The ppb-level formaldehyde detection with UV excitation for yolk-shell MOF-derived ZnO at room temperature

2021 ◽  
pp. 131294
Author(s):  
Wanyi ling ◽  
Dachuan zhu ◽  
Yong pu ◽  
Haokun li
Keyword(s):  
Room Temperature ◽  
Uv Excitation

scholarly journals Optical Investigation of Eu3+ Doped Bi12GeO20 (BGO) Crystals

Crystals ◽  
2020 ◽  
Vol 10 (4) ◽  
pp. 285 ◽  
Author(s):  
M. Kowalczyk ◽  
T.F. Ramazanova ◽  
V.D. Grigoryeva ◽  
V.N. Shlegel ◽  
M. Kaczkan ◽  
...  
Keyword(s):  
Energy Transfer ◽  
Room Temperature ◽  
Transition Probabilities ◽  
Spectroscopic Properties ◽  
Electric Dipole Transition ◽  
Optical Investigation ◽  
Bulk Crystals ◽  
Czochralski Technique ◽  
Uv Excitation ◽  
Transfer Mechanisms

The spectroscopic properties of Eu3+ doped Bi12GeO20 (BGO) sillenite bulk crystals that were grown by the low-thermal-gradient Czochralski technique (LTG Cz) were investigated. The absorption spectra and the emission properties have been measured at room temperature (300 K) and at 10 K. Luminescence was observed both due to the direct Eu3+ ion excitation, as well as under UV excitation due to the energy transfer between Bi3+ and Eu3+ ions. Bi3+ → Eu3+ energy transfer mechanisms in Eu3+:BGO doped host were investigated. The Ωλ parameters, as well as radiative lifetimes, were calculated based upon the Judd-Ofelt formalism. The branching ratios and electric dipole transition probabilities were also determined, based upon the obtained experimental results. Luminescence has been observed from the 5D0,1,2 levels of Eu3+, with emissions from the 5D0 level being the strongest. The strongest observed luminescence band corresponds to the 5D0 → 7F0 transition at 578.7 nm. Reasons for the strong presence of the theoretically forbidden 5D0 → 7F0 emission were investigated.

ZnS:Mn2+ Quantum Dots as Efficient Photocatalyst for Organic Dye Decolorization

2018 ◽  
Vol 386 ◽  
pp. 207-213
Author(s):  
Ksenia A. Sergeeva ◽  
Alexander A. Sergeev ◽  
Yulia V. Kuznetsova ◽  
Sergey S. Voznesenskiy
Keyword(s):  
Methylene Blue ◽  
Quantum Dots ◽  
Photocatalytic Activity ◽  
Room Temperature ◽  
Dye Decolorization ◽  
Organic Dye ◽  
Intrinsic Defect ◽  
Zinc Blende ◽  
Decolorization Efficiency ◽  
Uv Excitation

Fluorescent zinc blende structured pure and Mn2+ doped ZnS quantum dots were prepared by simple aqueous based technique at room temperature. Under UV-excitation the quantum dots show photoluminescence bands at 2.1 and 3.0 eV corresponded to Mn2+ and ZnS intrinsic defect emission, respectively. The photocatalytic activity was tested for the photodegradation of methylene blue in aqueous solution. The influence of the Mn2+ concentration on the dye decolorization efficiency was studied. The highest photocatalytic degradation rate of methylene blue was obtained for ZnS quantum dots in glutathione shell doped with 0.5 at.% of Mn2+. The mechanisms of photoluminescence and photocatalytic activity were discussed.

Ultraviolet Photoluminescence Imaging of Stacking Fault Contraction in 4H-SiC Epitaxial Layers

2012 ◽  
Vol 717-720 ◽  
pp. 391-394 ◽  
Author(s):  
Nadeemullah A. Mahadik ◽  
Robert E. Stahlbush ◽  
Joshua D. Caldwell ◽  
Karl D. Hobart
Keyword(s):  
Low Power ◽  
Point Defects ◽  
Room Temperature ◽  
Stacking Fault ◽  
Epitaxial Layers ◽  
First Time ◽  
Uv Excitation ◽  
Line Direction

Shockley stacking fault (SSF) contraction in 4H-SiC was investigated, in-situ, under varying temperature and ultraviolet (UV) intensity. Contraction of single SSFs at room temperature was observed for the first time under low power UV excitation of 0.04 W/cm2. At temperatures above 150 °C, complete SSF contraction occurred for UV power at 0.2 W/cm2. In contrast to expansion, SSF contraction occurred in discrete jumps between pinning sites along existing C-core partials. Luminescence from the pinning sites suggest they may be local concentrations of point defects. Additionally, a change in the line direction of the Si-core partials by ~25o off the direction was observed.

