Synthesis of Fluorescent Ag Nanoclusters for Sensing and Imaging Applications

2018 ◽  
Vol 941 ◽  
pp. 2243-2248 ◽  
Author(s):  
Luca Burratti ◽  
Eleonora Bolli ◽  
Mauro Casalboni ◽  
Fabio de Matteis ◽  
Federico Mochi ◽  
...  
Keyword(s):  
Optical Properties ◽  
Optical Sensors ◽  
Bulk Material ◽  
Energy Levels ◽  
Silver Nanoclusters ◽  
Absorption Bands ◽  
Discrete Energy ◽  
Quantum Size ◽  
Transmission Electron ◽  
Bio Imaging

Metal nanoparticles have attracted more and more attention in the last years due to their unique chemical and physical properties which are very different from the metal bulk material. In particular, when the size of nanoparticles decreases below two nm, nanoparticles can be described as nanoclusters (NCs), and they present peculiar optical properties. The excited electrons in addition to specific absorption bands show also a bright luminescence related to the quantum size effect which produce discrete energy levels. Optical properties (absorption and fluorescence) of these NCs are widely used in many different applications in science and engineering, such as chemical sensors, fluorescent probes for bio imaging or in environmental issues. In the present study, we report on the synthesis of silver nanoclusters (AgNCs) in aqueous phase using silver nitrate as precursor salt and L-Glutathione (GSH) as stabilizer. AgNCs were characterized using absorption and fluorescence spectroscopy, and transmission electron microscopy (TEM). The strong absorption and luminescence shown by these NCs are very promising for a possible exploitation both as label for bioimaging and for optical sensors for heavy metal ions.

scholarly journals Fluorescent Silver Nanoclusters Embedded in Hydrogel Matrix and Its Potential Use in Environmental Monitoring

2021 ◽  
Vol 11 (8) ◽  
pp. 3470
Author(s):  
Luca Burratti ◽  
Fabio De Matteis ◽  
Roberto Francini ◽  
Joohyun Lim ◽  
Christina Scheu ◽  
...  
Keyword(s):  
Solid State ◽  
Optical Sensors ◽  
Silver Nanoclusters ◽  
Photochemical Synthesis ◽  
Glycol Diacrylate ◽  
Transmission Electron ◽  
Hydrogel Matrix ◽  
Bio Imaging ◽  
Poly Ethylene ◽  
Application Fields

The optical absorption and fluorescence of silver nanoclusters (AgNCs) are widely exploited in many different application fields such as sensors, bio-imaging, drug delivery, etc. In the sensor field, optical devices are highly versatile thanks to their ease of fabrication and low costs and, therefore, are optimal candidates to replace expensive apparatuses commonly used. In this study, we synthesized AgNCs in aqueous phase by photochemical synthesis using poly methacrylic acid (PMAA) as a stabilizer. Colloidal water solutions of these NCs showed a very good sensitivity to Pb(II) ions, and in order to fabricate a solid-state sensor, we introduced them in a hydrogel material formed by poly(ethylene glycol) diacrylate with a molecular weight of 700 g/mol (PEGDA700). The systems were characterized using absorption and fluorescence spectroscopy and transmission electron microscopy (TEM). Finally, the sensitivity to Pb(II) ions has been tested with the aim to use these systems as solid-state optical sensors for water quality.

Preparation, structural investigation and optical properties determination of composite films based on PAZO polymer doped with GeTe4-Cu chalcogenide particles

2021 ◽  
Author(s):  
Ani Stoilova ◽  
Dean Dimov ◽  
Yordanka Trifonova ◽  
Vanya Lilova ◽  
Blaga Blagoeva ◽  
...  
Keyword(s):  
Optical Properties ◽  
Structural Investigation ◽  
Bulk Material ◽  
Composite Films ◽  
Optical Absorption Coefficient ◽  
X Ray Diffraction ◽  
Transmission Electron ◽  
Reflectance Coefficient ◽  
Diode Pumped

The work presents preparation, structural investigation and optical properties characterization of composite films based on the azopolymer (poly[1-[4-(3-carboxy-4-hydroxyphenylazo)benzenesulfonamido]-1,2- ethanediyl, sodium salt]), shortly PAZO, doped with 1 wt.% particles of the previously synthesized by us new tellurium containing chalcogenide system (GeTe4)100-xCux, where x = 5, 10, 15 and 20 mol.%. X-Ray diffraction (XRD) was applied to analyze the structure of the chalcogenide bulk material. Transmission electron microscopy (TEM) has been used to study the particles and the composite films morphology. The transmittance coefficient (T), the reflectance coefficient (R), the refractive index (n), the extinction coefficient (k), the optical absorption coefficient (α) and the optical band gap (E_g^opt) of the composite films were determined. Birefringence was induced by a He-Cd laser with a wavelength 442 nm and measured with probe Diode Pumped Solid State (DPSS) laser at 635 nm. The influence of the dopants concentration on the optical performance of the composite films has been discussed.

