced air and thermal stability, compared to pure CsPbI3 NCs. The enhanced stability can be assigned to the formation Cs4PbI6-CsPbI3:Yb composites. Charge-carrier dynamics study indicates that the Cs4PbI6-CsPbI3:Yb composites exhibit ultrafast hot-carrier cooling processes, which could break the Auger reheating effect. These properties suggest the Yb2+ alloyed CsPbI3 perovskite NCs have great potential for high-performance pure-red light-emitting diodes.
- Published
- 2021
- Full Text
- View/download PDF
39. Probing defects and their implications in pH-controlled ZnO QDs: a theory-aided experimental investigation
- Author
-
Somaditya Sen, Mukul Kumar, Deepali Sinha, Sudip Chakraborty, Ashish Gaurav, Prashant Kumar Mishra, and Jagjit Kaur
- Subjects
Photoluminescence ,Materials science ,Band gap ,Condensed Matter Physics ,Atomic and Molecular Physics, and Optics ,Electron localization function ,Electronic, Optical and Magnetic Materials ,Blueshift ,Chemical engineering ,Electrical resistance and conductance ,Density functional theory ,Crystallite ,Electrical and Electronic Engineering ,Visible spectrum - Abstract
ZnO QDs at different pH (8–12) concentrations were prepared using the hydrothermal method. The crystallite size decreases with the increase of pH concentration in the range of ~ 8 nm to ~ 4 nm. FESEM studies confirm the agglomerated highly dense homogeneous QDs. Optical studies reveal decrement in optical band gap with highly confined QDs. The detailed study of photoluminescence of ZnO QDs signifies the presence of the defect between the conduction band and the valence band. Drastic blue shift and enhancement in oxygen vacancies are obtained with more confined QDs as pH increases. The electrical conductance improves considerably and may be due to the increase in oxygen-related defects with increasing pH. With increasing pH the UV sensitivity increases but for all visible light decreases. Using density functional theory structural, electronic and electron localization functions have been determined. Hence a co-related study of experimental and theoretical work of prepared QDs is investigated.
- Published
- 2021
- Full Text
- View/download PDF
40. Electronic and Vibrational Decoupling in Chemically Exfoliated Bilayer Thin Two-Dimensional V2O5
- Author
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Reshma P R, Ganesan Karuppiah, Sandip Dhara, Anees Pazhedath, Arun K. Prasad, Arup Dasgupta, and Shyam Kanta Sinha
- Subjects
Materials science ,Band gap ,Phonon ,Bilayer ,Blueshift ,symbols.namesake ,Transition metal ,Chemical physics ,Molecular vibration ,symbols ,General Materials Science ,Physical and Theoretical Chemistry ,Raman spectroscopy ,Decoupling (electronics) - Abstract
The synthesis of high-quality two-dimensional (2D) transition metal oxides is challenging compared to 2D transition metal dichalcogenides as a result of the exotic surface changes that can appear during formation. Herein, we report the synthesis of bilayer 2D V2O5 nanosheets with a thickness of ∼1 nm using the chemical exfoliation method and a comprehensive study on the vibrational and optical properties of bilayer 2D V2O5. We report, for the first time, a thickness-dependent blue shift of 1.33 eV in the optical bandgap, which signifies the emergence of electronic decoupling in bilayer 2D V2O5. In addition, a thickness-dependent vibrational decoupling of phonon modes observed via Raman spectroscopy fingerprinting was verified by computing the lattice vibrational modes using the density functional perturbation theory. We demonstrate that the manifestation of the electronic and vibrational decoupling can be used as a benchmark to confirm the successful formation of bilayer 2D V2O5 from its bulk counterpart.
