Native Defect Characterization in ZnGeP2

1999 ◽  
Vol 607 ◽  
Author(s):  
A. Hoffmann ◽  
H. Born ◽  
A. Näser ◽  
W. Gehlhoff ◽  
J. Maffetone ◽  
...  
Keyword(s):  
Energy Range ◽  
Infrared Emission ◽  
Peak Position ◽  
Metastable Equilibrium ◽  
Chalcopyrite Structure ◽  
Luminescence Spectra ◽  
Broad Emission Band ◽  
Cation Sublattice ◽  
Broad Emission ◽  
Donor Acceptor

AbstractElectron paramagnetic resonance (EPR) as well as time-resolved and time-integrated photoluminescence (PL) are used to characterize the defect centers in ZnGeP2 bulk crystals. The samples, as-grown, electron-irradiated and annealed, reveal a strong intensity dependence of the VZn-correlated EPR-transitions. Photo-EPR experiments show that this intensity behavior is mainly caused by a recharging of the VZn centers owing to the preparation induced shift of the Fermi-level. The luminescence spectra show a broad infrared emission with peak position at 1.23 eV that exhibits features of classical donor-acceptor recombination. The hyperbolic decay characteristics, investigated in energy range from 1.2 eV up to 1.5eV, suggest that this broad emission band is related to one energetic recombination center. This recombination is interpreted to be between donor-acceptor states related to residual disorder on the cation sublattice that is retained in metastable equilibrium during the formation of the chalcopyrite structure. The emission decay behavior in the energy range from 1.2 eV up to 1.6 eV is characterized by two hyperbolic time constants, and explained as the super-composition of the decays from the broad emission center peaked at 1.2 eV and an additional donor-acceptor recombination centers at 1.4 eV.

scholarly journals Defect Characterization in ZnGeP2 by Time -Resolved Photoluminescence

1996 ◽  
Vol 450 ◽  
Author(s):  
N. Dietz ◽  
W. Busse ◽  
H. E. Gumlich ◽  
W. Ruderman ◽  
I. Tsveybak ◽  
...  
Keyword(s):  
Energy Range ◽  
Infrared Emission ◽  
Luminescence Spectra ◽  
Broad Emission Band ◽  
Wide Energy Range ◽  
Time Resolved ◽  
Broad Emission ◽  
Donor Acceptor ◽  
Donor States ◽  
Time Resolved Photoluminescence

AbstractSteady state and time-resolved photoluminescence (PL) investigations on ZnGeP2 crystals grown from the vapor phase by high pressure physical vapor transport (HPVT) and from the melt by gradient freezing (GF) are reported. The luminescence spectra reveal a broad infrared emission with peak position at 1.2 eV that exhibits features of classical donor-acceptor recombination. The hyperbolic decay characteristic over a wide energy range, investigated from 1.2 eV up to 1.5eV, suggest that this broad emission band is related to one energetic recombination center. Higher energetic luminescence structures at 1.6eV and 1.7eV were revealed after annealing of ZnGeP2 crystals in vacuum for a longer period of time. The emission decay behavior in this energy range is characterized by two hyperbolic time constants, viewed as the supercomposition of the decay from the broad emission center peaked at 1.2eV and additional donor-acceptor recombination emissions at 1.6eV and 1.7eV, respectively. ZnGeP2 crystals grown under Ge-deficient conditions by HPVT show an additional emission structure at 1.8 eV with sharp emission fine structures at 1.778 eV related to the presence of additional donor states.

A Luminescent Probe Study of Water/Acetonitrile Mixtures

1979 ◽  
Vol 32 (2) ◽  
pp. 271 ◽  
Author(s):  
AJ Easteal
Keyword(s):  
Salicylic Acid ◽  
Luminescence Band ◽  
Composition Dependence ◽  
Water Structure ◽  
Luminescence Spectra ◽  
Broad Emission Band ◽  
Luminescent Probe ◽  
Broad Emission ◽  
Alcohol Mixtures ◽  
Water Alcohol

Luminescence spectra for 1.0 × 10-2 mol dm-3 solutions of salicylic acid in water, acetonitrile and water/acetonitrile mixtures have been determined. In the wavelength range 300-600 nm, all spectra showed a single broad emission band. The variations of the wavelength of maximum luminescence intensity (λmax) and luminescence band half-width (Δ�) with solvent composition are similar to the composition dependence of these parameters observed previously for solutions of salicylic acid in water/alcohol mixtures. The invariance of Δ� with acetonitrile content up to approximately 15 mole% supports earlier conclusions that up to c. 15 mole% acetonitrile is accommodated within cavities in the water structure. The rapid increase in near 15 mole% acetonitrile provides further evidence for a progressive destruction of the water structure as the acetonitrile content is increased beyond c. 15 mole%.

scholarly journals Exploring the link between C IV outflow kinematics and sublimation-temperature dust in quasars

