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In this work, for the first time, a density functional theory (DFT) based comprehensive theoretical study is performed on the surface electronic properties of Bi 2 Se 3 nanosheet in the presence of a surface capping layer as well as mechanical strain. The study systematically introduces a biaxial compressive and tensile strain up to 5 % in natural, Sb 2 Se 3 surface capped, and SbBiSe 3 surface capped Bi 2 Se 3 , and the subsequent effects on the electronic properties are assessed from the surface energy band (E-k) structure, the density of states (DOS), band edge energy and bandgap variations, surface conducting state localization, and Fermi surface spin-textures. The result demonstrates that the Sb 2 Se 3 and SbBiSe 3 surface capping layer delocalizes the surface Bloch states leading to inter-surface surface state hybridization through bulk and subsequent Dirac point annihilation with surface bandgap opening, and these effects is more prominent for Sb 2 Se 3 surface capping with a bandgap opening of ∼9 meV. The application of biaxial compressive strain (tensile stress) can further localizes the surface Bloch states and thereby mitigate the surface bandgap opening in surface capped Bi 2 Se 3. In contrast, the application of biaxial tensile strain (compressive stress) enhances the surface Bloch state delocalization leading to larger surface bandgap opening in surface capped Bi 2 Se 3 and even introduces surface bandgap in natural Bi 2 Se 3. The interplay of surface capping and strain also exhibits distinct influence on the spin-momentum locking, where the spin-chirality of the Fermi surface can be destroyed, restored, and even reversed through application of suitable biaxial strain in surface capped Bi 2 Se 3. In essence, this work presents an extensive theoretical and design-level insight into the surface capping and biaxial strain co-engineering in Bi 2 Se 3 , which can potentially facilitate different topological transport for modern optoelectronics, spintronics, valleytronics, bulk photovoltaics applications of engineered nanostructured topological materials in the future. [ABSTRACT FROM AUTHOR]

In this paper, polymer grafted nickel-doped iron oxide nanoparticles are fabricated via an easy, one-step and fast electrochemical procedure. In the deposition experiments, iron(II) chloride hexahydrate, iron(III) nitrate nonahydrate, nickel chloride hexahydrate, and dextran were used as the bath composition. Dextran grafted nickel-doped iron oxides (DEX/Ni-SPIOs) were synthesized with applying direct current (dc) of 10 mA cm–2. The magnetite crystal phase, nano-size, Ni doped content, and dextran grafting onto SPIOs were verified through X-ray powder diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, field-emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM) and thermogravimetric (TG) and differential scanning calorimetry (DSC) analyses. Magnetic evaluation through vibrating-sample magnetometer (VSM) proved that the DEX/Ni-SPIOs product have superparamagnetic behavior with exhibiting the high saturation magnetization and negligible Ms and Hci values. Based on the obtained results, it was confirmed that the prepared dextran grafted Ni-SPIOs have suitable physico-chemical and magnetic properties for both therapeutic and diagnostic aims.

Heliotropium crispum-mediated assembly of silver nanoparticles exhibit profound antibacterial and anti-biofilm effects against multiple drug-resistant bacteria, but its stability and biocompatibility remain a hurdle in commercialization. Herein, we adopted a surface chemistry-based steric repulsion approach to investigate the colloidal stability of H. crispum silver nanoparticles (HC-AgNPs) and determine its application as a commercial antibacterial formulation. Two primary silver nanoparticles (AgNPs) were synthesized, i.e., HC-AgNPs and citrate-HC-AgNPs initially, which were then modulated to assemble various derivatives of AgNPs using polyethylene glycol (PEG) and polyvinylpyrrolidone (PVP) as stabilizing agents. Various parameters were assessed to investigate the morphology, colloidal physio-chemistry, and surface capping using various analytical techniques, such as UV–Vis spectrophotometer, zeta–dynamic light scattering (DLS), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM, and transmission electron microscopy (TEM). Selective AgNPs were then screened on the basis of stability for up to 8 months, heat resistance at 100 °C, and bioactivity via MTT assay using HEP-2, MCF-7, and HCEC cell lines. The UV–Vis and electron microscope results revealed that HC-AgNPs confer near-spherical and slight triangular-shaped morphology and the size of all synthesized AgNPs is in the range of 400–450 nm. All AgNPs synthesized from HC-source have characteristic FTIR peaks recorded near 2931 cm−1, 1996 cm−1, and 825 cm−1. This study highlights promising evidence for the commercial application of HC-AgNPs as an antimicrobial agent. Additionally, it provides a methodology for modulating the surface capping of biological nanoparticles and assesses its corresponding effect on the stability. [ABSTRACT FROM AUTHOR]

