scholarly journals Excitonic Bands in the Optical Absorption Spectra of (Bu4N)CuBr2, (Et4N)2Cu2Br4, (Pr4N)2Cu4Br6, (Bu4N)2Cu2I4, (Me4N)Cu2I3, (Pr4N)4Ag4I8, (Me4N)Ag2I3, (Et4N)Ag2Br3, and Similar Compounds

1999 ◽  
Vol 54 (1) ◽  
pp. 109-112 ◽  
Author(s):  
G. C. Papavassilioua ◽  
G. A. Mousdis ◽  
A. Terzis ◽  
C. P. Raptopoulou
Keyword(s):  
Optical Absorption ◽  
Spectral Region ◽  
Quantum Confinement ◽  
Optical Absorption Spectra ◽  
Bulk Materials ◽  
Trivalent Metal ◽  
Absorption Bands ◽  
Bivalent Metal ◽  
Halide Complexes ◽  
Low Dimensional

The title compounds (natural low-dimensional semiconductor systems) exhibit strong excitonic optical absorption bands in the UV spectral region, because of the quantum confinement of excitons, as in the cases of bivalent-metal and trivalent-metal halide complexes. The excitonic bands are shifted to longer wavelengths, approaching those of the corresponding bulk materials, as the anion-size or the anion-dimensionality increases.

Excitonic Bands in the Optical Absorption Spectra of A3MX6 and A3M2X9 (A = MeNH3, Me2NH2, Me3NH, Me4N; M = Bi, Sb; X = Cl, Br, I)

1994 ◽  
Vol 49 (6) ◽  
pp. 849-851 ◽  
Author(s):  
G. C. Papavassiliou ◽  
I. B. Koutselas
Keyword(s):  
Optical Absorption ◽  
Absorption Spectra ◽  
Spectral Region ◽  
Visible Spectral Region ◽  
Optical Absorption Spectra ◽  
Absorption Bands ◽  
Uv Visible ◽  
Low Dimensional

The title compounds (natural low-dimensional semiconductors) show strong excitonic optical absorption bands in the UV-visible spectral region, because of the dielectric confinement of excitons. as in the cases of other similar systems based on PbX2-4, SnX2-4. PtI - X - PtIV-X , Cdx,Sy-clusters etc

Quantum Confinement Effects in Calcium Sulfide: The Role of Indirect Transitions in the Red Shift of the Band Edge in Semiconductor Nanoparticles

2014 ◽  
Vol 1694 ◽  
Author(s):  
Daniel Rivera-Vázquez ◽  
Yohaselly Santiago-Rodríguez ◽  
Miguel A. González ◽  
Miguel E. Castro-Rosario
Keyword(s):  
Optical Absorption ◽  
Absorption Spectra ◽  
Quantum Confinement ◽  
Visible Region ◽  
Calcium Sulfide ◽  
Optical Absorption Spectra ◽  
Confinement Effects ◽  
Absorption Bands ◽  
Long Wavelength ◽  
Quantum Confinement Effects

ABSTRACTCalcium sulfide (CaS) nanoparticles are cadmium free fluorescent nanostructures with potential applications in nanomedicine and photovoltaic cells. We report on the synthesis and optical properties of CaS nanoparticles prepared by the reaction of Ca(CH3CO2)2 and DMSO in a microwave. The absorption spectra of CaS prepared from this method consists of a well-defined peak in the UV and a long wavelength tail that extends above 700 nm. Emission bands centered at around 500 nm with a long wavelength tail that extends above 600 nm are observed upon excitation at 405 nm. STM measurements reveal the formation of CaS nanoparticles with an average diameter of (3.2 ± 0.7) nm. The direct and indirect band gaps are estimated to be (0.403 ± 0.003) eV and (4.135 ± 0.006) eV, respectively. Theoretical calculations on small CaS clusters are used to establish the physical properties of calcium sulfide nanoclusters, including the optical absorption spectra. Unique to CaS nanostructures is the absorption of light at wavelengths longer that in the bulk material instead of the blue shift associated with quantum confinement effects in semiconductors. Indeed, the strong absorption bands in the visible region of the spectra of the CaS nanostructures do not have a counterpart in the gas or solid phases. The optical absorption spectra are proposed to have a significant contribution from indirect transitions which are discussed in terms of the dispersion of the phonon frequency.

Optical Absorption and Photoluminescence Properties of Dy3+ Ions in Bi2O3-SiO2-B2O3 Glass System

2014 ◽  
Vol 979 ◽  
pp. 280-284
Author(s):  
Narong Sangwaranatee ◽  
Yaowaluk Tariwong ◽  
Sunisa Sarachai ◽  
Jakrapong Kaewkhao ◽  
Natthakridta Chanthima
Keyword(s):  
Optical Absorption ◽  
Emission Spectrum ◽  
Molar Volume ◽  
Borosilicate Glass ◽  
Excitation Wavelength ◽  
Optical Absorption Spectra ◽  
Photoluminescence Spectra ◽  
Photoluminescence Properties ◽  
Melt Quenching ◽  
Absorption Bands