- Published
- 2021
- Full Text
- View/download PDF
41. Spin-polarized room temperature ferromagnetism in co-doped ZnO synthesized by electrodeposition
- Author
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Seema Sharma, Rakesh Kumar Singh, Deepika, Ritesh Kumar, Pratyush Vaibhav, Santosh Kumar, Rajnish Kumar Singh, Raju Kumar, and Nishant Kumar
- Subjects
Materials science ,X-ray photoelectron spectroscopy ,Ferromagnetism ,Infrared ,Analytical chemistry ,General Physics and Astronomy ,Crystallite ,Crystal structure ,Fourier transform infrared spectroscopy ,Wurtzite crystal structure ,Blueshift - Abstract
We have investigated the structural, optical and magnetic properties of Zn0.90Co0.10O, synthesized by the method of two electrode electrodeposition. X-ray diffraction measurement confirms the evolution of a single-phase polycrystalline hcp Wurtzite structure. Co-2p core-level XPS confirms that Co is present in mixed 2+ and 3+ states. The Fourier Transform Infrared (FTIR) spectrum findings substantiate the fact that a single-phase Hexagonal Wurtzite ZnO Crystal Structure has evolved. The SEM micrograph of the sample reveals smooth and dispersed morphology consisting of fine particles. The U-V visible NIR and PL spectroscopy measurements substantiate the fact that Co2+ has substituted Zn2+ in the matrix of ZnO which agrees with XRD findings. The sample shows good optical property and reveals a blue shift. It seems that the material is a potential candidate to be used as UV sensors. Room Temperature Intrinsic Ferromagnetism has been confirmed by VSM measurement.
- Published
- 2021
- Full Text
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42. Band-gap tunable (GaxIn1−x)2O3 layer grown by magnetron sputtering
- Author
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Juan Zhou, Haiou Li, Jinyu Sun, Xianghu Wang, Qi Li, Sun Tangyou, Liu Xingpeng, Daoyou Guo, Gongli Xiao, Zujun Qin, Fu Tao, Fabi Zhang, Xiuyun Zhang, and Rong Wang
- Subjects
Materials science ,Computer Networks and Communications ,Band gap ,business.industry ,Sputter deposition ,Blueshift ,Hardware and Architecture ,Signal Processing ,Transmittance ,Sapphire ,Optoelectronics ,Electrical and Electronic Engineering ,Thin film ,business ,Absorption (electromagnetic radiation) ,Monoclinic crystal system - Abstract
Multicomponent oxide (GaxIn1−x)2O3 films are prepared on (0001) sapphire substrates to realize a tunable band-gap by magnetron sputtering technology followed by thermal annealing. The optical properties and band structure evolution over the whole range of compositions in ternary compounds (GaxIn1−x)2O3 are investigated in detail. The X-ray diffraction spectra clearly indicate that (GaxIn1−x)2O3 films with Ga content varying from 0.11 to 0.55 have both cubic and monoclinic structures, and that for films with Ga content higher than 0.74, only the monoclinic structure appears. The transmittance of all films is greater than 86% in the visible range with sharp absorption edges and clear fringes. In addition, a blue shift of ultraviolet absorption edges from 380 to 250 nm is noted with increasing Ga content, indicating increasing band-gap energy from 3.61 to 4.64 eV. The experimental results lay a foundation for the application of transparent conductive compound (GaxIn1−x)2O3 thin films in photoelectric and photovoltaic industry, especially in display, light-emitting diode, and solar cell applications.
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- 2021
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43. Synthesis, structure, and optical properties of nanopowders CdS: xAl (x=0, 1, 5, 10, 15 and 20%) via the sol–gel technique
- Author
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E.M. Assim
- Subjects
Nanostructure ,Materials science ,Band gap ,law ,Scanning electron microscope ,Analytical chemistry ,Calcination ,Crystallite ,Nanocrystalline material ,Sol-gel ,Blueshift ,law.invention - Abstract
The nanocrystalline Al-doped CdS semiconductors were produced accurately by the sol-gel calcination process. The aluminum was added with different percent’s (0, 1, 5, 10, 15, and 20 wt%) to the synthesized CdS. Both FT-Raman analysis and UV–VIS-NIR absorption measurements were utilized to characterize the studied semiconductors' structural and optical characteristics. The detected X-ray diffraction (XRD) patterns of the prepared CdS present a polycrystalline structure, and Al-doping does not significantly impact this range. Optical bandgaps were determined for undoped and Al-doped CdS, showing a significant change with the percentage of Al-dopants. With increasing Al-doping up to (20 percent), the optical bandgap for CdS (2.38 eV) grows to reach (2.47 eV) and the allowed transitions were found to be direct for the investigated samples. The blue shift may be the reason for the optical bandgap variations. Scanning Electron Microscope (SEM) micrographs were performed to establish the Al-doped CdS nanostructure to identify the morphological characteristics.