Facet‐selective etching and deposition, as determined by the landscape of surface energy, represent two powerful methods for the transformation of noble‐metal nanocrystals into nanostructures with complex shapes or morphologies. This review highlights the use of these two methods, including integration of them, for the fabrication of novel monometallic and bimetallic nanostructures with enhanced properties. We start with an introduction to the role of surface capping in controlling the facet‐selective etching or deposition on the surface of Ag nanocrystals, followed by a case study of how to maneuver etching and deposition at different facets of Pd nanocrystals for the fabrication of nanoframes. We then introduce the use of galvanic replacement to accomplish selective etching and deposition on two different facets in an orthogonal manner, transforming Pd nanocubes into Pd−Pt octapods. By complementing galvanic replacement with a chemical reduction reaction, it is also feasible to control the rates of these two reactions for the conversion of Ag nanocubes into Ag@Ag−Au concave nanocubes and Ag@Au core‐shell nanocubes. These transformation methods not only greatly increase the shape diversity of metal nanocrystals but also offer nanocrystals with enhanced plasmonic and/or catalytic properties. [ABSTRACT FROM AUTHOR]

In this study, superparamagnetic iron oxide nanoparticles (SPIONs) are simply fabricated through a one-step electrodeposition method, and their in situ surface capping with dextran layer and crystal structure doping with zinc cations are simultaneously performed during their electrochemical synthesis. A simple conditions of room temperature, two-electrode electroplating, direct current synthesis and pH=6.7 were applied in the electrodeposition process. The fabricated SPIONs are characterized through Fourier transform infrared (FTIR) spectroscopy, X-ray powder diffraction (XRD), field-emission scanning electron microscopy (FE-SEM), vibrating sample manometer (VSM), thermogravimetric (TG) and differential scanning calorimetry (DSC) analyses. These analyses results indicated that the prepared SPIONs have particles with 15nm size. The magnetic characters i.e. saturation magnetization (Ms), remanence (Mr) and coercivity (Hci) values of the fabricated SPIONs were measured to be 51.75 emu g-1, 0.16 emu g-1 and 3.35 Oe, respectively. It was found that the dextran surface capped-, zinc doped-SPIONs are proper candidates for biomedical investigations. [ABSTRACT FROM AUTHOR]

In this paper, magnetic iron oxide nanoparticles capped with glucose/sucrose/starch have been synthesized though a simple and easy electrochemical method. In this method, OH- anions were produced via galvanostatic cathodic current on the cathode surface, and then reacted with metal cations (i.e. Fe2+, Fe3+ and Ni2+) to form Ni-doped Fe3O4 deposit. At the same electrochemical conditions, saccharides capped Ni-doped iron oxides were also synthesized from saccharide-added electrolyte. The prepared samples were specified using FESEM, XRD, VSM, FT-IR and thermal gravimetric analyses. The FT-IR, XRD and FE-SEM data approved the formation of Ni-doped Fe3O4 particles with size of 30 nm. In the TG profiles, the sharp weight loss (~15.5%wt.) at the temperatures of 150-300 oC proved the capping of iron oxide surfaces by saccharide layer. The measured magnetic data by VSM analyses indicated that the prepared samples exhibit high saturation magnetization and low remanence at the applied external fields, and have proper superparamagnetic characters. [ABSTRACT FROM AUTHOR]

The capping of a BaSi 2 film with amorphous Si (a-Si) is a key technology for the solar cell applications of BaSi 2 . In this study, we have investigated the two-step evaporation process of BaSi 2 to fabricate the BaSi 2 film capped with an a-Si layer on a Si(100) substrate. The deposition of Si is possible as the second step because a small amount of Si remains after the first BaSi 2 evaporation step. Raman and X-ray photoelectron spectroscopies show that a-Si is formed by the two-step evaporation on the sample surface while Ba and carbonate species are not present on the surface, which are detected when the BaSi 2 film is fabricated without the second step. Depth composition profiles determined by X-ray photoelectron spectroscopy clearly demonstrate the formation of the layered structure of a-Si and BaSi 2 . Owing to the a-Si capping, O concentration in the BaSi 2 film is lower than that without a-Si, as evidenced by the composition profiles and energy-dispersive X-ray spectroscopy results. In addition, the microwave-detected photoconductivity decay analysis shows that the carrier lifetime in the a-Si/BaSi 2 samples is similar to or slightly higher than the BaSi 2 film without a-Si layer possibly due to the surface passivation effect and the reduction of oxygen concentration. [ABSTRACT FROM AUTHOR]