This research studied the effect of dysprosium on the physical, optical and luminescence properties of the bismuth borosilicate glass in compositions 40Bi2O3 : 20SiO2 : (40-x)B2O3 : xDy2O3 (where x = 0.0, 0.5, 1.0, 1.5, 2.0 and 2.5 mol%). The glass systems have been prepared at 1100 °C by melt quenching technique. The results showed that the density and molar volume of glass samples are between 4.6477 ± 0.0020 to 5.0047 ± 0.0041 g/cm3 and 45.6608 to 48.6797 cm3/mol, respectively. The values of density and molar volume of these glasses were not depend on the Dy2O3 concentration. The optical absorption spectra of glass samples in the UV-Vis-NIR region shows absorption bands at 794, 906, 1094, 1276 and 1690 nm, respectively. The photoluminescence spectra show emission bands at 482 (blue), 576 (green), 663 (yellow) and 756 (red) nm under 453 nm excitation wavelength. The emission spectrum at 576 nm has shown a strongest intensity.

scholarly journals Optical absorption of LiNaGe4O9:Mn crystal

2021 ◽  
Vol 29 (1) ◽  
pp. 69-72
Author(s):  
A. Yu. Osetsky ◽  
T. V. Panchenko ◽  
M. D. Volnianskii ◽  
M. P. Trubitsyn
Keyword(s):  
Field Theory ◽  
Optical Absorption ◽  
Ferroelectric Phase Transition ◽  
Ferroelectric Phase ◽  
Optical Absorption Spectra ◽  
Crystal Field Theory ◽  
Absorption Bands ◽  
Additional Absorption ◽  
Impurity Ions ◽  
Semi Empirical

The paper reports the results of optical absorption spectra studying in LiNaGe4O9 crystal doped with Mn. It is shown that Mn impurity causes the appearance of the additional absorption bands. The intensities of these bands change in different ways in the range of the ferroelectric phase transition. Semi-empirical version of the crystal field theory is used to discuss localization and charge state of Mn impurity ions in the LiNaGe4O9 structure.

QUANTUM CONFINEMENT IN COATED NANOPARTICLES

1996 ◽  
Vol 03 (01) ◽  
pp. 133-136 ◽  
Author(s):  
H.S. ZHOU ◽  
I. HONMA ◽  
K.H. KIM ◽  
H. KOMIYAMA ◽  
H. SASABE ◽  
...  
Keyword(s):  
Optical Absorption ◽  
Theoretical Approach ◽  
Quantum Confinement ◽  
Optical Absorption Spectra ◽  
Shell Layer ◽  
Resonance Effects ◽  
Coated Nanoparticles ◽  
Electromagnetic Resonance ◽  
Colloidal Method ◽  
Confinement Model

We synthesize CdS/PbS -coated nanoparticles and investigate the spectra of their optical absorption and photoluminescence (PL). The experimental results can be explained by the quantum-confinement model in coated semiconductor nanoparticles. We also prepare gold-coated nanoparticles with a nonmetallic core Au 2 S by a two-step colloidal method, and observe the extraordinary optical absorption spectra of the coated samples. The results are consistent with a theoretical approach that includes electromagnetic resonance effects and the quantum confinement of the carriers in the thin gold shell layer.

Optical Absorption of Doped and Undoped Bulk SiC

2000 ◽  
Vol 640 ◽  
Author(s):  
K. Miller ◽  
Q. Zhou ◽  
J. Chen ◽  
M. O. Manasreh ◽  
Z. C. Feng ◽  
...  
Keyword(s):  
Silicon Carbide ◽  
Optical Absorption ◽  
Band Gap ◽  
Absorption Spectra ◽  
Spectral Region ◽  
Sharp Peak ◽  
Band Edge ◽  
Optical Absorption Spectra ◽  
Bulk Silicon ◽  
Free Carriers

ABSTRACTOptical absorption spectra of undoped, n-type, and semi-insulating 6H and 4H bulk silicon carbide (SiC) were obtained in the spectral region of 200 – 3200 nm (6.20 – 0.3875 eV). Several features were observed in the absorption spectra collected for various samples. A sharp peak below the band gap was observed in 4H SiC. The intensity of this peak was observed to increase in samples that exhibit larger absorption due to free carriers, which leads us to conclude that the defect responsible for this peak is also the source of the free carriers in the materials. Additionally, a series of optical absorption peaks separated by approximately 21 meV were observed around 0.9185 eV (1350 nm). These peaks are zero phonon lines of intraband transitions in the VSi 3d shell. The optical absorption near the band edge was observed to be sample dependent. The variation of the band gap as a function of temperature is also observed to be sample dependent.