- Published
- 2021
- Full Text
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44. Green Light Emitting Cadmium Sulfide Nanoparticles with Coral Surface Morphology
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K. V. Divya, Baby Thomas, E. Tomlal Jose, and Jacob K. Chacko
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Materials science ,Band gap ,Nanochemistry ,Nanoparticle ,General Chemistry ,Green-light ,Condensed Matter Physics ,medicine.disease_cause ,Biochemistry ,Cadmium sulfide ,Blueshift ,chemistry.chemical_compound ,Chemical engineering ,chemistry ,medicine ,General Materials Science ,Absorption (electromagnetic radiation) ,Ultraviolet - Abstract
Cadmium sulfide (CdS) is an important semiconductor material that has been utilized constructively for various modern applications. There were lot of works regarding the preparation of CdS nanoparticles. The present work has utilized a chemical precipitation method with and without using a capping agent. Even though the solvent system used for the preparation is a new one and provides a non-toxic reaction medium, this work mainly focused on the advantages of surface capping on nanoparticles. CdS nanoparticles prepared by surface capping with oleic acid (OA) exhibit many unique properties compared to the uncapped nanoparticles. The coral shaped surface morphology and the bright green fluorescence observed in OA capped CdS nanoparticles were not reported elsewhere. Strong absorption of radiation in the visible as well as in the ultraviolet region with a large band gap was also observed in capped CdS nanoparticles. Blue shift in emission with an intense peak was another unique character observed in the surface capped CdS nanoparticles. Morphological, structural, optical and thermal properties of the capped and uncapped CdS nanoparticles were systematically investigated.
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- 2021
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45. Reversing the Polarity of MoS2 with PTFE
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Saifei Gou, Peng Zhou, Tong Ye, Hanqi Liu, Jiong Ma, David Wei Zhang, Wenzhong Bao, Yawei Kong, Zhengzong Sun, and Kun Ba
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Materials science ,Photoluminescence ,Polarity (physics) ,business.industry ,Doping ,Fermi level ,Blueshift ,symbols.namesake ,chemistry.chemical_compound ,Semiconductor ,chemistry ,Monolayer ,symbols ,Optoelectronics ,General Materials Science ,business ,Molybdenum disulfide - Abstract
Pristine monolayer molybdenum disulfide (MoS2) demonstrates predominant and persistent n-type semiconducting polarity due to the natural sulfur vacancy, which hinders its electronic and optoelectronic applications in the rich bipolarity area of semiconductors. Current doping strategies in single-layer MoS2 are either too mild to reverse the heavily n-doped polarity or too volatile to create a robust electronic device meeting the requirements of both a long lifetime and compatibility for mass production. Herein, we demonstrate that MoS2 can be transferred onto polytetrafluoroethylene (PTFE), one of the most electronegative substrates. After transfer, the MoS2 photoluminescence exhibits an obvious blueshift from 1.83 to 1.89 eV and a prolonged lifetime, from 0.13 to 3.19 ns. The Fermi level of MoS2 experiences a remarkable 510 meV decrease, transforming its electronic structure into that of a hole-rich p-type semiconductor. Our work reveals a strong p-doping effect and charge transfer between MoS2 and PTFE, shedding light on a new nonvolatile strategy to fabricate p-type MoS2 devices.