Gold nanoparticles (GNPs) are widely used for medical purposes, both in diagnostics as well as drug delivery, and hence are prone to release and distribution in the environment. Thus, we have explored the effects of GNPs with two distinct surface capping (citrate and PVP), and three different sizes (16, 27, and 37 nm) at 0.01-, 0.1-, and 1-mg L concentrations on a predominant freshwater alga Scenedesmus obliquus in the sterile freshwater matrix. We have also investigated how an abundant metal ion from freshwater, i.e., Zn ions may modulate the effects of the selected GNPs (40 nm, citrate, and PVP capped). Preliminary toxicity results revealed that gold nanoparticles were highly toxic in comparison to zinc ions alone. A significant modulation in the toxicity of Zn ions was not noticed in the presence of GNPs. In contrast, zinc ions minimized the toxicity produced by GNPs (both CIT-37 and PVP-37), despite its individual toxicity. Approximately, about 42, 33, and 25% toxicity reduction was noted at 0.05-, 0.5-, and 5-mg L Zn ions, respectively, for CIT-37 GNPs, while 31% (0.05 mg L), 24% (0.5 mg L), and 9% (5 mg L) of toxicity reduction were noted for PVP-37 GNPs. Maximum toxicity reduction was seen at 0.05 mg L of Zn ions. Abbott modeling substantiated antagonistic effects offered by Zn ions on GNPs. Stability and sedimentation data revealed that the addition of zinc ions gradually induced the aggregation of NPs and in turn significantly reduced the toxicity of GNPs. Thus, the naturally existing ions like Zn have an ability to modulate the toxicity of GNPs in a real-world environment scenario. [ABSTRACT FROM AUTHOR]

Abstract: Peroxidase mimics composed of inorganic nanoparticles are expected to circumvent the inherent difficulties of natural peroxidases, and to provide enhanced performance in important applications such as diagnosis and imaging. Despite the reports of a variety of peroxidase mimics in the past decade, very limited progress has been made on improving their catalytic efficiency. The catalytic efficiencies of most previously reported mimics are only up to one order of magnitude higher than those of natural peroxidases. In this work, we demonstrate a highly efficient peroxidase—polyvinylpyrrolidone (PVP)‐capped Pt nanocubes of sub‐10 nm in size. These PVP‐capped Pt cubes are ≈200‐fold more active than the natural counterparts and exhibit a record‐high specific catalytic efficiency. In addition to the superior efficiency, the new mimic shows several other promising features, including excellent stabilities, well‐controlled uniformity in both size and shape, controllable sizes, and facile and scalable production. [ABSTRACT FROM AUTHOR]

Organic and polymer capping agents are prevailingly used in the synthesis of metal nanocrystals to render size and shape controls for desirable catalytic properties. A general assumption in the electrocatalysis field is that the capping agents block active sites and hinder catalytic turnover. However there have been a number of experimental results suggesting otherwise. Investigation of the fundamental correlations between the surface capping and the catalytic kinetics of metal nanoparticles is of paramount importance yet still remains challenging in large part due to structural changes induced by capping agent removal or synthesis using different capping agents. Our approach involves a unique catalyst system comprising of 1.7 nm Pt nanoparticles with and without various surface capping. We find that surface capping affects both activity and selectivity of electrocatalytic oxygen reduction reaction. The influences can be positive, neutral or negative. The five capping agents studied fall into three groups. Polyacrylic acid (PAA) and polyvinylpyrrolidone (PVP) cappings do not change the onset potential or product selectivity, but increase the catalytic current density. Sodium dodecyl sulfate (SDS) and tetradecyltrimethylammonium bromide (TTAB) cappings do not change the onset potential or product selectivity, but slightly decrease the catalytic current density. Oleylamine (OA) capping significantly decreases the onset potential and the catalytic current density as well as change the product selectivity by favoring a high percentage of 2-electron reduction. [ABSTRACT FROM AUTHOR]

