Band-To-Band Transitions in Poly (Phenyl Methyl Silane)

1989 ◽  
Vol 173 ◽  
Author(s):  
R. G. Kepler ◽  
J.M. Zeigler
Keyword(s):  
Experimental Data ◽  
Band Gap ◽  
Quantum Efficiency ◽  
Photon Energy ◽  
Absorption Peak ◽  
Strong Absorption ◽  
Exciton Band ◽  
Carrier Generation ◽  
Strong Absorption Peak

ABSTRACTWe have measured the quantum efficiency for carrier generation as a function of photon energy and the electroabsorption spectrum in poly (phenyl methyl silane). The experimental data are consistent with a band gap of about 4.6 eV. A strong absorption peak which is observed at 3.7 eV is shown to be an exciton band.

Highly Tm Doped Silica Optical Preform by MCVD - Chelate Vapor Delivery (Soot-Dopant Stepwise Technique)

2018 ◽  
Vol 780 ◽  
pp. 57-61 ◽  
Author(s):  
K.A. Mat-Sharif ◽  
Nasr Y.M. Omar ◽  
M.I. Zulkifli ◽  
S.Z. Muhd-Yassin ◽  
Y.K. Sin ◽  
...  
Keyword(s):  
Refractive Index ◽  
Absorption Spectrum ◽  
Chemical Vapor Deposition ◽  
Vapor Deposition ◽  
Chemical Vapor ◽  
Absorption Peak ◽  
Strong Absorption ◽  
Silica Fiber ◽  
Index Variation ◽  
Strong Absorption Peak

This paper presents the progress in the fabrication of highly doped thulium silica fiber. As much as 5.3 wt. % Tm alongside 7.1 wt. % Al (co-dopant) were incorporated into silica preform. The preform was fabricated using the Modified Chemical Vapor Deposition (MCVD)-chelate vapor delivery with soot-dopant stepwise technique. The preform was analyzed for several key properties such as refractive index variation along deposition length, dopants distribution profiles and UV-Vis absorption. The results showed a homogeneous dopants distribution with 4% RSD in the longitudinal refractive index along a 40 cm preform length. The UV-Vis absorption spectrum exhibited a strong absorption peak at 790 nm attributed to Tm 3H4 energy manifold.

scholarly journals Colorimetric determination of ascorbic acid based on carbon quantum dots as peroxidase mimetic enzyme

RSC Advances ◽  
2020 ◽  
Vol 10 (25) ◽  
pp. 14953-14957 ◽  
Author(s):  
Xin Shu ◽  
Yuwai Chang ◽  
Huizhong Wen ◽  
Xiaotiao Yao ◽  
Yilin Wang
Keyword(s):  
Quantum Dots ◽  
Ascorbic Acid ◽  
Carbon Quantum Dots ◽  
Absorption Peak ◽  
Strong Absorption ◽  
Colorimetric Determination ◽  
Mimetic Enzyme ◽  
Peroxidase Mimetic ◽  
Strong Absorption Peak

Carbon quantum dots (CQDs) were synthesized from litchi peel, exhibiting a peroxidase-like activity and enabling the oxidation of 3,3′,5,5′-tetramethylbenzidine (TMB) in association with H2O2 to generate blue oxidized TMB (ox-TMB) with a strong absorption peak at 652 nm.

Synthesis of Platinum nanoparticles by Gamma Radiolysis

MRS Advances ◽  
2018 ◽  
Vol 3 (42-43) ◽  
pp. 2537-2557 ◽  
Author(s):  
Takalani Cele ◽  
Malik Maaza ◽  
Alain Gibaud
Keyword(s):  
Gamma Radiation ◽  
Aqueous Solutions ◽  
Gamma Irradiation ◽  
Platinum Nanoparticles ◽  
Pt Nanoparticles ◽  
Absorption Peak ◽  
Strong Absorption ◽  
Gamma Radiolysis ◽  
Strong Absorption Peak

AbstractThe synthesis of Platinum (Pt) nanoparticles by gamma irradiation is presented. The 0.1 M Pt solution of different concentration was prepared from K2PtCl4. The platinum aqueous solutions were irradiated by gamma radiation at a dose of 70, 90 and 120 kGy. The findings show the effect of irradiation on PtII solutions with different concentrations. The big black particles that are fairly agglomerated when the concentration was above 0.0050 M were observed. The UV-Vis spectrum of Pt of different concentrations shows a strong absorption peak at the wavelength 261 nm after irradiation, which indicates the presence of platinum nanoparticles. Furthermore, FTIR, XRD and HRTEM images also confirmed the presence of the nanoparticles produced by Radiolysis. The size of the Pt nanoparticles was found to be 7.39 nm.

