scholarly journals Размерно-зависимые оптические свойства коллоидных квантовых точек CdS, пассивированных тиогликолевой кислотой

2018 ◽  
Vol 52 (9) ◽  
pp. 1015
Author(s):  
Т.С. Кондратенко ◽  
М.С. Смирнов ◽  
О.В. Овчинников ◽  
Е.В. Шабуня-Клячковская ◽  
А.С. Мацукович ◽  
...  
Keyword(s):  
Quantum Dots ◽  
Quantum Confinement Effect ◽  
Blue Shift ◽  
Luminescence Spectra ◽  
X Ray Diffraction ◽  
Excitation Spectra ◽  
Cubic Crystal ◽  
Luminescence Kinetics ◽  
Donor Acceptor ◽  
Colloidal Cds

AbstractThe results of studies of the optical properties of ensembles of colloidal CdS quantum dots passivated by thioglycolic acid are reported. The average dimensions of the quantum dots lie in the range from 1.7 to 5.8 nm. By X-ray diffraction studies and Raman spectroscopy, it is established that quantum dots crystallize with the formation of a cubic crystal lattice. The systematic features of the quantum-confinement effect in the optical absorption and luminescence spectra, as well as in the luminescence excitation spectra, are established. The features manifest themselves as a blue shift of the corresponding bands with decreasing quantum-dot dimensions. From analysis of the nanosecond luminescence kinetics, it is concluded that experimentally observed radiative recombination proceeds by the donor–acceptor mechanism.

Synthesis of Zn Doped CdSe Quantum Dots via Inverse Micelle Technique

2014 ◽  
Vol 807 ◽  
pp. 115-121 ◽  
Author(s):  
Fatihah Aplop ◽  
Mohd Rafie bin Johan
Keyword(s):  
Quantum Dots ◽  
Quantum Confinement Effect ◽  
Blue Shift ◽  
X Ray Diffraction ◽  
Cdse Qds ◽  
Xrd Pattern ◽  
Transmission Electron ◽  
Inverse Micelle ◽  
Cadmium Selenide Quantum Dots ◽  
The Fourier Transform

Zinc doped Cadmium Selenide Quantum Dots (CdSe/Zn QDs) were synthesized via inverse micelle technique. The absorption spectra exhibit a strong blue-shift characteristic due to quantum confinement effect. The X-ray Diffraction (XRD) pattern showed the zinc-blende phase of Zn doped CdSe QDs. Transmission Electron Microscopy (TEM) images suggested that the sizes of QDs were falls in range between 2 – 8 nm, with narrow size distribution. The TEM images also revealed that the Zn doped CdSe QDs were spherical, having a compact and dense structure. The optical bandgap of Zn-doped CdSe QDs are smaller than the undoped CdSe QDs as shown in Tauc’s plot. The fourier transform infrared spectra proves the complexion of CdSe-Zn QDs.

scholarly journals Optical Studies of Organically Functionalized Mn doped ZnS Quantum Dots

2021 ◽  
Vol 33 (12) ◽  
pp. 2972-2976
Author(s):  
Anju Bala ◽  
Rajeev Sehrawat ◽  
Renu Bala ◽  
Ashutosh Dixit
Keyword(s):  
Quantum Dots ◽  
Quantum Confinement Effect ◽  
Emission Spectra ◽  
Blue Shift ◽  
Capping Agent ◽  
X Ray Diffraction ◽  
Tem Analysis ◽  
Transmission Electron ◽  
Uv Visible ◽  
Mn Doped

Organically functionalized manganese doped zinc sulfide (ZnS/Mn) quantum dots were prepared by simple chemical method with polypyrrole (PPy) used as a capping agent. Prepared quantum dots were characterized with Fourier transform infrared spectroscopy (FTIR), high resolution transmission electron microscopy (HR-TEM), X-ray diffraction microscope (XRD), UV-visible spectroscopy and photoluminescence spectroscopy. Crystalline size of PPy capped ZnS/Mn quantum dots for various concentrations of PPy were approximate 2 nm as analyzed by XRD and TEM analysis. The absorption spectra revealed the occurrence of a blue shift in the peak of absorption and an increase in the band gap value due to the quantum confinement effect. FTIR spectroscopy confirmed that shifting of broad peak at 2335.8 cm–1 was due to S-H stretching vibrations, which confirmed interaction of hydrogen and sulphur in ZnS/Mn/PPy nanocomposites. Uncapped ZnS/Mn and PPy capped ZnS/Mn quantum dots reveal the effective photoluminescence emission spectra in the range of 300-700 nm. With increase the value of capping agent in ZnS/Mn quantum dots, photoluminescence spectra going to red shifting. The photoluminescence properties of the organically functionalized ZnS nanoparticles are favourable for the application in optoelectronic devices.

