Room-temperature near-ultraviolet electroluminescence from a linear silicon chain

1997 ◽  
Vol 71 (23) ◽  
pp. 3326-3328 ◽  
Author(s):  
Chien-Hua Yuan ◽  
Satoshi Hoshino ◽  
Seiji Toyoda ◽  
Hiroyuki Suzuki ◽  
Michiya Fujiki ◽  
...  
Keyword(s):  
Room Temperature ◽  
Near Ultraviolet

Notizen:Phosphorescence Decay in Thallium-Doped Ammonium Chloride

1978 ◽  
Vol 33 (10) ◽  
pp. 1241-1242 ◽  
Author(s):  
S. Chaudhari ◽  
T. R. Joshi ◽  
R. V. Joshi
Keyword(s):  
Aqueous Solution ◽  
Ammonium Chloride ◽  
Mechanical Treatment ◽  
Room Temperature ◽  
Host Lattice ◽  
Luminescence Decay ◽  
Decay Rates ◽  
Negative Ion ◽  
Ultraviolet Emission ◽  
Near Ultraviolet

Abstract The phosphorescence decay rates of thallium-doped ammonium chloride (NH4Cl:Tl) phosphors, prepared by crystallization from aqueous solution, have been studied at room temperature for near-ultraviolet emission. The effects of impurity concentration as well as thermal and/or mechanical treatment on the decay rates have been examined. Phosphorescence centres consisting of a Tl+ion and a nearby negative ion vacancy are suggested to be responsible for the observed luminescence decay. The changes in the decay characteristics after pretreatments are explained on the basis of the location of the centres in normal and distorted regions of the host lattice.

Highly Efficient and Thermally Stable Eu2+-Doped Ca9Nd(PO4)7 Phosphor for Near-Ultraviolet White-Emission LED Applications

2021 ◽  
Vol 21 (12) ◽  
pp. 5859-5866
Author(s):  
Jian Zhou ◽  
Si-Li Ren
Keyword(s):  
Room Temperature ◽  
Green Emission ◽  
Color Temperature ◽  
Multipole Interaction ◽  
Interaction Radius ◽  
Promising Alternative ◽  
Quenching Effect ◽  
Near Ultraviolet ◽  
Great Performance ◽  
Concentration Quenching Effect

Various Eu2+-based Ca9Nd(PO4)7 (CNP:xEu2+, with different x values) materials are prepared via facile solid-state reaction. Their crystal structures are investigated in detail by means of the Rietveld refinement. The structure of CNP:Eu2+ with a trigonal lattice is analogous to that of β-Ca3(PO4)2. Therefore, Eu2+ ions tend to incorporate calcium sites in the host. All the obtained samples can be excited using near ultraviolet (nUV) light to present blue-green emission. An optimal dopant concentration is verified at x = 0.8 with a large critical interaction radius (11.21 Å). The mechanism of the concentration quenching effect is assigned to the multipole-multipole interaction. CNP:xEu2+ possesses a short decay lifetime of ∼60 μs and can endure severe working conditions thanks to its great thermal stability. The relative photoluminescence (PL) intensity of CNP:0.8Eu2+ can retain 84.75% of the pristine intensity measured at room temperature, and the relative intensity remains as high as 69.97% at 423 K. The CNP:Eu2+ phosphors also show great performance in the WLED demonstration. The correlated color temperature (CCT) of the prototype device is 3404 K, with an extremely high Ra (97.6). Therefore, CNP:xEu2+ could be regarded as a promising alternative to blue green phosphors in nUV chip-based WLED applications.

The Near-ultraviolet Absorption Spectrum of Diimide in Liquid Ammonia and its Decomposition between −65 and −38 °C

1974 ◽  
Vol 52 (13) ◽  
pp. 2513-2515 ◽  
Author(s):  
R. A. Back ◽  
C. Willis
Keyword(s):  
Absorption Spectrum ◽  
Gas Phase ◽  
Room Temperature ◽  
Liquid Ammonia ◽  
Vibrational Structure ◽  
Ultraviolet Absorption ◽  
Ultraviolet Absorption Spectrum ◽  
First Order ◽  
Rapid Decomposition ◽  
Near Ultraviolet

The near-ultraviolet absorption spectrum of diimide in liquid ammonia at −50 °C is shifted about 500 Å to the red compared with the gas-phase spectrum, with λmax = 4000 Å. The spectrum is also broadened and the vibrational structure largely obscured. It is suggested that hydrogen bonding is responsible for these changes.Diimide is much more stable in liquid ammonia between −65 and −38 °C than in the gas phase at room temperature. A first-order decay is observed with Arrhenius parameters of A = 1.9 × 103 s−1 and E = 6.6 kcal/mol; this is always preceded by a more rapid, higher-order initial decay which may be related to the rapid decomposition observed during vaporization.