In the present study, the toxicity of gold nanoparticles (Au NPs) was evaluated on various trophic organisms. Bacteria, algae, cell line, and mice were used as models representing different trophic levels. Two different sizes (CIT and CIT) and surface-capped (CIT-polyvinyl pyrrolidone (PVP)-capped) Au NPs were selected. CIT Au NP aggregated more rapidly than CIT Au NP, while an additional capping of PVP (CIT-PVP capped Au NP) was found to enhance its stability in sterile lake water medium. Interestingly, all the forms of NPs evaluated were stable in the cell culture medium during the exposure period. Size- and dose-dependent cytotoxicities were observed in both bacteria and algae, with a strong dependence on reactive oxygen species (ROS) generation and lactate dehydrogenase (LDH) release. CIT-PVP capped Au NP showed a significant decrease in toxicity compared to CIT Au NP in bacteria and algae. In the SiHa cell line, dose- and exposure-dependent decline in cell viability were noted for all three types of Au NPs. In mice, the induction of DNA damage was size and dose dependent, and surface functionalization with PVP reduced the toxic effects of CIT Au NP. The exposure to CIT, CIT, and CIT-PVP capped Au NPs caused an alteration of the oxidative stress-related endpoints in mice hepatocytes. The toxic effects of the gold nanoparticles were found to vary in diverse test systems, accentuating the importance of size and surface functionalization at different trophic levels. [ABSTRACT FROM AUTHOR]

Abstract: We find the stabilization effect of surface capping on the adsorption capacity and photocatalytic activity of Ag3PO4 in the recycling. The citrate anion complex (CAC) as the surface capping is confirmed to be constituted by citrate anion and silver citrate complex. The adsorption capacity of Ag3PO4 with CAC capping exhibits little increase in the subsequent cycle, whereas the one of the bare Ag3PO4 decreases by 25.8% for methylene blue (MB). The photocatalytic activity of Ag3PO4 with CAC capping is maintained, compared to marked 10% decrease of bare Ag3PO4 for degrading MB. [Copyright &y& Elsevier]

Visible light emitting ZnO quantum dots (QDs) were synthesized by a modified sol–gel method and in situ coated with the amino acid cysteine to modify their surface chemistry and govern the crystal growth process. Surface chelation by a hydrophilic thiol such as cysteine offered a fine control over the particle size and modulated the optical emission and its stability by reducing the density of surfacial oxygen deficiencies and also induced the formation of hierarchical nanostructures in the solution. TEM and XRD results confirmed the formation of mono-dispersed and spherical ZnO QDs in the size range 2.5–3.8 nm. The modulation of band gap energies was manifested in the visible emission of cysteine modified QDs, which was found to be remarkably stable for cell labeling applications, when compared to the photoluminescence of conventional ZnO QDs. [ABSTRACT FROM AUTHOR]

Abstract: In the present study we have synthesized CdS semiconducting quantum dots by reverse micelle method using dodecanthiol (C12H26S) as the capping agent. The synthetic medium consists of a quaternary water/Sodium dodecyl sulfate (SDS)/buta-1-ol/hexane microemulsion. The size of the particles was controlled by changing the molar ratio W=[H2O]/[SdS], where [H2O] and [SdS] are the molar concentrations in hexane of water and SdS respectively. The CdS nanoparticles were embedded in a new PPV derivate named Fluorinated Bisphenol A P-phenylenevinylene (BPAF-PPV). Fourier transform infrared spectroscopy (FT-IR) showed a strong interaction of thiol groups with CdS nanoparticles. Blue shift of the optical absorption onset is observed due to quantum size effect. The band gap and particle sizes of the nanoparticles were deduced from optical absorption spectra and the use of an effective mass approximation (EMA) model. Photoluminescence spectroscopy evidenced a charge transfer process via the interface between BPAF-PPV/CdS nanoparticles. [Copyright &y& Elsevier]

Abstract: Light-emission and optical gain in a silicon-based material is an intensely studied scientific topic due to its possible application impact. In this article, we study colloidal dispersion of silicon nanocrystals with methyl-based capping. Excellent optical properties of this material include reasonably high luminescence quantum yield (20%) and fast radiative lifetime (10ns), comparable to direct-bandgap semiconductors. Moreover, luminescence maximum situated in the yellow spectral region (570nm) indicates lowered free-carrier absorption. Photoluminescence and FTIR measurements combined with ultrafine filtration show that the nanocrystals are dispersed in the solvent as single particles or small clusters, implying that scattering-related losses are also nearly eliminated. [Copyright &y& Elsevier]