- Published
- 2021
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46. Effect of Forster resonance energy transfer on the photoluminescence of PPy-ZnO composite
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Asit Kumar Kar and Smita Dey
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Photoluminescence ,Nanocomposite ,Materials science ,Absorption spectroscopy ,General Chemistry ,Condensed Matter Physics ,Emission intensity ,Acceptor ,Electronic, Optical and Magnetic Materials ,Blueshift ,Biomaterials ,Förster resonance energy transfer ,Chemical engineering ,Materials Chemistry ,Ceramics and Composites ,Absorption (electromagnetic radiation) - Abstract
The structural and optical properties of polypyrrole-ZnO (PPy-ZnO) composites with different amount of ZnO are investigated. The nature of optical absorption and emission of the composites having agglomerated granular morphology is explored. Addition of ZnO slightly affects the conjugation of the polymer chain due to which the π-π* transition of PPy-ZnO composite shows some blue shift in the UV-Vis absorption spectra. The photoluminescence intensity of PPy-ZnO nanocomposite varies with variation of ZnO content. This tunability in the photoluminescence intensity of PPy-ZnO nanocomposite can be understood in terms of Forster Resonance Energy transfer (FRET) from ZnO (donor) to PPy (acceptor). The energy transfer efficiency, Forster radius and separation between donor and acceptor are predicted theoretically by using a FRET model. With the change in donor concentration, the energy transfer efficiency changes which affects the emission intensity of composites. The highest emission intensity is observed for 1.22 g of ZnO which indicates the highest energy transfer between ZnO and PPy. Thus, by tuning ZnO content the emission properties of the PPy-ZnO composite can be tuned.
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- 2021
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47. Tuning the Optical Band Gap of Two-Dimensional WS2 Integrated with Gold Nanocubes by Introducing Palladium Nanostructures
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Chih-Kai Liao, Mahmoud A. Mahmoud, and Guanhua Wu
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Photoluminescence ,Materials science ,Absorption spectroscopy ,Band gap ,Schottky barrier ,Fermi level ,Tungsten disulfide ,Surfaces and Interfaces ,Condensed Matter Physics ,Photochemistry ,Blueshift ,symbols.namesake ,chemistry.chemical_compound ,chemistry ,Electrochemistry ,symbols ,General Materials Science ,Absorption (electromagnetic radiation) ,Spectroscopy - Abstract
The two characteristic absorption peaks of semiconducting two-dimensional tungsten disulfide (WS2) are red-shifted after integrating with gold nanocube (AuNC) arrays. The amount of the red shift is reduced when the AuNCs are coated with a high concentration of Pd. A negligible shift was observed in the absorption peaks of WS2 when smaller amounts of Pd are introduced to the surface of AuNCs. Conversely, the photoluminescence (PL) of WS2 is blue-shifted when measured on top of AuNCs and AuNCs coated with different amounts of Pd. AuNC-Pd Janus nanoparticles are prepared by depositing Pd atoms asymmetrically on AuNCs assembled into 2-D arrays on the surface of a glass substrate by the chemical reduction of Pd ions. Due to the large AuNC or AuNC-Pd/WS2 Schottky barrier, the plasmon-induced hot electron transfer (PHET) from AuNCs and AuNCs coated with a high concentration of Pd is responsible for the red shift of the absorption spectrum of WS2. Introducing a lower concentration of Pd to AuNCs increases the Schottky barrier further due to the formation of the Au-Pd equilibrium Fermi level of lower energy, reducing the efficiency of PHET. The effect of Pd on the Fermi level of AuNCs vanishes at high Pd deposition. Pauli blocking and phase-space filling are responsible for the blue shift of PL of WS2 on top of AuNCs and AuNCs coated with Pd. The Pauli blocking effect is directly proportional to the PHET efficiency. This explains the significant blue shift of PL of WS2 after integrating with AuNCs and AuNCs coated with a high concentration of Pd. Additionally, depositing Pd onto AuNCs elongates the lifetime of the hot electrons and enhances the PHET efficiency.
