scholarly journals The Effect of External Gaseous Environments on the Photoluminescence Intensity of Quantum-Dimensional Composite System

2015 ◽  
Vol 2015 ◽  
pp. 1-4 ◽  
Author(s):  
V. V. Danilov ◽  
A. I. Khrebtov ◽  
I. V. Shtrom ◽  
G. E. Cirlin ◽  
Yu B. Samsonenko
Keyword(s):  
Quantum Dots ◽  
Laser Irradiation ◽  
Composite System ◽  
Vibrational Energy ◽  
Core Shell ◽  
Photoluminescence Intensity ◽  
Continuous Laser ◽  
Luminescence Enhancement ◽  
Gaas Nanowires ◽  
Photoluminescence Enhancement

The luminescence properties of the composite system based on colloidal CdSe/ZnS core shell quantum dots and GaAs nanowires under continuous laser irradiation are investigated. The phenomenon of photoinduced luminescence enhancement under various gaseous environments is shown. In addition to the previously reported mechanisms of the photoluminescence enhancement, a new one which is connected to the quantum dots losses of vibrational energy during the collisions with molecules of external gases is proposed.

scholarly journals Investigation on photoluminescence quenching of CdSe/ZnS quantum dots by organic charge transporting materials

2015 ◽  
Vol 33 (4) ◽  
pp. 709-713 ◽  
Author(s):  
Qu Yuqiu ◽  
Zhang Liuyang ◽  
An Limin ◽  
Wei Hong
Keyword(s):  
Quantum Dots ◽  
Oxidation Potential ◽  
Core Shell ◽  
Photoluminescence Intensity ◽  
Dynamic Quenching ◽  
Photoluminescence Quenching ◽  
Time Resolved ◽  
Quenching Efficiency ◽  
Hole Transporting ◽  
Time Resolved Photoluminescence

AbstractThe effect of different organic charge transporting materials on the photoluminescence of CdSe/ZnS core/shell quantum dots has been studied by means of steady-state and time-resolved photoluminescence spectroscopy. With an increase in concentration of the organic charge transporting material in the quantum dots solutions, the photoluminescence intensity of CdSe/ZnS quantum dots was quenched greatly and the fluorescence lifetime was shortened gradually. The quenching efficiency of CdSe/ZnS core/shell quantum dots decreased with increasing the oxidation potential of organic charge transporting materials. Based on the analysis, two pathways in the photoluminescence quenching process have been defined: static quenching and dynamic quenching. The dynamic quenching is correlated with hole transporting from quantum dots to the charge transporting materials.

Synthesis and characterization of CdSe/ZnS core-shell quantum dots immobilized on solid substrates through laser irradiation

2012 ◽  
Vol 209 (11) ◽  
pp. 2201-2207 ◽  
Author(s):  
E. György ◽  
A. Pérez del Pino ◽  
J. Roqueta ◽  
B. Ballesteros ◽  
A. S. Miguel ◽  
...  
Keyword(s):  
Quantum Dots ◽  
Laser Irradiation ◽  
Synthesis And Characterization ◽  
Core Shell ◽  
Solid Substrates

scholarly journals Mesoporous Silica Modified Luminescent Gd2O3:Eu Nanoparticles: Physicochemical and Luminescence Properties

2018 ◽  
Author(s):  
Ali Aldalbahi ◽  
Mostafizur Rahaman ◽  
Anees Ansari
Keyword(s):  
Colloidal Stability ◽  
Vibrational Energy ◽  
Aqueous Media ◽  
Spherical Shape ◽  
Cubic Phase ◽  
Core Shell ◽  
Silica Layer ◽  
Photoluminescence Intensity ◽  
Shell Nanoparticles ◽  
The Core

Highly colloidal Eu-doped Gd2O3 nanoparticles(core-NPs) were synthesized by thermal decomposition via weak base at low temperature (150oC), subsequently, silica layers were deposited to increased colloidal stability, solubility, biocompatibility and no-toxicity at the environmental condition. XRD results indicate the highly purified, crystalline, single phase cubic phase Gd2O3 nanocrystals. TEM image shows the mesoporous thick silica layer was effectively coated over the core nanocrystals, which have irregular size with nearly spherical shape and a mean grain size is about 10-30 nm. Absorption spectra and zeta potential results in aqueous media revealed that solubility, colloidal stability, and biocompatibility character was enhanced from core to core-shell structure because of silica layer surface encapsulation. The samples demonstrate excellent photoluminescence properties (dominant emission 5D0→7F2 transition in red region at 610 nm) indicated the advantage to use in optical bio-detection and bio-labeling etc. The photoluminescence intensity of the silica shell modified core/shell nanoparticles were suppressed relatively core-nanoparticles, it indicates the multi-photon relaxation pathways arising from the surface coated high vibrational energy molecules of the silanol groups. The core/nSiO2/mSiO2 nanocrystals display strong emission (5D0→7F2) transition along with excellent solubility and biocompatibility, which may find promising applications in photonic based biomedical applications.