The role of dysprosium ions on the physical and optical properties of lithium-borosulfophosphate glasses

2017 ◽  
Vol 31 (13) ◽  
pp. 1750101 ◽  
Author(s):  
Ibrahim Bulus ◽  
S. A. Dalhatu ◽  
R. Hussin ◽  
W. N. Wan Shamsuri ◽  
Y. A. Yamusa
Keyword(s):  
Optical Properties ◽  
Optical Absorption ◽  
Absorption Spectra ◽  
Physical Parameters ◽  
Potential Candidate ◽  
Optical Absorption Spectra ◽  
Absorption Bands ◽  
X Ray ◽  
Nir Absorption ◽  
Optical Applications

Achieving outstanding physical and optical properties of borosulfophosphate glasses via controlled doping of rare earth ions is the key issue in the fabrication of new and highly-efficient glass material for diverse optical applications. Thus, the effect of replacing P2O5 by Dy2O3 on the physical and optical properties of Dy[Formula: see text]-doped lithium-borosulfophosphate glasses with chemical composition of 15Li2O–30B2O3–15SO3–[Formula: see text]P2O5–[Formula: see text]Dy2O3 (where 0.0 mol.% [Formula: see text] mol.%) has been investigated. The glass samples were synthesized from high-purity raw materials via convectional melt-quenching technique and characterized by X-ray diffraction (XRD), energy-dispersive X-ray spectrometry (EDX), density and UV–vis–NIR absorption measurements. The amorphous nature of the prepared glass samples was confirmed by XRD patterns whereas the EDX spectrum depicts elemental traces of O, C, B, S, P and Dy. The physical parameters such as density, refractive index, molar volume, polaron radius and field strength were found to vary nonlinearly with increasing Dy2O3 concentration. UV–vis–NIR absorption spectra revealed seven absorption bands with most dominant peak at 1269 nm (6H[Formula: see text]F[Formula: see text]H[Formula: see text]). From the optical absorption spectra, the optical bandgap and Urbach’s energy have been determined and are related with the structural changes occurring in these glasses with increase in Dy2O3 content. Meanwhile, the bonding parameters ([Formula: see text]) evaluated from the optical absorption spectra were found to be ionic in nature. The superior features exhibited by the current glasses nominate them as potential candidate for nonlinear optical applications.

Notizen: Preparation, Structures and Optical Properties of [H3N(CH2)6NH3]BiX5 (X=I, Cl) and [H3N(CH2)6NH3]SbX5 (X=I, Br)

1998 ◽  
Vol 53 (8) ◽  
pp. 927-932 ◽  
Author(s):  
G. A. Mousdis ◽  
G. C. Papavassiliou ◽  
A. Terzis ◽  
C. P. Raptopoulou
Keyword(s):  
Optical Properties ◽  
Optical Absorption ◽  
Crystal Structures ◽  
Absorption Spectra ◽  
Blue Shift ◽  
Optical Absorption Spectra ◽  
Absorption Bands ◽  
One Dimensional ◽  
Excitonic Absorption

Abstract The preparation, crystal structures and optical absorption spectra of [H3N(CH2)6NH3]BiX5 (X= I, Cl) and [H3N(CH2)6NH3]SbX5 (X =I, Br) are reported. The anions of the compounds consist of MX6-octahedra (M =Bi, Sb) sharing cisvertices in one-dimensional zig-zag chains. Because of their one-dimensional character, a blue shift of the excitonic absorption bands, in com parison to those of higher dim ensionality systems (MX3), is observed.

QUANTUM CONFINEMENT AND COULOMB EFFECTS IN SEMICONDUCTOR QUANTUM DOTS

1990 ◽  
Vol 04 (16) ◽  
pp. 1009-1016 ◽  
Author(s):  
Y.Z. HU ◽  
S.W. KOCH ◽  
D.B. TRAN THOAI
Keyword(s):  
Quantum Dots ◽  
Optical Absorption ◽  
Absorption Spectra ◽  
Quantum Confinement ◽  
Semiconductor Quantum Dots ◽  
Optical Absorption Spectra ◽  
Electron Hole ◽  
Quantum Confinement Effects ◽  
Electron Hole Pair ◽  
Coulomb Effects

Coulomb and quantum confinement effects in small semiconductor microcrystallites are analyzed. Energies and wavefunctions for one- and two-electron-hole-pair states are computed and optical absorption spectra are evaluated.

Optical Absorption Spectra of KBr:Pb2+ Crystals

1973 ◽  
Vol 51 (21) ◽  
pp. 2242-2248 ◽  
Author(s):  
Robert E. Chaney ◽  
P. W. M. Jacobs ◽  
Taiju Tsuboi
Keyword(s):  
Optical Absorption ◽  
Absorption Spectra ◽  
Alkali Halide ◽  
Room Temperature ◽  
Nonlinear Least Squares ◽  
Energy Separation ◽  
Optical Absorption Spectra ◽  
Absorption Bands ◽  
Fundamental Properties ◽  
Alkali Halide Crystals

The fundamental properties of the absorption spectra of KBr:Pb2+ crystals have been studied at various temperatures from the liquid helium range to room temperature. The observed absorption bands are assigned to the so-called A, B, C, and D' bands by analogy with the absorption bands of other s2-configuration ions in alkali halide crystals. The B, C, and D′ bands overlap but have been resolved into their components by nonlinear least squares analysis. A discussion is given of the energy separation between the B and C bands in Sn2+-, Tl+-, and Pb2+-doped alkali halide crystals.

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