GROWTH AND CHARACTERIZATION OF CdS AND CdS:Ag LUMINESCENT QUANTUM DOTS DISPERSED IN SOLUTION

A fast-chemically capping method in aqueous solution was developed to synthesize CdS and CdS : Ag luminescent nanoparticles and particles with sizes between 2–4 nm. The achieving of well-dispersed and narrow-sized particles in colloidal solution and also, high stability of them using mercaptoethanol (ME) as a capping agent was established. Quantum confinement effect was observed in UV-vis absorption as well as in PL spectra. PL spectroscopy also showed green emission and Ag dopants caused a faster energy transfer between CdS inter-bands. XRD patterns exhibited that both cubic and hexagonal phases exist in solutions. Ultimately, TEM images captured from QDs displayed the shapes of nanoclusters which are almost spherical.

Download Full-text

Synthesis and characterization of N, O-donor Schiff base capped ZnS NPs as a sensor for fluorescence selective detection of Fe 3+, Cr 2+ and Cd 2+ ions

Modern Electronic Materials ◽

10.3897/j.moem.4.4.35062 ◽

2018 ◽

Vol 4 (4) ◽

pp. 151-162

Author(s):

Dasari Ayodhya ◽

Guttena Veerabhadram

Keyword(s):

Schiff Base ◽

Quantum Confinement ◽

Metal Ion ◽

Quantum Confinement Effect ◽

Precipitation Method ◽

Donor Ligand ◽

Zinc Sulfide Nanoparticles ◽

Co Precipitation ◽

Selective Sensor

We report the simple synthesis of zinc sulfide nanoparticles (ZnSNPs) by a co-precipitation method using Schiff base, (2-[(4-methoxy-phenylimino)-methyl]-4-nitro phenol) as a capping agent. Here, Schiff base is also used as N, O-donor ligand to control the morphology of NPs and fluorescence interactions. The formation of ZnSNPs and their optical, structural, thermal properties and morphologies were studied by means of UV–vis DRS, fluorescence, FTIR, XRD, SEM, TEM, zeta potential and TGA. The optical properties and quantum confinement effect of the products were confirmed by means of spectroscopic measurements. XRD and TEM image shows that the synthesized ZnSNPs have cubic structures with a diameter of about less than 10 nm. The prepared ZnSNPs exhibited as a selective probe detection of Fe3+, Cr2+ and Cd2+ ions by fluorometrically and the emission band which disappears in the presence of increasing concentrations of Fe3+, Cr2+ and Cd2+ ions. Based on the fluorescence quenching of the NPs in the presence of metal ion of interest, the feasibility of their determinations was examined according to the Stern-Volmer equation. Our work suggested that Schiff base capped ZnSNPs could be a potential selective sensor in the detection of heavy metal ions.

Download Full-text

ELECTROREFLECTANCE CHARACTERIZATION OF THE Ge/Si GROOVE ISLAND STRUCTURES

International Journal of Nanoscience ◽

10.1142/s0219581x03001413 ◽

2003 ◽

Vol 02 (04n05) ◽

pp. 369-373

Author(s):

YO-YU CHEN ◽

S. C. LIN ◽

C. R. LU ◽

C. T. CHIA ◽

H. H. CHANG

Keyword(s):

Optical Properties ◽

Quantum Confinement ◽

Transition Energy ◽

Quantum Confinement Effect ◽

Three Dimensional ◽

Optical Transitions ◽

Wetting Layer ◽

Dimensional Growth ◽

Electroreflectance Spectroscopy

The optical properties of Ge/Si groove island structures were investigated by the electroreflectance spectroscopy at various temperatures. Optical transitions involving the groove islands near the spectral range of 2~2.5 eV were observed. When the Ge growth temperature is decreased, the three-dimensional growth of the Ge island on the wetting layer is suppressed and the Ge/Si intermixing formation of stacking grooves in the Si layers is enhanced. The corresponding spectral intensity is increased and the transition energy is reduced due to the quantum confinement effect.