Intense RT Visible Photoluminescence from Anodized Amorphous and Nanocrystalline Silicon Films

1992 ◽  
Vol 283 ◽  
Author(s):  
E. Bustarret ◽  
J. C. Bruyere ◽  
F. Muller ◽  
M. Ligeon
Keyword(s):  
Porous Silicon ◽  
Room Temperature ◽  
Nanocrystalline Silicon ◽  
Current Debate ◽  
X Ray ◽  
Boron Doped ◽  
Intense Luminescence ◽  
Conductive Substrates ◽  
Uv Excitation ◽  
Room Temperature Luminescence

ABSTRACTHeavily Boron-doped micrometer-thick amorphous (a-Si:B:H) or nanocrystalline (nc-Si) silicon layers have been deposited on a variety of conductive substrates by the 50 KHz PECVD of SiH4 / B2H6 / H2 mixtures at 320°C. These films have been partially electro-oxidized in a HF solution and then anodically oxidized in water in a manner similar to that yielding luminescent porous monocrystalline silicon layers (PcSL). Although the anodized films are x-ray amorphous, they yield intense luminescence properties at room temperature very similar to those of anodically oxidized PcSL with a similar vibrational spectrum. In both anodically oxidized materials, aging is shown to improve the external quantum efficiency. In amorphous anodized layers, optical microscopy under UV excitation showed strongly luminescent strain-related heterogeneities (20 μ,m in diameter) connected by non luminescent channels. The incidence of our results on the current debate about the origin of visible room-temperature luminescence in porous silicon and Si:O:H systems is discussed.

Spectroscopic Properties of Cubic SiC on Si

2002 ◽  
Vol 742 ◽  
Author(s):  
Z. C. Feng ◽  
D. N. Talwar ◽  
I. Ferguson
Keyword(s):  
Room Temperature ◽  
Vapour Deposition ◽  
Function Theory ◽  
Chemical Vapour ◽  
Spectroscopic Properties ◽  
Spectroscopic Studies ◽  
Room Temperature Photoluminescence ◽  
Raman Modes ◽  
Indirect Band Gap ◽  
Uv Excitation

ABSTRACTSpectroscopic studies are reported for cubic SiC grown on Si by chemical vapour deposition (CVD) manufacture technique. The UV excitation room temperature photoluminescence (PL)-Raman spectra exhibited 2.3 eV luminescence line due to RT recombination over the SiC indirect band gap. In addition to the optical phonons from cubic SiC we observed new Raman modes near 620 and 833 cm-1. A comprehensive analysis of the dynamical properties of defects using Green's function theory has suggested isolated impurity vibrations to be the possible origin for the additional phonons observed by Raman spectroscopy.

Photoluminescence of Eu3+ Ions in Lu3(Ga,In)5O12:Eu3+ Films Grown by LPE Method

2015 ◽  
Vol 230 ◽  
pp. 166-171
Author(s):  
Andriy Luchechko ◽  
I.I. Syvorotka ◽  
Yaroslav Zakharko ◽  
Igor M. Syvorotka
Keyword(s):  
Room Temperature ◽  
Emission Spectra ◽  
Epitaxial Films ◽  
Decay Kinetics ◽  
Exponential Behavior ◽  
Efficient Energy Transfer ◽  
Kinetics Of ◽  
Uv Excitation ◽  
The Eu ◽  
Luminescence Decay Kinetics

High quality thin epitaxial films of Lu3(Ga,In)5O12:Eu3+ were grown by liquid phase epitaxy (LPE) method from Bi2O3-based flux. Excitation and emission spectra as well as luminescence decay kinetics of Lu3(Ga,In)5O12:Eu3+ epitaxial films were studied under UV excitation. The photoluminescence spectra of Eu3+ ions in Lu3(Ga,In)5O12:Eu3+ are characteristic to the f→f transition in the Eu3+ ions that occupied dodecahedral sites in the garnet structure. The efficient energy transfer between Bi3+→Eu3+ is observed at the excitation of Lu3(Ga,In)5O12:Eu3+ films in Bi3+ excitation band with maximum at 288 nm. The Eu3+ decay curves of all investigated films show non-single exponential behavior at room temperature.

Nondestructive Analysis of Stacking Faults in 4H-SiC Bulk Wafers by Room-Temperature Photoluminescence Mapping under Deep UV Excitation

2007 ◽  
Vol 556-557 ◽  
pp. 275-278 ◽  
Author(s):  
Norihiro Hoshino ◽  
Michio Tajima ◽  
Toshihiko Hayashi ◽  
Taro Nishiguchi ◽  
Hiroyuki Kinoshita ◽  
...  
Keyword(s):  
Room Temperature ◽  
Stacking Faults ◽  
Surface Region ◽  
Nondestructive Analysis ◽  
Room Temperature Photoluminescence ◽  
Basal Plane Dislocation ◽  
Pl Mapping ◽  
Light Excitation ◽  
Shaped Pattern ◽  
Uv Excitation

The advantage of room-temperature photoluminescence (PL) mapping was demonstrated for nondestructive detection of stacking faults (SFs) in off-oriented 4H-SiC epitaxial and bulk wafers. In mapping of the SF-related emission at 2.9 eV on the wafers, the SFs in the surface region appeared as a bar-shaped pattern with the long side perpendicular to the off-cut direction. The use of 266 nm light excitation is essential to detect the SF pattern in the bulk wafers because of its shallow penetration depth. The dark lines crossing the bar-shaped patterns in the epitaxial wafers are ascribable to the basal plane dislocation located close to the SF-planes.

UV excitation NO2 gas sensor sensitized by ZnO quantum dots at room temperature

2018 ◽  
Vol 259 ◽  
pp. 526-531 ◽  
Author(s):  
Tong Wu ◽  
Zhenbo Wang ◽  
Menghan Tian ◽  
Jiayu Miao ◽  
Haixue Zhang ◽  
...  
Keyword(s):  
Quantum Dots ◽  
Gas Sensor ◽  
Room Temperature ◽  
No2 Gas Sensor ◽  
Zno Quantum Dots ◽  
Uv Excitation
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