Width of the excitonic absorption peak and size of CdSxSe1−x semiconductor nanocrystallites

1992 ◽  
Vol 151 (1-2) ◽  
pp. 95-101 ◽  
Author(s):  
M. Ferrari ◽  
B. Champagnon ◽  
M. Barland
Keyword(s):  
Absorption Peak ◽  
Excitonic Absorption ◽  
Excitonic Absorption Peak

scholarly journals CdSe/ZnS Quantum Dots As a Fluorescence Probes For Determination of Vitamin B1

2021 ◽  
Author(s):  
Reza Tirbandpaya ◽  
Abdolraouf Samadi-Maybodi
Keyword(s):  
Quantum Dots ◽  
Limit Of Detection ◽  
Vitamin B1 ◽  
Fluorescence Probes ◽  
Fast Method ◽  
Excitonic Absorption ◽  
Wet Chemical ◽  
Excitonic Absorption Peak

Abstract This paper presents a new and fast method for determination of vitamin B1 (thiamine) using functionalized CdSe/ZnS quantum dots (QDs) as a sensor. In this study the core-shell CdSe/ZnS QDs with thioglycolic acid capping agents were synthesized by wet chemical method in aqueous solution. Electronic absorption was applied for size determination of the QDs, the average diameters of the synthesized quantum dots were calculated using wavelength of the first excitonic absorption peak. The methods of FESEM and FTIR were also used for characterization of the prepared samples. The results indicated that vitamin B1 could effectively quench the QDs emission and the fluorescence intensity decreased linearly with the concentration of vitamin B1 ranging from 10-7 to 10-4 molL−1 with limit of detection of 2×10-8 mol L−1. Determination of vitamin B1in pills from two pharmaceutical companies were used as real samples using this method .

Single-peak-regulation and wide-angle dual-band metamaterial absorber based on hollow-cross and solid-cross resonators

2020 ◽  
Vol 91 (3) ◽  
pp. 30901
Author(s):  
Yibo Tang ◽  
Longhui He ◽  
Jianming Xu ◽  
Hailang He ◽  
Yuhan Li ◽  
...  
Keyword(s):  
Transverse Electric ◽  
Surface Current ◽  
Dielectric Substrate ◽  
Transverse Magnetic ◽  
Metamaterial Absorber ◽  
Absorption Peak ◽  
Dual Band ◽  
Single Peak ◽  
Wide Angle ◽  
Surface Current Density

A dual-band microwave metamaterial absorber with single-peak regulation and wide-angle absorption has been proposed and illustrated. The designed metamaterial absorber is consisted of hollow-cross resonators, solid-cross resonators, dielectric substrate and metallic background plane. Strong absorption peak coefficients of 99.92% and 99.55% are achieved at 8.42 and 11.31 GHz, respectively, which is basically consistent with the experimental results. Surface current density and changing material properties are employed to illustrate the absorptive mechanism. More importantly, the proposed dual-band metamaterial absorber has the adjustable property of single absorption peak and could operate well at wide incidence angles for both transverse electric (TE) and transverse magnetic (TM) waves. Research results could provide and enrich instructive guidances for realizing a single-peak-regulation and wide-angle dual-band metamaterial absorber.

Synthesis and Characterization of Nanocrystalline ZnO Powders by a Direct Thermal Decomposition Route Using Zinc Nitrate Hexahydrate

2013 ◽  
Vol 770 ◽  
pp. 68-71 ◽  
Author(s):  
Supphadate Sujinnapram ◽  
Uraiphorn Termsuk ◽  
Atcharawan Charoentam ◽  
Sutthipoj Sutthana
Keyword(s):  
Thermal Decomposition ◽  
Crystallization Temperature ◽  
Zinc Nitrate ◽  
Zinc Nitrate Hexahydrate ◽  
Absorption Peak ◽  
Synthesis And Characterization ◽  
Nitrate Hexahydrate ◽  
Different Temperatures ◽  
Zno Powders

The nanocrystalline ZnO powders were synthesized by a direct thermal decomposition using zinc nitrate hexahydrate as starting materials. The precursor was characterized by TG-DTA to determine the thermal decomposition and crystallization temperature which was found to be at 325 oC. The precursors were calcined at different temperatures of 400, 500, and 600°C for 4 h. The structure of the prepared samples was studied by XRD, confirming the formation of wurtzite structure. The synthesized powders exhibited the UV absorption below 400 nm (3.10 eV) with a well defined absorption peak at around 285 nm (4.35 eV). The estimated direct bandgaps were obtained to be 3.19, 3.16, and 3.14 eV for the ZnO samples thermally decomposed at 400, 500, and 600°C, respectively.