Abstract: Based on mussel-inspired chemistry, a facile method was developed to prevent the leaching of enzyme from mesoporous silica supports, thus achieving high loading and enhanced stability of immobilized enzyme. More specifically, two approaches to enzyme-containing polydopamine (PDA)-silica hybrid materials were explored. One was to directly dip the enzyme-loaded bimodal mesoporous silica (BMS, 2–3nm and 10–50nm) spheres into the dopamine solution, acquiring enzyme-loaded PDA-filled BMS. Another was to first deposit a polyelectrolytes layer onto outer surface of enzyme-loaded BMS spheres and then dip into dopamine solution, acquiring enzyme-loaded PDA-capped BMS. Using catalase (CAT) as model enzyme, both CAT-loaded PDA-filled and PDA-capped BMS spheres displayed high loading and enhanced stability due to effective suppression of the enzyme leakage and drastic preservation of the catalytic activity. For example, ∼90mg CAT could be loaded in 1g of BMS after dopamine treatment with less than 5% loss in activity under rigorous stirring for 6h, as compared to over 60% loss in activity for CAT adsorbed on BMS without treatment. CAT loaded in PDA-filled or PDA-capped BMS spheres showed 61.7% and 78.1% of relative activities, respectively. [Copyright &y& Elsevier]

Efficient catalysts for the nitration of benzene are prepared by surface capping of Ag nanoparticles using glycerol and urea with their subsequent loading over anatase titania. Herein glucose was used as an environmentally benign reducing agent for the silver ions. The catalyst was characterized and its catalytic activity was evaluated in the low temperature preparation of nitrobenzene. Ag nanoparticle loading gives rise to improved performance when compared to bare anatase titania. The influence of stabilizers and the percentage metal loading of Ag on the catalytic activity was investigated. The increased reactivity of titania seen after Ag nanoparticle loading may be due to the presence of highly dispersed nano sized surface capped Ag. Among the two capping agents studied, glycerol provides maximum efficiency for a short reaction time. These new generation catalysts appear to be an efficient alternative for the conventional use of environmentally hazardous sulfuric acid catalyst. The side reactions are found to be minimal over the present catalytic systems which lead to excellent nitrobenzene selectivity. [ABSTRACT FROM AUTHOR]

Abstract: Semiconductors in the form of composite yields immense possibilities for the study of charge transfer processes at the interface. We have designed CdS nanoparticles (NPs) capped ZnO nanostructures using two morphologies of the latter namely nanorods arrays (NRAs) and nanocrystalline film to form a composite NRAs and composite films respectively. The photocurrent values in both the composites have been increased but to a different extent when these are illuminated with the ultraviolet (UV) light. More interestingly, the resultant UV photosensitivity in the composite NRAs is decreased while that in the composite films is increased as compared to the values of the respective uncapped samples. A different charge transfer process at the interface is occurred due to the difference in the morphologies resulting in a contrast change in the UV sensitivity. The photoluminescence results also show that the change in the emission property is morphology-dependent. Therefore, our results imply that the choice of the morphology while making a nanocomposite is crucial to tune its UV sensitivity as well as optical properties. [Copyright &y& Elsevier]

Gold nanoparticles protected by the self-assembled monolayers of 9-[6-(N,N-dibutyl-amino-dithiocarbamate)-hexyl]-carbazole, CHBDTC in short, were prepared via a phase-transfer method. These surface-modified nanoparticles were characterized with UV-vis, photoluminescence spectroscopy and TEM. It was found that the CHBDTC-capped gold nanoparticles were stable under ambient conditions, which is attributed to the protection of the CHBDTC densely packed on the gold nanoparticle surface. The fluorescence emission spectra indicated that the fluorescence of CHBDTC was quenched to some extent by gold nanoparticles. And the CHBDTC-capped Au nanoparticles could be promisingly applied as biomolecular labels and in fabrication of novel photo-based nanodevices as well, owing to the photoactive sensitivity of CHBDTC. [ABSTRACT FROM AUTHOR]

Surface capped CdSe nano-crystals (NCs) have been synthesized from cadmium acetate and octeno-1,2,3-selenadiazole in tri-octylphosphine (TOP). Well dispersed CdSe nano-particles showed an absorption band at 522 nm (2.36 eV) and emissions at 525 nm at an excitation wavelength of 450 nm, revealing near band-gap emission from isolated crystals. Broadened X-ray diffraction (XRD) pattern revealed cubic crystal structure of CdSe with crystallite size of less than 10 nm. X-ray photoelectron spectroscopy (XPS) showed that nano-crystals are air-stable and the presence of TOP around the particles was confirmed by infra-red (IR) spectroscopy. [ABSTRACT FROM AUTHOR]

