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Mohamed H. Talaat

Bio: Mohamed H. Talaat is an academic researcher from Ain Shams University. The author has contributed to research in topics: Quantum dot & Bilayer graphene. The author has an hindex of 4, co-authored 5 publications receiving 135 citations.

Papers
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Journal ArticleDOI
TL;DR: Pulsed laser ablation in a liquid medium is a promising technique as compared to the other synthetic methods to synthesize different materials in nanoscale form and the particle size and distribution of materials can be adjusted.

75 citations

Journal ArticleDOI
TL;DR: In this article, a pulsed laser-assisted in liquid environment method has been developed successfully to synthesize size-tunable (5-12nm) and different shapes (sphere, rod, rope) of nano II-VI semiconductor (cadmium sulfide).
Abstract: A pulsed laser-assisted in liquid environment method has been developed successfully to synthesize size-tunable (5–12 nm) and different shapes (sphere, rod, rope) of nano II–VI semiconductor (cadmium sulfide). This method can be carried out in two ways; the first one is the top-down technique, which has been discussed in publications in the last few decades, and the other one is the bottom-up technique, which appears for the first time in this paper. X-ray diffraction, ultraviolet-visible spectroscopy, and transmission electron microscopy confirm that the nanoparticles are crystalline. The methods lead to the production of nanomaterials, which are important for photonics and biosensing applications. Both synthesized methods can be applied in all materials because of their ability to ablate almost all kinds of materials due to the ultrahigh energy density and control over the growth process by manipulating the process parameters such as intensity, wavelength, and so on.

66 citations

Journal ArticleDOI
TL;DR: In this article, the optical properties of low-buckled silicene and AB-stacked bilayer graphene quantum dots with zigzag edges subjected to an external electric field, which is normal to their surface, were investigated.
Abstract: We study numerically the optical properties of low-buckled silicene and AB-stacked bilayer graphene quantum dots with zigzag edges subjected to an external electric field, which is normal to their surface Within the nearest-neighbor approximation of the tight-binding model the optical absorption spectrum is calculated for quantum dots of triangular and hexagonal shapes In triangular silicene clusters a rich and widely tunable infrared absorption peak structure originates from transitions involving zero energy states The edge of absorption in silicene quantum dots undergoes red shift in the external electric field for triangular clusters, whereas blue shift takes place for hexagonal ones In small clusters of bilayer graphene the edge of absorption undergoes blue/red shift for triangular/hexagonal geometry

19 citations

Journal ArticleDOI
TL;DR: In this paper, the optical properties of low-buckled silicene and AB-stacked bilayer graphene quantum dots subjected to an external electric field, which is normal to their surface, were investigated.
Abstract: We study numerically the optical properties of low-buckled silicene and AB-stacked bilayer graphene quantum dots subjected to an external electric field, which is normal to their surface. Within the tight-binding model, the optical absorption is calculated for quantum dots, of triangular and hexagonal shapes, with zigzag and armchair edge terminations. We show that in triangular silicene clusters with zigzag edges a rich and widely tunable infrared absorption peak structure originates from transitions involving zero energy states. The edge of absorption in silicene quantum dots undergoes red shift in the external electric field for triangular clusters, whereas blue shift takes place for hexagonal ones. In small clusters of bilayer graphene with zigzag edges the edge of absorption undergoes blue/red shift for triangular/hexagonal geometry. In armchair clusters of silicene blue shift of the absorption edge takes place for both cluster shapes, while red shift is inherent for both shapes of the bilayer graphene quantum dots.

19 citations

Journal ArticleDOI
TL;DR: In this article, the optical properties of low-buckled silicene and AB-stacked bilayer graphene quantum dots subjected to an external electric field, which is normal to their surface, were investigated.
Abstract: We study numerically the optical properties of low-buckled silicene and AB-stacked bilayer graphene quantum dots subjected to an external electric field, which is normal to their surface. Within the tight-binding model, the optical absorption is calculated for quantum dots, of triangular and hexagonal shapes, with zigzag and armchair edge terminations. We show that in triangular silicene clusters with zigzag edges a rich and widely tunable infrared absorption peak structure originates from transitions involving zero energy states. The edge of absorption in silicene quantum dots undergoes red shift in the external electric field for triangular clusters, whereas blue shift takes place for hexagonal ones. In small clusters of bilayer graphene with zigzag edges the edge of absorption undergoes blue/red shift for triangular/hexagonal geometry. In armchair clusters of silicene blue shift of the absorption edge takes place for both cluster shapes, while red shift is inherent for both shapes of the bilayer graphene quantum dots.