Fractional-dimensional excitonic absorption theory applied toV-groove quantum wires

2004 ◽  
Vol 70 (15) ◽  
Author(s):  
K. F. Karlsson ◽  
M.-A. Dupertuis ◽  
H. Weman ◽  
E. Kapon
Keyword(s):  
Quantum Wires ◽  
Excitonic Absorption ◽  
Absorption Theory

scholarly journals Moiré Angle Dependent Excitonic Absorption in Twisted Bilayer WSe2 by EELS

2021 ◽  
Vol 27 (S1) ◽  
pp. 122-123
Author(s):  
Steffi Woo ◽  
Robert Schneider ◽  
Johann Preuß ◽  
Ashish Arora ◽  
Benjamin Carey ◽  
...  
Keyword(s):  
Excitonic Absorption

Transparent P-type Conducting LaCuOS Layered Oxysulfide

2001 ◽  
Vol 666 ◽  
Author(s):  
Kazushige Ueda ◽  
Shin-ichiro Inoue ◽  
Sakyo Hirose ◽  
Hiroshi Kawazoe ◽  
Hideo Hosono
Keyword(s):  
Electrical Conductivity ◽  
Visible Region ◽  
Optoelectronic Devices ◽  
Promising Material ◽  
High Transparency ◽  
Conducting Oxides ◽  
Excitonic Absorption ◽  
Type Semiconductor ◽  
Optical Applications ◽  
P Type

ABSTRACTMaterials design for transparent p-type conducting oxides was extended to oxysulfide system. LaCuOS was selected as a candidate for a transparent p-type semiconductor. It was found that the electrical conductivity of LaCuOS was p-type and controllable from semiconducting to semi-metallic states by substituting Sr2+ for La3+. LaCuOS films showed high transparency in the visible region, and the bandgap estimated was approximately 3.1 eV. Moreover, it was revealed that LaCuOS showed sharp excitonic absorption and emission at the bandgap edge, which is advantageous for optical applications. A layered oxysulfide, LaCuOS, was proposed to be a promising material for optoelectronic devices.

Effective Application of Magnetic Material Based on Metamaterial Absorber

2013 ◽  
Vol 774-776 ◽  
pp. 907-912
Author(s):  
Hui Bin Zhang ◽  
Li Wei Deng ◽  
Nan Zhang ◽  
Pei Heng Zhou ◽  
Jian Liang Xie ◽  
...  
Keyword(s):  
Magnetic Material ◽  
Design Method ◽  
Copper Wire ◽  
Wire Array ◽  
Magnetic Loss ◽  
Peak Position ◽  
Metamaterial Absorber ◽  
Absorption Peak ◽  
Perfect Absorption ◽  
Effective Application

We simulate, fabricate and measure a microwave absorber by introducing metamaterial design method to magnetic material. The proposed absorber is composed of periodic copper wire array, magnetic material coated on copper wires, a foam substrate and a bottom metal plane. The results show a nearly perfect absorption peak around 8.7GHz (simulated) and 7.6GHz (measured). Even though the electric and magnetic field distribution indicate that the absorption is a typical metamaterial absorption, the power loss is neither Ohmic nor dielectric loss but magnetic loss, which is different from typical metamaterial absorber. The skillful introduction of the magnetic loss improves the absorption performance, including the absorption bandwidth and intensity. The designed absorber shows an effective application of the magnetic material, which is only 1/60000 volume proportion of the total absorber. Dependences of the absorption on frequency and the coating volume of the magnetic material manifest that the coated magnetic material can adjust the absorption peak position and intensity. The absorber can be an attractive candidate of electromagnetic wave absorber.

LITHIUM CHLORIDE CATALYZED DECARBOXYLATION OF OXALACETIC ACID IN ETHANOL

1964 ◽  
Vol 42 (12) ◽  
pp. 2806-2810 ◽  
Author(s):  
G. W. Kosicki ◽  
S. N. Lipovac ◽  
R. G. Annett
Keyword(s):  
Hydrogen Chloride ◽  
Lithium Chloride ◽  
Pyruvic Acid ◽  
Metal Salt ◽  
Enol Form ◽  
Absorption Peak ◽  
Oxalacetic Acid ◽  
Monovalent Metal

The monovalent metal salt lithium chloride promotes the decarboxylation of oxalacetic acid in ethanol. The absorption peak which appears at 230 mμ during the reaction is interpreted to be the enol form of pyruvic acid. Hydrogen chloride has a similar effect on the decarboxylation.

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