Modeling of the effect of bio-conjugation to anti-interleukin-10 antibodieson the photoluminescence of CdSe/ZnS quantum dots

2013 ◽  
Vol 1617 ◽  
pp. 145-150
Author(s):  
Tetyana V. Torchynska ◽  
Yuri V. Vorobiev ◽  
Paul P. Horley
Keyword(s):  
Quantum Dots ◽  
Ground State ◽  
Targeted Drug Delivery ◽  
Blue Shift ◽  
Interleukin 10 ◽  
Theoretical Description ◽  
Luminescence Spectra ◽  
Scientific Interest ◽  
Targeted Drug ◽  
Nano Medicine

ABSTRACTBio-conjugated CdSe/ZnS core/shell quantum dots (QDs) attract essential scientific interest due to their possible nano-medicine applications, including selective highlighting of affected tissues and targeted drug delivery to the certain type of cells. The paper is focused on the theoretical description of the blue shift observed in the luminescence spectra of CdSe/ZnS QDs upon their bio-conjugation with the anti-interleukin-10 antibodies. We propose a model that describes the ground state of the exciton confined in a quantum dot and explaining the bio-conjugation phenomenon by the change of the effective confinement volume.

Optical, Structural and Spectroscopic Characterization of ZnS Nanocrystals Embedded in KBr Single Crystal Matrix Grown by Czochralski Method

2021 ◽  
Vol 406 ◽  
pp. 274-284
Author(s):  
Soria Zeroual ◽  
Mohammed Sadok Mahboub ◽  
Ghani Rihia ◽  
Mourad Mimouni ◽  
Ghougali Mebrouk ◽  
...  
Keyword(s):  
Single Crystal ◽  
Absorption Edge ◽  
Quantum Confinement Effect ◽  
Blue Shift ◽  
Czochralski Method ◽  
Spectroscopic Characterization ◽  
Czochralski Growth ◽  
X Ray Diffraction ◽  
Crystal Matrix ◽  
Zns Nanocrystals

ZnS nanocrystals were embedded in a KBr single crystal matrix using the Czochralski growth technique. The X-ray diffraction, FT-IR and optical spectroscopy revealed the incorporation of ZnS nanocrystals. A blue shift of the absorption edge of the obtained samples has been observed, indicating the quantum confinement effect. The optical band-gap is estimated to be about 4.67 eV. Two excitonic peaks appeared at 300.4 nm and 271 nm. The average nanocrystal size was derived from the optical spectra. Annealing led to a shift in the absorption edge towards longer wavelengths and an increasing of the emissions intensity. Raman lines of the nanoparticles are broader and frequency-shifted compared to those of the bulk crystals. These results show that KBr is a good matrix-host of ZnS nanocrystals, and that the elaborated samples can be used for important technological applications.

scholarly journals Preparation and Characterization of Zno Nano particles Prepared by Hydrothermal Method

2019 ◽  
Vol 24 (3) ◽  
pp. 91
Author(s):  
Mohammed Ajmi Abd1 ◽  
Khalid Hamdi Razeg1 ◽  
Raad M.S Al-haddad2
Keyword(s):  
Quantum Confinement Effect ◽  
Hydrothermal Process ◽  
Blue Shift ◽  
Band Gap Energy ◽  
Zinc Nitrate ◽  
Nano Particles ◽  
Surface Topology ◽  
Nitrate Hexahydrate ◽  
X Ray Diffraction ◽  
Afm Analysis