scholarly journals Усиление люминесценции квантовых точек вблизи слоя наночастиц Ag/SiO-=SUB=-2-=/SUB=-

2018 ◽  
Vol 44 (8) ◽  
pp. 35
Author(s):  
Л.Б. Матюшкин ◽  
А. Перцова ◽  
В.А. Мошников
Keyword(s):  
Quantum Dots ◽  
Plasmon Resonance ◽  
Shell Thickness ◽  
Composite System ◽  
Fold Increase ◽  
Core Shell ◽  
Core Diameter ◽  
Shell Type ◽  
Dielectric Shell

AbstractWe have studied the influence of monodisperse Ag/SiO_2 core–shell-type nanoparticles with a core diameter of 17 nm and a dielectric-shell thickness within 0–40 nm on the photoluminescence of CdSe/ZnS quantum dots (QDs) excited by laser at a wavelength corresponding to the plasmon resonance in Ag/SiO_2 nanoparticles. It is established that the intensity of QD luminescence in the composite system exhibits up to 8.7-fold increase.

Decay-to-Recovery Behavior and on–off Recovery of Photoluminescence Intensity from Core/Shell Quantum Dots

ACS Photonics ◽  
2017 ◽  
Vol 4 (7) ◽  
pp. 1691-1704 ◽  
Author(s):  
Sidney T. Malak ◽  
Young Jun Yoon ◽  
Marcus J. Smith ◽  
Chun Hao Lin ◽  
Jaehan Jung ◽  
...  
Keyword(s):  
Quantum Dots ◽  
Core Shell ◽  
Photoluminescence Intensity ◽  
Recovery Behavior

Silver nanoparticle film induced photoluminescence enhancement of near-infrared emitting PbS and PbS/CdS core/shell quantum dots: observation of different enhancement mechanisms

Nanoscale ◽  
2016 ◽  
Vol 8 (9) ◽  
pp. 4882-4887 ◽  
Author(s):  
H. Y. Liang ◽  
H. G. Zhao ◽  
Z. P. Li ◽  
C. Harnagea ◽  
D. L. Ma
Keyword(s):  
Quantum Dots ◽  
Silver Nanoparticle ◽  
Ag Nanoparticles ◽  
Near Infrared ◽  
Core Shell ◽  
Photoluminescence Enhancement ◽  
Silver Nanoparticle Film ◽  
Nanoparticle Film

A plasmon/fluorophore system consisting of Ag nanoparticles and near-infrared quantum dots (QDs) is investigated for photoluminescence (PL) enhancement.

Comparative Studies on the Aqueous Synthesis and Biocompatibility of L-Cysteine and Mercaptopropionic Acid Capped CdSe/CdS/ZnS Core/Shell/Shell Quantum Dots

2019 ◽  
Vol 19 (6) ◽  
pp. 3334-3342 ◽  
Author(s):  
D Sukanya ◽  
D. Muthu Gnana Theresa Nathan ◽  
R Mahesh ◽  
P Sagayaraj
Keyword(s):  
Quantum Dots ◽  
Hexagonal Wurtzite Structure ◽  
Water Soluble ◽  
Optical Measurements ◽  
Core Shell ◽  
Photoluminescence Intensity ◽  
Visible Absorption ◽  
Aqueous Synthesis ◽  
Mercaptopropionic Acid ◽  
Transmission Electron

Quantum dots have now become the most important candidates and widely exploited as promising architectures for use as diagnostic and imaging agents in biomedicine and as semiconductors in the electronics industry. This article emphasizes on the aqueous synthesis of water soluble CdSe/CdS/ZnS core/shell/shell quantum dots with L-cysteine and mercaptopropionic acid as capping agent and their observed properties have been compared. The biocompatibility of the assynthesized quantum dots have also been analyzed through the cytotoxicity study using MTT assay. The structural, morphological and optical properties of these quantum dots have been examined through X-ray diffraction (XRD), high resolution transmission electron microscopy (HRTEM), UV-Visible absorption spectroscopy (UV-Vis) and Photoluminescence spectroscopy (PL). The capping of L-cysteine and mercaptopropionic acid on the quantum dots has been confirmed from Fourier transform infrared spectroscopy (FTIR). XRD results demonstrated the formation of hexagonal wurtzite structure for L-cysteine and cubic zinc blende structure for mercaptopropionic acid capped CdSe/CdS/ZnS quantum dots. From the optical measurements, it is observed that there is a considerable increase in the photoluminescence intensity of L-cysteine capped quantum dots than MPA. The HRTEM images revealed the narrow size distribution and in addition, L-cysteine capped quantum dots were found to be more biocompatible than mercaptopropionic acid capped quantum dots which would provide new opportunities for applications in bioimaging and biolabelling.