3 citations


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Journal ArticleDOI
TL;DR: Unscreened surface charge of LSPC-synthesized colloids is the key to achieving colloidal stability and high affinity to biomolecules as well as support materials, thereby enabling the fabrication of bioconjugates and heterogeneous catalysts.
Abstract: Driven by functionality and purity demand for applications of inorganic nanoparticle colloids in optics, biology, and energy, their surface chemistry has become a topic of intensive research interest. Consequently, ligand-free colloids are ideal reference materials for evaluating the effects of surface adsorbates from the initial state for application-oriented nanointegration purposes. After two decades of development, laser synthesis and processing of colloids (LSPC) has emerged as a convenient and scalable technique for the synthesis of ligand-free nanomaterials in sealed environments. In addition to the high-purity surface of LSPC-generated nanoparticles, other strengths of LSPC include its high throughput, convenience for preparing alloys or series of doped nanomaterials, and its continuous operation mode, suitable for downstream processing. Unscreened surface charge of LSPC-synthesized colloids is the key to achieving colloidal stability and high affinity to biomolecules as well as support materials,...

892 citations

Journal ArticleDOI
TL;DR: The effects of substrate temperature on the structural, optical, medical and electrical characteristics of Cadmium Oxide (CdO) films are investigated in this article, where films are deposited on glass substrate at different temperatures, ranging between 450 and 600 oC, using Spray Pyrolysis Technique.
Abstract: The effects of substrate temperature on the structural, optical, medical and electrical characteristics of Cadmium Oxide (CdO) films are investigated in the current study. Films are deposited on glass substrate at different temperatures, ranged between 450–600 oC, using Spray Pyrolysis Technique. According to X–Ray Diffraction (XRD), it is found that the films are polycrystalline and Cadmium Oxide (CdO) is of a hexagonal wurtzite structure which the preferred direction of its crystal plane is (002). The maximum optical transmittance of films is more than 85%. The size of crystallites is calculated with the maximum value in 500o C. Furthermore, Cadmium Oxide (CdO) nanoparticles were synthesized in deionized water by laser ablation of Cadmium plate. In the current paper, the effects of laser pulse energy and wavelength on the characteristics of Cadmium Oxide (CdO) nanoparticles were studied. Analyses of Transmission Electron Microscope (TEM) were confirmed that size distribution of Cadmium Oxide (CdO) nanoparticles is reduced by increase in laser pulse energy. Fluorescence spectrum of Cadmium Oxide (CdO) nanoparticles shows violet emission accompanied by blue and green band. UV emission with high intensity shows that nanostructure of Cadmium Oxide (CdO) is of a little deficiency. Also, the current study aims to study the linear and non–linear optical characteristics of Cadmium Oxide (CdO) nanoparticles and their applications. Firstly, fluorescence spectrum, as a linear characteristics of Cadmium Oxide (CdO), as well as second harmonic generation and two photons absorption, as non–linear characteristics of Cadmium Oxide (CdO), are studied. Then, some aspects of medicinal and pharmaceutical applications of Cadmium Oxide (CdO) nanoparticles for eliminating cancer cells such as the effect of Cadmium Oxide (CdO) nanoparticles on DNA of human cancer cells and the interaction of Cadmium Oxide (CdO) nanoparticles with DNA of cancer cells are originally investigated. It should be noted that the range of considered parameters are separately clarified and explained in each of related sections (Figure 1).

159 citations

Journal ArticleDOI
TL;DR: In this article, a method to fabricate ultra-thin silver film up to 300nm on a quartz substrate using pulsed laser deposition technique from a pure silver plate target at room temperature with film thickness monitor to be applicable as a smart and portable nano-catalytic material, which could be used to degrade the hazard organic compounds.

109 citations

Journal ArticleDOI
TL;DR: In this paper, the physicochemical properties of polyvinyl alcohol (PVA) film were enhanced by embedding with nanostructured metal oxides (CdO, Al2O3, and Cu2O) via one-pot and green method, nanosecond Nd:YAG pulsed laser ablation in liquids technique.

93 citations

Journal ArticleDOI
TL;DR: In this article, the role of copper nanoparticles on modifying polyethylene oxide (PEO)/polyvinyl pyrrolidone (PVP)/Copper Oxide Nanoparticles (CuONPs) was demonstrated.
Abstract: Polyethylene Oxide (PEO)/Polyvinyl pyrrolidone (PVP)/Copper Oxide Nanoparticles (CuONPs) were synthesized by one-step Pulsed Laser Ablation of pure Copper plate immersed in PEO/PVP (70/30 wt.%) solution. PEO/PVP/CuONPs composite films were prepared using casting method. The role of copper nanoparticles on modifying PEO/PVP was demonstrated. The effect of different laser ablation times on the characterization of the prepared PEO/PVP/CuONPs composite films have been studied via XRD, UV–vis, PL, SEM, and Ac conductivity. XRD and SEM confirm the complexation between CuONPs and PEO/PVP matrix. The appearance of the characteristic absorption peak at 275 nm in UV–vis spectrum was attributed to the surface plasmon resonance (SPR) of CuONPs. The values of the direct and indirect optical band gap show a decreasing after doping PEO/PVP matrix by CuONPs. PL analysis confirmed that the existence of the CuO nanoparticles comprehensively reorders the delocalized n-electron system of PEO/PVP blend matrix. The behavior of dielectric constant and dielectric loss are progressively decreased as the frequency increased. The values of AC conductivity are increased as the laser ablation time increased. M ' and M″ values are increased by increasing the concentration of CuONPs in the PEO/PVP blend matrix, which induces an increase in the ion conduction of the prepared samples.

90 citations