2020 ◽  
Author(s):  
Matthew J Temple ◽  
Manda Banerji ◽  
Paul C Hewett ◽  
Amy L Rankine ◽  
Gordon T Richards
Keyword(s):  
Emission Line ◽  
High Frequency ◽  
Infrared Emission ◽  
Black Hole Mass ◽  
Sublimation Temperature ◽  
Continuum Source ◽  
Broad Emission ◽  
Line Region ◽  
Using Data

Abstract Using data from SDSS, UKIDSS and WISE, we investigate the properties of the high-frequency cutoff to the infrared emission in ≃5000 carefully selected luminous (Lbol ∼ 1047) type 1 quasars. The strength of ≃2 μm emission, corresponding to emission from the hottest ($T>1200\rm \, K$) dust in the sublimation zone surrounding the central continuum source, is observed to correlate with the blueshift of the C iv λ1550 emission line. We therefore find that objects with stronger signatures of nuclear outflows tend to have a larger covering fraction of sublimation-temperature dust. When controlling for the observed outflow strength, the hot dust covering fraction does not vary significantly across our sample as a function of luminosity, black hole mass or Eddington fraction. The correlation between the hot dust and the C iv line blueshifts, together with the lack of correlation between the hot dust and other parameters, therefore provides evidence of a link between the properties of the broad emission line region and the infrared-emitting dusty regions in quasars.

Excitation Power Dependence of Photoluminescence in CIB and FIB Implanted Superlattices

1991 ◽  
Vol 240 ◽  
Author(s):  
A. G. Choo ◽  
H. E. Jackson ◽  
P. Chen ◽  
A. J. Steckl ◽  
V. Gupta ◽  
...  
Keyword(s):  
Focused Ion Beam ◽  
Ion Beam ◽  
Peak Position ◽  
Excitation Power ◽  
Excitation Intensity ◽  
Power Dependence ◽  
Photoluminescence Spectra ◽  
Multiple Scan ◽  
Donor Acceptor ◽  
Low Temperature Photoluminescence

ABSTRACTLow temperature photoluminescence spectra have been used to characterize conventional ion beam (CIB) and focused ion beam (FIB) implanted superlattices. The excitation dependence of the single scan FIB is found to be significantly different from CIB and multiple scan FIB implantations which are similar. The peak position of the donor-acceptor transition is observed to change to higher energies significantly slower with excitation intensity for the single scan FIB case when compared to the multiple scan FIB and CIB cases. Simple models to describe these effects are briefly discussed.

Lu3(Al,Si)5(O,N)12:Ce3+ phosphors with broad emission band and high thermal stability for white LEDs

2015 ◽  
Vol 158 ◽  
pp. 322-327 ◽  
Author(s):  
Jiaqing Liu ◽  
Xiaojun Wang ◽  
Tongtong Xuan ◽  
Chunbo Wang ◽  
Huili Li ◽  
...  
Keyword(s):  
Thermal Stability ◽  
Emission Band ◽  
High Thermal Stability ◽  
Broad Emission Band ◽  
White Leds ◽  
Broad Emission

scholarly journals A Novel DR/NIR T-Shaped AIEgen: Synthesis and X-Ray Crystal Structure Study

Crystals ◽  
2020 ◽  
Vol 10 (4) ◽  
pp. 269 ◽  
Author(s):  
Rosita Diana ◽  
Ugo Caruso ◽  
Luigi Di Costanzo ◽  
Gelsomina Bakayoko ◽  
Barbara Panunzi
Keyword(s):  
Crystal Structure ◽  
Near Infrared ◽  
Condensation Product ◽  
Infrared Emission ◽  
Structure Study ◽  
X Ray ◽  
Hydrogen Bond Interactions ◽  
Main Plane ◽  
Donor Acceptor ◽  
Intramolecular Hydrogen

We developed a new benzodifuran derivative as the condensation product between 2,6-diamino-4-(4-nitrophenyl)benzo[1,2-b:4,5-b’]difuran-3,7-dicarboxylate and 3-hydroxy-2-naphthaldehyde. The intramolecular hydrogen-bond interactions in the terminal half-salen moieties produce a sterically encumbered highly conjugated main plane and a D-A-D (donor-acceptor-donor) T-shaped structure. The novel AIEgen (aggregation-induced enhanced emission generator) fulfils the requirement of RIR (restriction of intramolecular rotation) molecules. DR/NIR (deep red/near infrared) emission was recorded in solution and in the solid state, with a noteworthy photoluminescence quantum yield recorded on the neat crystals which undergo some mechanochromism. The crystal structure study of the probe from data collected at a synchrotron X-ray source shows a main aromatic plane π-stacked in a columnar arrangement.