The Structural and Optical Properties of Self-assembled InGaN/GaN Quantum Dots Grown by Molecular Beam Epitaxy

2006 ◽  
Vol 955 ◽  
Author(s):  
Tim Michael Smeeton ◽  
Mathieu Sénès ◽  
Katherine L Smith ◽  
Stewart E Hooper ◽  
Jon Heffernan
Keyword(s):  
Quantum Dots ◽  
Optical Properties ◽  
Molecular Beam Epitaxy ◽  
Molecular Beam ◽  
Light Emission ◽  
Structural And Optical Properties ◽  
Discrete Energy ◽  
Time Resolved ◽  
Transmission Electron ◽  
Z Contrast

ABSTRACTThe structural and optical properties of InGaN quantum dots grown by plasma-assisted molecular beam epitaxy (MBE) have been characterised using atomic force microscopy, high-resolution transmission electron microscopy (TEM), Z-contrast scanning TEM, micro-photoluminescence (PL), temperature dependent PL and time-resolved PL. The uncapped InGaN nano-islands have densities of ∼1.5 × 1011 cm−2, heights of (1.7 ± 1.0) nm and diameters of (10 ± 4) nm. These parameters are not substantially changed during overgrowth of a GaN cap and the resulting quantum dots have a composition of In0.15Ga0.85N. The observation of narrow luminescence peaks in micro-PL measurements proves light emission from discrete energy states and the optical properties indicate strong confinement of carriers in the quantum dots and an unusually weak impact of piezoelectric field effects.

Effects of germanium addition to copper phthalocyanine/fullerene-based solar cells

2012 ◽  
Vol 2 (2) ◽  
Author(s):  
Takeo Oku ◽  
Kazuma Kumada ◽  
Atsushi Suzuki ◽  
Kenji Kikuchi
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Optical Properties ◽  
Solar Cells ◽  
Copper Phthalocyanine ◽  
Energy Levels ◽  
Power Conversion ◽  
Analysis Data ◽  
Transmission Electron ◽  
Conversion Efficiencies

AbstractCopper phthalocyanine/fullerene-based solar cells were fabricated, and the electronic and optical properties were investigated. Effects of germanium addition to the solar cells were also investigated, which resulted in increase of power conversion efficiencies of the solar cells. Nanostructures of the solar cells were investigated by transmission electron microscopy and electron diffraction, which indicated formation of Ge compound nanoparticles in the copper phthalocyanine layers. Energy levels of the solar cells were discussed from the present analysis data.

Nanoparticles of Pd: Synthesis by Microwave-Solvothermal Method and Optical Properties

2008 ◽  
Vol 8 (8) ◽  
pp. 3930-3935 ◽  
Author(s):  
Dongsheng Li ◽  
Sridhar Komarneni
Keyword(s):  
Particle Size ◽  
Optical Properties ◽  
Pd Nanoparticles ◽  
Absorption Bands ◽  
Reaction Conditions ◽  
Transmission Electron ◽  
Vis Spectroscopy ◽  
Particle Size And Morphology ◽  
Particle Size And Shape ◽  
Size And Morphology

Well-dispersed Pd nanoparticles were synthesized by microwave-assisted solvothermal technique using methanol and ethanol. Particle size and morphology were controlled mainly by the reaction temperature. Particle size of Pd nanoparticles was controlled in the range of 2 to 11 nm by manipulating the reaction conditions. The Pd nanoparticles were characterized by transmission electron microscopy for particle size and shape and UV-Vis spectroscopy for optical properties. UV-Vis spectra showed that synthesized Pd nanoparticles stabilized with PVP had absorption bands at around 280 to 290 nm.

Electrical Conductivity of Quantum Size 2d Nanocomplex

2005 ◽  
Vol 23 ◽  
pp. 335-338 ◽  
Author(s):  
N. Gupta ◽  
H. Mallik ◽  
A. Sarkar
Keyword(s):  
Size Effect ◽  
Self Assembly ◽  
Energy Levels ◽  
Sol Gel ◽  
Quantum Size Effect ◽  
X Ray Diffraction ◽  
Distinctive Features ◽  
Quantum Size ◽  
Transmission Electron ◽  
Base Matrix

A nanocomplex of Chromium oxide nanoparticles with biopolymer matrix of gum Arabica is synthesized by natural self-assembly in chemical sol-gel route. Gum Arabica is chosen as base matrix due to its inherent biodegradable property. Experimental specimen of the said complex is prepared to satisfy near quantum size effect criterion. Due to near quantum size effect and spatial localization of nanoclusters, the developed specimen becomes an ideal 2D quantum well system. The longitudinal electrical conduction of the developed system is studied experimentally. Some of its structural aspects are also investigated to make the study conclusive. The dispersed cluster size is estimated by Transmission Electron Microscope (TEM) and X-ray diffraction (XRD). The results of I-V characteristics at temperatures 253 K show the distinctive features of localized energy levels. The spacing between energy levels near ground state to be comparable to the thermal energy at temperature 253 K for a cluster dimension below 10 nm. In this present study the developed specimens with the mentioned nanoclusters estimated from TEM and XRD as below 10 nm. The overall results are found to be encouraging.