Download Full-text

Opto-Electronic Properties of Green Synthesized ZnS Nanostructures

International Journal of Nanoscience ◽

10.1142/s0219581x17600328 ◽

2018 ◽

Vol 17 (04) ◽

pp. 1760032

Author(s):

Sujata Deb ◽

P. K. Kalita ◽

P. Datta

Keyword(s):

Quantum Confinement ◽

Quantum Confinement Effect ◽

Blue Shift ◽

Cubic Phase ◽

Capping Agent ◽

X Ray Diffraction ◽

Chemical Route ◽

Transmission Electron ◽

Wet Chemical ◽

Green Capping Agent

ZnS nanostructures are synthesized by a wet chemical route using starch as green capping agent under nitrogen environment. The as-prepared nanostructures are characterized structurally, optically and electrically. X-ray diffraction (XRD) spectra confirm that the zinc sulfide (ZnS) nanoparticles have cubic phase (zinc blende). UV–Vis spectrum of the sample clearly shows that the absorption peak exhibits blue shift compared to their bulk counterpart, which confirms the quantum confinement effect of the nanostructures. Its photoluminescence (PL) spectrum shows near band gap emission at 392[Formula: see text]nm and extrinsic emission at 467[Formula: see text]nm. The particle sizes calculated from XRD and UV studies are in fair agreement with high resolution transmission electron microscopy (HRTEM) results. Starch is found to be a noble capping agent in bringing quantum confinement. The synthesis under nitrogen environment has been observed to produce quality products by reducing the oxide traces. Moreover, the I–V characteristics under dark and illumination show that ZnS can be more suitable as photodetector.

Download Full-text

Tunable Quantum Confinement Effect on Non-volatile Thin Film Polymer Memory Device

10.1557/proc-1134-bb05-04 ◽

2008 ◽

Author(s):

Augustin J. Hong ◽

Kang L. Wang ◽

Wei Lek Kwan ◽

Yang Yang ◽

Dayanara Parra ◽

...

Keyword(s):

Thin Film ◽

Quantum Confinement ◽

Quantum Confinement Effect ◽

Memory Device ◽

Confinement Effect ◽

Film Polymer ◽

Polymer Memory

Download Full-text

Formation of Luminescent Si Nanocrystals by High-Temperature Annealing of Ion-Beam-Sputtered Si/SiO2 Multilayers

MRS Proceedings ◽

10.1557/proc-775-p9.57 ◽

2003 ◽

Vol 775 ◽

Author(s):

Suk-Ho Choi ◽

Jun Sung Bae ◽

Kyung Jung Kim ◽

Dae Won Moon

Keyword(s):

Quantum Confinement ◽

Radiative Recombination ◽

Ion Beam ◽

Quantum Confinement Effect ◽

Visible Range ◽

Ion Beam Sputtering ◽

Transmission Electron ◽

Si Nanocrystals ◽

Beam Sputtering ◽

Microscopy Images

AbstractSi/SiO2 multilayers (MLs) have been prepared under different deposition temperatures (TS) by ion beam sputtering. The annealing at 1200°C leads to the formation of Si nanocrystals in the Si layer of MLs. The high resolution transmission electron microscopy images clearly demonstrate the existence of Si nanocrystals, which exhibit photoluminescence (PL) in the visible range when TS is ≥ 300°C. This is attributed to well-separation of nanocrystals in the higher-TS samples, which is thought to be a major cause for reducing non-radiative recombination in the interface between Si nanocrystal and surface oxide. The visible PL spectra are enhanced in its intensity and are shifted to higher energy by increasing TS. These PL behaviours are consistent with the quantum confinement effect of Si nanocrystals.

Download Full-text

2D Self-assembly and Electronic Characterization of Oxygen-Boron-Oxygen-Doped Chiral Graphene Nanoribbons

Chemical Communications ◽

10.1039/d1cc01901e ◽

2021 ◽

Author(s):

Lei Jin ◽

Nerea Bilbao ◽

Yang Lv ◽

Xiao-Ye Wang ◽

Soltani Paniz ◽

...

Keyword(s):

Edge Effects ◽

Self Assembly ◽

Quantum Confinement ◽

Graphene Nanoribbons ◽

One Dimensional ◽

The Past ◽

Different Types

Graphene nanoribbons (GNRs), quasi-one-dimensional strips of graphene, exhibit a nonzero bandgap due to quantum confinement and edge effects. In the past decade, different types of GNRs with atomically precise structures...

Download Full-text