In this study,the nanoparticles of zinc oxide were readily prepared  through Hydrothermal process by using zinc nitrate hexahydrate, and Sodium hydroxide as aprecursors. The surface topology, and crystalline structure of prepared ZnO nanoparticles were studied. X-ray diffraction (XRD) revealed that the prepared ZnO nano particles is highly crystalline, having (wurtzite) crystal structure.  The optical analysis by UV–vis showed that these ZnO nano particles have considerable blue shift in the optical band gap energy (Eg = 4.9eV), and this may be to the  quantum confinement effect of nano particles. The FT-IR results shows the  existence of OH, COO, H2O groups the characteristic vibrational modes of Zn–O were identified. and AFM analysis showed that the diameters of the ZnO particles is in ananometer range of (70-74)nm.   http://dx.doi.org/10.25130/tjps.24.2019.052 

scholarly journals New Insight into Titanium–Magnesium Ziegler–Natta Catalysts Using Photoluminescence Spectroscopy

2020 ◽  
Vol 74 (10) ◽  
pp. 1209-1218
Author(s):  
Valentina N. Panchenko ◽  
Anton I. Kostyukov ◽  
Anton Yu Shabalin ◽  
Evgeniy A. Paukshtis ◽  
Tatiana S. Glazneva ◽  
...  
Keyword(s):  
Magnesium Chloride ◽  
Molecular Complexes ◽  
Sample Surface ◽  
Photoluminescence Spectroscopy ◽  
Luminescence Spectra ◽  
Spectroscopic Methods ◽  
Excitation Spectra ◽  
Donor Acceptor ◽  
Diffuse Reflectance Infrared ◽  
Ziegler Natta Catalysts

This paper presents the results of study of titanium–magnesium catalysts often used in polymerization processes, by photoluminescence spectroscopy (PL) in combination with diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS). The interaction of dibutyl phthalate (DBP) with MgCl2 was studied at DBPadded/Mg = 0–1 (mol/mol). The luminescence spectra with excitation at 278 nm and the excitation spectra for main emission bands were recorded. It was shown that DBP adsorbed on magnesium chloride, both in the form of donor–acceptor complexes (D+A–) and in the form of molecular complexes. At DBPadded/Mg <0.15, the formation of D+A– complexes occur predominantly; with an increase in DBPadded/Mg, the fraction of molecular complexes increases. Molecular complexes are destroyed during the treatment of the support by TiCl4. In this case, the structure of magnesium chloride is disordered and new coordination–unsaturated sites are formed. This work is a first attempt to apply PL spectroscopy in combination with DRIFTS spectroscopy to study titanium–magnesium Ziegler–Natta catalysts. The application of PL spectroscopy to such systems made it possible to detect interactions within and between donor molecules, which would be particularly challenging to achieve using other spectroscopic methods. Both spectroscopic methods provided crucial information about the existence of two types of complexes on the sample surface which is important for tuning the synthesis procedure of the titanium–magnesium catalysts for olefin polymerization.

scholarly journals Aqueous synthesis of thioglycollic acid-capped Tb3+-doped cadmium sulfur quantum dots

2016 ◽  
Vol 7 ◽  
pp. 184798041668080
Author(s):  
Rongfang Wang ◽  
Xingming Wei ◽  
Pingfang Tao ◽  
Qinmin Wei ◽  
Pei Zhang ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Quantum Dots ◽  
Luminescence Properties ◽  
X Ray Diffraction ◽  
Rare Earth Ion ◽  
Aqueous Synthesis ◽  
Original Solution ◽  
Cubic Crystal ◽  
X Ray ◽  
Aqueous Method

Cadmium sulfur nanocrystals doped with the rare earth ion Tb3+ were synthesized using an easy aqueous method. Powder X-ray diffraction was used for the crystallography analysis of the nanocrystals. Results showed that cadmium sulfur: Tb3+ quantum dots had a cubic crystal structure. Effects of the pH of the original solution and Tb3+-dopant amount on luminescence properties of cadmium sulfur quantum dots were also systematically investigated. The luminescence properties of cadmium sulfur quantum dots were further improved using an appropriate Tb3+-dopant amount.