Strong near-ultraviolet and blue emissions at room temperature from two-step grown In-rich InGaN/GaN multiple quantum wells

2006 ◽  
Vol 1 (1) ◽  
pp. 53 ◽  
Author(s):  
S.-Y. Kwon ◽  
S.-I. Baik ◽  
H.J. Kim ◽  
P. Moon ◽  
Y.-W. Kim ◽  
...  
Keyword(s):  
Quantum Wells ◽  
Room Temperature ◽  
Multiple Quantum Wells ◽  
Multiple Quantum ◽  
Near Ultraviolet

Cerium Containing Chalcogenides with Chromatic Properties

1998 ◽  
Vol 548 ◽  
Author(s):  
G. Gauthier ◽  
S. Jobic ◽  
P. Macaujdiere ◽  
R. Brec
Keyword(s):  
Electronic Transition ◽  
Room Temperature ◽  
Inductive Effect ◽  
Transition Energy ◽  
Ionic Character ◽  
Blue Fluorescence ◽  
Energy Increase ◽  
Near Ultraviolet ◽  
Visible Spectra ◽  
Chromatic Properties

ABSTRACTλ–Ce2S3, like many other cerium containing chalcogenides, presents a strong absorption in the visible spectra in relation with the CeIII-4fl → CeIII-5d1 electronic transition taking place at around 1.9 eV. This transition energy, that induces a red hue for the phase, can be increased by changing the nature of the Ce-S bonding, in particular through an enhancement of its ionicity. This can be made by inserting/substituting some alkali metal ions in the structure of λ-Ce2S3. The sodium-doped λ-Na3/8Ce15/2S3 phase for instance undergoes a CeIII-4f1 → Cemi-5d1 transition energy increase of 0.12 eV. This shift is sufficient to modify substantially the pigment properties of the material and it has been mainly related to the narrowing of the electronic bands. In CePS4, Ce2SiS5, Ce4Si3S12and Ce6Si4S17, strong covalent bondings enhance the ionic Ce-S bond through inductive effect, leading to a CeIII-4f1 → CeIII-5d1 electronic transition in the blue (Eg - 2.5 eV) hence the yellow hue of these materials. Within the Ce-Si-S family, small differences may be attributed to difference in the [CeSx] and [SiS4] polyhedra bonding. The Ce3(TS4 )2X family (X = Cl, Br, I, T = Si, Ge) does not show pigment properties because of the Ce-X bond inducing a more Ce-S ionic character (in particular when X = Br, I) and thus a higher gap that is found in the near ultraviolet. On the other hand, the phases present an important room temperature blue fluorescence.

Facile route to tin oxide containing mesoporous silica composites with room-temperature photoluminescence

2006 ◽  
Vol 21 (3) ◽  
pp. 655-663 ◽  
Author(s):  
Zhicheng Liu ◽  
Hangrong Chen ◽  
Weiming Huang ◽  
Jinlou Gu ◽  
Wenbo Bu ◽  
...  
Keyword(s):  
Mesoporous Silica ◽  
Tin Oxide ◽  
Room Temperature ◽  
Uv Light ◽  
Treatment Method ◽  
Preparation Temperature ◽  
Strong Emission ◽  
Room Temperature Photoluminescence ◽  
Near Ultraviolet ◽  
Facile Route

In this paper, we report a facile route, the tin vapor treatment method, to prepare tin oxide containing mesoporous silica composites (TOMS), which display room-temperature photoluminescence (RT-PL). Among them, TOMS-1 and TOMS-2 were synthesized from mesoporous silica SBA-15 and KIT-6, respectively. They are composed of amorphous SiO2 and tin oxide species and they display strong emission near ultraviolet (UV) when excited by UV light. By increasing the preparation temperature, their Sn content can be increased and subsequently their photoluminescence (PL) intensities can be greatly enhanced. Besides, their PL properties are revealed to be closely related to 2-fold-coordinated tin oxygen-deficient centers.

Optically-Induced, Room-Temperature Oxidation of Gallium Arsenide

1986 ◽  
Vol 75 ◽  
Author(s):  
Chien-Fan Yu ◽  
Michael T. Schmidt ◽  
Dragan V. Podlesnik ◽  
Richard M. Osgood
Keyword(s):  
Growth Rate ◽  
Gallium Arsenide ◽  
Laser Radiation ◽  
Visible Light ◽  
Room Temperature ◽  
Water Molecules ◽  
Temperature Oxidation ◽  
Near Ultraviolet ◽  
Deep Ultraviolet ◽  
Optically Induced

AbstractRoom-temperature, optically-induced oxidation of the gallium arsenide surface has been studied with laser radiation of different wavelengths. It was found that deep-ultraviolet light is much more effective in enhancing oxidation than near-ultraviolet or visible light. The growth rate of the oxide was also found to be drastically increased by the presence of chemisorbed water molecules on the surface.

Morphology evolution of Eu3+-activated NaTbF4 nanorods: a highly-efficient near-ultraviolet light-triggered red-emitting platform towards application in white light-emitting diodes

2019 ◽  
Vol 7 (35) ◽  
pp. 10802-10809 ◽  
Author(s):  
Peng Du ◽  
Weiguang Ran ◽  
Weiping Li ◽  
Laihui Luo ◽  
Xiaoyong Huang
Keyword(s):  
Ultraviolet Light ◽  
White Light ◽  
Room Temperature ◽  
Light Emitting Diodes ◽  
Morphology Evolution ◽  
Light Emitting ◽  
Highly Efficient ◽  
Near Ultraviolet ◽  
White Light Emitting Diodes

A series of NaTbF4 and Eu3+-activated NaTbF4 nanorods with high luminescent efficiency were designed by using an ingenious reaction technique at room temperature.

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