scholarly journals Quantum Electrostatic Model for Optical Properties of Nanoscale Gold Films

Nanophotonics ◽  
2015 ◽  
Vol 4 (4) ◽  
pp. 413-418 ◽  
Author(s):  
Haoliang Qian ◽  
Yuzhe Xiao ◽  
Dominic Lepage ◽  
Li Chen ◽  
Zhaowei Liu
Keyword(s):  
Optical Properties ◽  
Optical Constants ◽  
Bulk Material ◽  
Gold Films ◽  
Electrostatic Model ◽  
Thin Gold Film ◽  
Electron Energy Level ◽  
Quantum Size ◽  
The Poisson Equation ◽  
Consistent Solution

AbstractThe optical properties of thin gold films with thickness varying from 2.5 nm to 30 nm are investigated. Due to the quantum size effect, the optical constants of the thin gold film deviate from the Drude model for bulk material as film thickness decreases, especially around 2.5 nm, where the electron energy level becomes discrete. A theory based on the self-consistent solution of the Schrödinger equation and the Poisson equation is proposed and its predictions agree well with experimental results.

scholarly journals Structural Evolution of Carbon Dots During Low Temperature Pyrolysis

Nanoscale ◽  
2022 ◽  
Author(s):  
Hui Luo ◽  
Leonardo Lari ◽  
Hyunjeong Kim ◽  
Servann Herou ◽  
Liviu Cristian Tanase ◽  
...  
Keyword(s):  
Optical Properties ◽  
Low Temperature ◽  
Carbon Dots ◽  
Energy Levels ◽  
Structural Evolution ◽  
Electronic States ◽  
Discrete Energy ◽  
Low Temperature Pyrolysis

Carbon dots (CDs) are an emerging class of photoluminescent material. Their unique optical properties arise from the discrete energy levels in their electronic states, which directly relate to their crystalline...

Chemical Control of Stress in Sol-Gel Derived Titania Films and Their Pressure Dependent Optical Properties

1988 ◽  
Vol 121 ◽  
Author(s):  
Wendy S. Frydrych ◽  
Gregory J. Exarhos ◽  
Kim F. Ferris ◽  
Nancy J. Hess
Keyword(s):  
Thin Films ◽  
Optical Properties ◽  
Bulk Material ◽  
Sol Gel ◽  
Applied Pressure ◽  
Transmission Electron ◽  
Gel Film ◽  
Diamond Anvil ◽  
Sputter Deposited ◽  
Sol Gel Films

ABSTRACTOptical properties and durability of thin films are influenced by strain which can be evaluated from frequency shifts of the lattice phonon lines in measured Raman spectra. The response of titania samples to applied pressure is reported in this work. Anatase and rutile samples of thin films (sol-gel and sputter deposited) and bulk materials have been subjected to hydrostatic pressures approaching 100 kbar in a diamond anvil cell. Results indicate that the rutile samples exhibit similar responses to applied pressure. Anatase sol-gel films exhibit a pressure-dependent response that suggests that the sol-gel film is more compressible than the bulk material, and a pressure-induced phase transformation observed for the bulk material is inhibited in the anatase sol-gel film. The anomalous pressure response of the anatase sol-gel film may result from the film microstructure which has been shown by transmission electron microscopy to consist of spheres of crystalline TiO2 surrounded by microscopic voids.

scholarly journals Synthesis, Structural and Optical Properties of TOPO and HDA Capped Cadmium Sulphide Nanocrystals, and the Effect of Capping Ligand Concentration

2015 ◽  
Vol 2015 ◽  
pp. 1-9 ◽  
Author(s):  
Damian C. Onwudiwe ◽  
Madalina Hrubaru ◽  
Eno E. Ebenso
Keyword(s):  
Optical Properties ◽  
Concentration Ratio ◽  
Cadmium Sulphide ◽  
Cds Nanoparticles ◽  
X Ray Diffraction ◽  
Structural And Optical Properties ◽  
One Pot ◽  
X Ray ◽  
Quantum Size ◽  
Transmission Electron

The thermal decomposition of bis(N,N-diallyldithiocarbamato)Cd(II) in a “one-pot” synthesis in tri-n-octylphosphine oxide (TOPO) and hexadecylamine (HDA) afforded CdS (TOPO-CdS and HDA-CdS) of varying optical properties and morphologies. The influence of the ratio of the precursor concentration to the capping molecule, as a factor affecting the morphology and size of the nanoparticles, was investigated. The particles varied in shape from spheres to rods and show quantum size effects in their optical spectra with clear differences in the photoluminescence (PL) spectra. The PL spectrum of the HDA capped CdS nanoparticles has an emission maximum centred at 468, 472, and 484 nm for the precursor to HDA concentration ratio of 1 : 10, 1 : 15, and 1 : 20, respectively, while the TOPO capped nanoparticles show emission peaks at 483, 494, and 498 nm at the same concentration ratio. Powdered X-ray diffraction (p-XRD) shows the nanoparticles to be hexagonal. The crystallinity of the nanoparticles was evident from high resolution transmission electron microscopy (HRTEM) which gave well-defined images of particles with clear lattice fringes.

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