EFFECTS OF EXCESSIVE REACTANTS ON THE PROPERTIES OF CADMIUM SULFIDE THIN FILMS PREPARED BY CHEMICAL BATH DEPOSITION

2008 ◽  
Vol 07 (04n05) ◽  
pp. 279-282
Author(s):  
VORRADA LORYUENYONG ◽  
NOPPANUT RUANKUL ◽  
NATTAPON SUPSO ◽  
PONGSATORN CHUNPADUNGSUK
Keyword(s):  
Cadmium Sulfide ◽  
Chemical Bath Deposition ◽  
Quantum Confinement Effect ◽  
Ammonium Hydroxide ◽  
Complexing Agent ◽  
X Ray Diffraction ◽  
Cubic Crystal ◽  
Glass Substrates ◽  
Source Materials ◽  
Cds Films

Cadmium sulfide nanoparticles were synthesized and grown on glass substrates by chemical bath deposition. The method involves the preparation of aqueous solutions containing cadmium chloride ( CdCl 2) and thiourea [ CS ( NH 2)2] as source materials for cadmium and sulfur components, respectively. Ammonium hydroxide ( NH 4 OH )–ammonium chloride ( NH 4 Cl ) solution was used as a complexing agent in this study. The hexagonal and cubic crystal structure of as-deposited CdS films, determined by X-ray diffraction (XRD), is shown. The effects of Cd : S ratio variation on the surface morphology and optical properties of CdS films are also reported. The UV-vis transmission spectrum and SEM micrographs indicated that the Cd : S ratio in the aqueous solution had an impact on the band gap as well as the crystallite size and packing density of the CdS particles due to the quantum confinement effect.

Formation and Optical Properties of ZnSe Self-Assembled Quantum Dots in Cl-Doped ZnSe Thin Films Grown on GaAs (100) Substrates

2007 ◽  
Vol 124-126 ◽  
pp. 567-570
Author(s):  
G.N. Panin ◽  
H.J. Kim ◽  
S.Y. Kim ◽  
J.H. Jung ◽  
Tae Whan Kim ◽  
...  
Keyword(s):  
Quantum Dots ◽  
Quantum Confinement Effect ◽  
Blue Shift ◽  
Emission Peak ◽  
Band Edge ◽  
Near Band Edge ◽  
Band Edge Emission ◽  
Edge Emission ◽  
Acceptor Pair ◽  
Small Quantum

The high-resolution scanning electron microscopy (HRSEM) image showed that selfassembled ZnSe small quantum dots (QDs) and large nanodots with a pyramid shape were formed in the Cl-doped ZnSe epilayers grown on GaAs (100) substrates. The formation of the ZnSe QDs was attributed to three-dimensional growth controlled by distribution of the impurities in the Cldoped ZnSe epilayrs. Cathodoluminescence (CL) measurements at room temperature revealed the emission peak at 3.1 eV corresponding to the blue shift approximately 400 meV from the near band edge emission of 2.7 eV in the bulk ZnSe. The blue shifted CL peak indicates the quantum confinement effect resulting from the formation of the ZnSe QDs in the Cl-doped ZnSe thin film. While the peak position of the donor-acceptor pair emission shifted to higher energies with decreasing temperature, the band-edge emission peak for the QDs did not significantly change.

scholarly journals Structural and optical properties of NiO and Mn doped NiO nanparticles

2020 ◽  
Vol 1 (1) ◽  
pp. 20-30
Author(s):  
C. Thangamani ◽  
S.Revathi ◽  
P. Matheswaran ◽  
K. Pushpanathan
Keyword(s):  
Quantum Confinement Effect ◽  
Blue Shift ◽  
Precipitation Method ◽  
Average Crystalline Size ◽  
X Ray Diffraction ◽  
Structural And Optical Properties ◽  
Optical Microstructure ◽  
Mn Doped ◽  
Fcc Structure ◽  
Microstructure And Magnetic Properties

Ni1-xMnxO (x = 0.0 - 0.05) nanoparticles were successfully prepared by precipitation method at room temperature Prepared samples were characterized by structural, optical, microstructure and magnetic properties. X-ray diffraction analysis confirmed that Mn ions substitution of NiO lattice with FCC structure. The average crystalline size found to decrease from 42 to 34 nm. Optical analysis show increase in band from 4 -3.8 eV by strong quantum confinement effect with blue shift in the absorption spectra range of 325 – 290 nm. FTIR spectra confirmed the formation of Ni-Mn-O.

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