Composite system based on CdSe/ZnS quantum dots and GaAs nanowires

2013 ◽  
Vol 47 (10) ◽  
pp. 1346-1350 ◽  
Author(s):  
A. I. Khrebtov ◽  
V. G. Talalaev ◽  
P. Werner ◽  
V. V. Danilov ◽  
M. V. Artemyev ◽  
...  
Keyword(s):  
Quantum Dots ◽  
Composite System ◽  
Gaas Nanowires

High-Temperature Synthesis of CdSe-Based Core/Shell, Core/Shell/Shell, and Core/Graded-Shell Nanoplatelets for Stable and Efficient Narrowband Emitters

2019 ◽  
Author(s):  
Aurelio A. Rossinelli ◽  
Henar Rojo ◽  
Aniket S. Mule ◽  
Marianne Aellen ◽  
Ario Cocina ◽  
...  
Keyword(s):  
Quantum Dots ◽  
High Temperature ◽  
Equilibrium Shape ◽  
Size Variation ◽  
Crystal Defects ◽  
Atomic Scale ◽  
Quantum Yields ◽  
Core Shell ◽  
Compositional Gradient ◽  
High Quality

<div>Colloidal semiconductor nanoplatelets exhibit exceptionally narrow photoluminescence spectra. This occurs because samples can be synthesized in which all nanoplatelets share the same atomic-scale thickness. As this dimension sets the emission wavelength, inhomogeneous linewidth broadening due to size variation, which is always present in samples of quasi-spherical nanocrystals (quantum dots), is essentially eliminated. Nanoplatelets thus offer improved, spectrally pure emitters for various applications. Unfortunately, due to their non-equilibrium shape, nanoplatelets also suffer from low photo-, chemical, and thermal stability, which limits their use. Moreover, their poor stability hampers the development of efficient synthesis protocols for adding high-quality protective inorganic shells, which are well known to improve the performance of quantum dots. <br></div><div>Herein, we report a general synthesis approach to highly emissive and stable core/shell nanoplatelets with various shell compositions, including CdSe/ZnS, CdSe/CdS/ZnS, CdSe/Cd<sub>x</sub>Zn<sub>1–x</sub>S, and CdSe/ZnSe. Motivated by previous work on quantum dots, we find that slow, high-temperature growth of shells containing a compositional gradient reduces strain-induced crystal defects and minimizes the emission linewidth while maintaining good surface passivation and nanocrystal uniformity. Indeed, our best core/shell nanoplatelets (CdSe/Cd<sub>x</sub>Zn<sub>1–x</sub>S) show photoluminescence quantum yields of 90% with linewidths as low as 56 meV (19.5 nm at 655 nm). To confirm the high quality of our different core/shell nanoplatelets for a specific application, we demonstrate their use as gain media in low-threshold ring lasers. More generally, the ability of our synthesis protocol to engineer high-quality shells can help further improve nanoplatelets for optoelectronic devices.</div>

LUMINESCENT DETERMINATION OF SUGAR IN NATURAL HONEY

2020 ◽  
Vol 0 (4) ◽  
pp. 29-32
Author(s):  
B.M. GAREEV ◽  
◽  
A.M. ABDRAKHMANOV ◽  
G.L. SHARIPOV ◽  
◽  
...  
Keyword(s):  
Quantum Dots ◽  
Laboratory Test ◽  
Aqueous Solutions ◽  
Analytical Method ◽  
Sugar Content ◽  
Carbon Quantum Dots ◽  
Photoluminescence Intensity ◽  
Sucrose Content ◽  
Natural Honey

The photoluminescence of carbon quantum dots synthesized from natural honey and mixtures of honey and sugar has been studied. An increase in the sugar content leads to a decrease in the photoluminescence intensity without changing the shape of the luminescence spectrum of these quantum dots aqueous solutions, which is associated with a decrease in the yield of their synthesis in the sugar presence. The discovered effect can be used to detect sugar in honey. When examining five different market samples of flower honey using this method, two of them showed a significant decrease in the photoluminescence intensity. A laboratory test for compliance with GOST 19792-2017 Standard requirements established an excess of the sucrose content in these samples. Luminescent determination of sugar in honey does not require complicated equipment and can be used to develop a new analytical method for determining the sugar content in counterfeit natural honey.

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