Abstract: Copper sulfide nanoparticles surface-capped with self-assembled monolayer of N,N-dioctyldithiocarbamates were prepared in the presence of cetyltrimethylammonium bromide (CTAB) under different concentrations. The morphology and structure of the resulting copper sulfide nanoparticles were analyzed by XRD, XPS, TEM and FTIR. It was found that CTAB played a critical role in controlling the morphology and radius of the surface-capped copper sulfide nanoparticles during the synthesis process. [Copyright &y& Elsevier]

Abstract: Nickel nanoparticles surface-capped with self-assembled monolayer of dodecanethiol were prepared by the controlled reduction of nickel chloride (NiCl2·6H2O) in the presence of dodecanethiol of different concentrations as the ligand and hydrazinium hydroxide as the reductant. The morphology and structure of the resulting surface-capped nickel nanoparticles were analyzed by means of transmission electron microscopy, X-ray photoelectron spectroscopy, X-ray diffraction, Fourier transformation infrared spectroscopy and thermogravimetric analysis. It was found that dodecanethiol played a critical role in controlling the radius and dispersibility of the surface-capped Ni nanoparticles. Namely, the nickel nanoparticles prepared in the absence of the surface-capping agent were liable to aggregate, while those prepared in the presence of decanethiol with a large enough concentration had a very small grain size. It was supposed that the surface-capped nickel nanoparticles with significantly increased stability and dispersibility as compared to the non-surface-capped nickle nanoparticles could be used as a kind of novel nanoscale lubricating additives. [Copyright &y& Elsevier]

Cobalt disulfide is an important nanomaterial in the field of material chemistry due to its interesting catalytic and electromagnetic properties. We herein report the simple solution phase preparation of nanoparticles of cobalt disulfide in micellar medium of cationic surfactant cetyltrimethylammonium bromide (CTAB) and also by way of capping with thiophenol. The product has been characterized using spectroscopic and electron microscopic and magnetic moment measurements. The presence of disulfide bond is clearly evident from the 480 cm−1 peak in the infrared spectrum. The thiol passivated particles prepared in aqueous and ethanol medium has been found to have different compositions as observed from the ESIMS study. [ABSTRACT FROM AUTHOR]

Abstract: ZnS:Cu nanocrystals were prepared by solution synthesis technique in this study, and the systematic investigation was carried out for the surface capping effect in which the particle size could be controlled and the particle agglomeration could be reduced. The optical characteristics such as photoluminescence (PL) intensity and emission wavelength were also enhanced with surface capping. Sodium polyphosphate (SPP) was used as the surface capping agent, and the new results about the effects of SPP capping on structural and optical properties of ZnS:Cu nanocrystals were obtained as follows. ZnS nanoparticles had the cubic structure (β-ZnS), and the crystal structure was not changed with the input of SPP. The particle morphology was spherical, and grain size was decreased and particle agglomeration was reduced with an increase of SPP input amount. The position of UV absorption edge was found to depend upon the SPP input amount, and it was decreased from 340 to 280nm with the increase of SPP from 0.0 to 1.89g, clearly showing the remarkable blue-shift phenomenon. PL intensities were also dependent upon the amount of capping agent, and the highest PL intensity was obtained for the sample capped with SPP 1.13g in this study. PL emission wavelength was also blue-shifted, and it was decreased from 518 to 462nm with the increase of SPP from 0.0 to 1.89g. [Copyright &y& Elsevier]

Nearly mono-disperse high quality quantum dots (QDs) of zinc selenide have been synthesized by organometallic route that includes use of well known surfactants such as a carboxylic acid and trioctylphosphine (TOP). Single-step synthesis was performed at a temperature that is lower than many reported methods for such quantum dots of semiconductors. UV-Visible spectra of series of experiments showed steep absorption band at about 418 nm (Eg=∼3.0 eV). Photoluminescence measurement revealed band-edge emission at ∼431 nm from the ZnSe QDs. The particle size was found to be between 3-5 nm as calculated by Scherrer equation at <111> crystal plane of the hexagonal crystal structure of ZnSe. Particle size-distribution by dynamic light scattering technique showed narrow-size distribution of the particles within 10 nm. The particles are highly re-dispersible in organic solvents such as n-hexane and toluene thus making the dots useful for opto-electronic devices. [ABSTRACT FROM AUTHOR]