- Published
- 2021
- Full Text
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48. Tunable White Light-Emitting Devices Based on Unilaminar High-Efficiency Zn2+-Doped Blue CsPbBr3 Quantum Dots
- Author
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Zhanpeng Qin, Hongli Liu, Weigang Ding, Shuai Zhang, Xianggao Li, Guofu Zhou, Longfei Yuan, and Shirong Wang
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Photoluminescence ,Materials science ,Fabrication ,business.industry ,Doping ,Quantum yield ,Blueshift ,Wavelength ,Quantum dot ,Optoelectronics ,General Materials Science ,Physical and Theoretical Chemistry ,business ,Perovskite (structure) - Abstract
Perovskite-based white-light-emitting devices (WLEDs) are expected to be the potential candidate for the next-generation lighting field due to their scalability and low-cost process. However, simple and adjustable WLED fabrication technology is in urgent need. Here, WLEDs with a single layer of perovskite quantum dots (PQDs) were constructed by combining Zn2+-doped CsPbBr3 PQDs with exciplex emission between poly(9-vinylcarbazole) (PVK) and ((1-phenyl-1H-benzimidazol-2-yl)benzene)) (TPBi). Zn2+-doped CsPbBr3 PQDs with polar ion shells were prepared by means of low temperature and post-treatment. The photoluminescence quantum yield (PLQY) can reach as high as 95.9% at the emission wavelength of 456 nm. The blue shift of its PL (∼60 nm) is much greater than that of other reported Zn2+-doped CsPbBr3 PQDs (5-10 nm), thus realizing the true blue-emission Zn2+-doped CsPbBr3 PQDs. As a result, just by controlling the thickness of TPBi, the adjustment of cold (CIE (0.2531, 0.2502)) and warm WLEDs (CIE (0.3561, 0.3562)) is realized for the first time.
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- 2021
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49. Covalent Bonding Between Be+ and CO2 in BeOCO+ with a Surprisingly High Antisymmetric OCO Stretching Vibration
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Gernot Frenking, Mohua Chen, Chengxiang Ding, Qingnan Zhang, Mingfei Zhou, Lili Zhao, and Xuelin Dong
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Antisymmetric relation ,Infrared spectroscopy ,chemistry.chemical_element ,Charge (physics) ,General Chemistry ,Electronic structure ,Polarization (waves) ,Biochemistry ,Catalysis ,Blueshift ,Neon ,Crystallography ,Colloid and Surface Chemistry ,chemistry ,Covalent bond ,Physics::Chemical Physics - Abstract
The cationic complex BeOCO+ is produced in a solid neon matrix. Infrared absorption spectroscopic study shows that it has a very high antisymmetric OCO stretching vibration of 2418.9 cm-1, which is about 71 cm-1 blue-shifted from that of free CO2. The quantum chemical calculations are in very good agreement with the experimental observation. Depending on the theoretical method, a linear or quasi-linear structure is predicted for the cation. The analysis of the electronic structure shows that the bonding of Be+ to one oxygen atom induces very little charge migration between the two moieties, but it causes a significant change in the σ-charge distribution that strengthens the terminal C-O bond, leading to the observed blue shift. The bonding analysis reveals that the Be+ ← OCO donation results in strong binding due to the interference of the wave function and a charge polarization within the CO2 fragment and hybridization to Be+ but only negligible charge donation.
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- 2021
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50. Cesium Lead Bromide Perovskite Nanocrystals as a Simple and Portable Spectrochemical Probe for Rapid Detection of Chlorides
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Syed Akhil, Nimai Mishra, and Vishal Dutt
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SIMPLE (dark matter experiment) ,Materials science ,Photoluminescence ,chemistry ,Nanocrystal ,Ion exchange ,Caesium ,Inorganic chemistry ,chemistry.chemical_element ,General Chemistry ,Rapid detection ,Perovskite (structure) ,Blueshift - Published
- 2021
- Full Text
- View/download PDF
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