Absorption, Fluorescence and Emission Anisotropy Spectra of 4-Cyano-N,N-dimethylaniline in Different Media and at Different Temperatures

1997 ◽  
Vol 52 (5) ◽  
pp. 409-414
Author(s):  
A. Kawski ◽  
G. Piszczek
Keyword(s):  
Emission Band ◽  
Effect Of Temperature ◽  
Broad Emission Band ◽  
Fixed Temperature ◽  
Emission Anisotropy ◽  
Paraffin Oil ◽  
Broad Emission ◽  
Negative Emission ◽  
Different Temperatures ◽  
Anisotropy Spectra

Abstract The effect of temperature on fluorescence and emission anisotropy spectra of 4-cyano-N,N-dimethylaniline (CDMA) was investigated in viscous (glycerol and paraffin oil) and rigid (polyvinyl alcohol) PVA and polyvinyl chloride) PVC) media. A strong effect of temperature on the intensity of a and b emission bands was observed. It was also found that the emission anisotropy, r, does not vary in the longwave emission band a at a fixed temperature but decreases in the emission band b together with the decreasing wavelength. The latter effect is due to the fact that the transition moment in this band is perpendicular to the long axis of the CDMA molecule. For CDMA in paraffin oil, a normal b band with negative emission anisotropy only occurs. In all other media used, the emission anisotropy has lower values, approaching zero, which results from the considerable covering of band b with a broad emission band a.

Two Ce3+ centers induced broadband emission in Y3Si6N11:Ce3+ yellow phosphor

2018 ◽  
Vol 47 (46) ◽  
pp. 16723-16728 ◽  
Author(s):  
Dashuai Sun ◽  
Liangliang Zhang ◽  
Zhendong Hao ◽  
Xia Zhang ◽  
Guo-Hui Pan ◽  
...  
Keyword(s):  
Emission Band ◽  
Emission Center ◽  
Broad Emission Band ◽  
Yellow Phosphor ◽  
Broadband Emission ◽  
Broad Emission

A Ce2 emission center was found in Y3Si6N11:Ce3+ and the broad emission band was successfully decomposed into Ce1 and Ce2.

A Series of 2D and 3D Novel Lanthanide Complexes Constructed from Squarate C4O42–: Syntheses, Structures, Magnetic Properties, and Near-infrared Emission Properties

2011 ◽  
Vol 64 (10) ◽  
pp. 1373 ◽  
Author(s):  
Li Wang ◽  
Wen Gu ◽  
Xiu-Jun Deng ◽  
Ling-Fei Zeng ◽  
Sheng-Yun Liao ◽  
...  
Keyword(s):  
Magnetic Properties ◽  
Near Infrared ◽  
Variable Temperature ◽  
Infrared Emission ◽  
Luminescence Spectra ◽  
Coordination Modes ◽  
Metal Precursors ◽  
Trivalent Lanthanide ◽  
Lanthanide Metal ◽  
2D And 3D

The solvothermal combination of trivalent lanthanide metal precursors with a squarate ligand (H2C4O4, 3,4-dihydroxy-3-cyclobutene-1,2-dione) has afforded the preparation of a family of eight new coordination polymers, [Ln2(C4O4)3(H2O)4] (Ln = La–Nd, Ho) (1–5), [Ln2(C4O4)3(H2O)8] (Ln = Er, Dy) (6, 7), and Tb2(C4O4)2(C2O4)(H2O)4 (8). Structural analysis reveals that the squarate ligand displays versatile coordination modes to generate novel 2D and 3D frameworks. Three new coordination modes, a bidentate/monodentate μ3 and two bidentate/monodentate μ4 coordination modes, are first reported. In addition, the variable-temperature magnetic properties of the Pr, Nd, Ho, Dy, and Tb complexes, the solid-state near-infrared luminescence spectra of the Pr, Nd, Ho, and Er complexes, and their thermogravimetric analyses are discussed.

Synthesis and Luminescent Properties of Violet-Ultraviolet Long Afterglow Phosphors

2010 ◽  
Vol 663-665 ◽  
pp. 170-176
Author(s):  
Hao Yi Wu ◽  
Yi Hua Hu ◽  
Yin Hai Wang ◽  
Chu Jun Fu ◽  
Feng Wen Kang ◽  
...  
Keyword(s):  
Solid State ◽  
Oxygen Vacancies ◽  
Trap Depth ◽  
Luminescent Properties ◽  
Solid State Reaction Method ◽  
Broad Emission Band ◽  
Suitable Model ◽  
Reaction Method ◽  
Long Afterglow ◽  
Broad Emission

The M1.99MgSi2O7: Ce3+0.01 (M: Ba, Sr, Ca) phosphors were prepared by the solid-state reaction method. All the samples emit the violet-ultraviolet light with a broad emission band from about 330 nm to 500 nm. All the phosphors samples show a long afterglow. The strongest afterglow intensity and the longest decay duration of the afterglow come from the Ca1.99MgSi2O7: Ce3+0.01 sample. It is attributed to the suitable trap depth and the high trap concentration of this sample. The traps of these phosphors are induced by the lattice defects. A suitable model involving the cation vacancies and the oxygen vacancies, which act as the hole traps and the electron traps respectively, is proposed.

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