TWO PHOTON PHOTOCONDUCTIVITY OF ZnS USING XeCl LASER

2003 ◽  
Vol 17 (24) ◽  
pp. 1265-1270 ◽  
Author(s):  
R. D. SINGH ◽  
D. S. AHLAWAT ◽  
ARUN GAUR
Keyword(s):  
Band Gap ◽  
Photon Energy ◽  
Xecl Laser ◽  
Two Photon ◽  
Comparison Of Results ◽  
Photon Excitation ◽  
Enhanced Mobility ◽  
Two Photon Excitation

Log Q versus log I ph characteristics and laser enhanced mobility in the case of ZnS have been studied using a XeCl laser. The comparison of results in this case with multiphoton photoconductivity of other materials indicates two photon excitation from a lower valance band, wherefrom one-photon excitation is forbidden but two-photon excitation is allowed. Since the band-gap of ZnS is smaller than the photon energy of the XeCl laser, the result seems to be interesting.

Optical Activity of Yb3+ in MeV Ion-Implanted InP.

1993 ◽  
Vol 301 ◽  
Author(s):  
S. Uekusa ◽  
A. Majima ◽  
H. Katsumata ◽  
Y. Noyori ◽  
M. Kumagai
Keyword(s):  
Band Gap ◽  
Photon Energy ◽  
Luminescence Intensity ◽  
Annealing Temperature ◽  
Rare Earth Ions ◽  
Excitation Wavelength ◽  
Photoluminescence Excitation ◽  
Efficient Energy Transfer ◽  
Transfer Processes ◽  
Impurities And Defects

ABSTRACTFor the evaluation of an implanted layer, photoluminescence (PL) and photoluminescence excitation (PLE) measurements, which are nondestructive and sensitive methods for identifying impurities and defects, were performed. Yb3+ -related sharp luminescence was observed at a wavelength of 1002nm, due to the transitions which occurred between the spin-orbit levels 2F5/2→2F7/2 of Yb3+ (4f13). Most efficient luminescence of Yb3+ was achieved at an excitation wavelength of around 880nm. The luminescence intensity of this peak (Yb3+) decreased with an increase in annealing temperature. Since the peak has not been observed for good samples in crystallinity, it may indicate that new, efficient energy transfer processes to rare-earth ions occur through the defect energy level. Especially, for the sample annealed at 600°C, Yb-related luminescence intensity excited by the photon energy below the band gap is about 3 times larger than that of excited by the photon energy above the band gap.

Atomistic Calculations of Dopant Binding Energies in ZnGeP2

1997 ◽  
Vol 484 ◽  
Author(s):  
Ravindra Pandey ◽  
Melvin C. Ohmer ◽  
A. Costales ◽  
J. M. Recio
Keyword(s):  
Experimental Data ◽  
Band Gap ◽  
Interatomic Potential ◽  
Host Lattice ◽  
Binding Energies ◽  
First Principle ◽  
Atomistic Model ◽  
Group Iii ◽  
Atomistic Calculations

AbstractAtomistic model has been applied to study various cation dopants, namely Cu, Ag, B, Al, Ga and In in ZnGeP2. The pairwise interatomic potential terms representing the interaction of dopants with the host lattice ions are derived using first principle methods. Defect calculations based on Mott-Littleton methodology predict small binding energies for Cu and Ag substituting Zn in the lattice which are in agreement with the available experimental data. The group III dopants (i.e. B, Al, Ga and In) at the Ge site are predicted to have large binding energies for a hole except B which shows a distinct behavior. This may be due to large mismatch in atomic sizes of B and Ge. At the Zn site, the calculated binding energies of the group III dopants place donor levels in the middle of the band gap.

scholarly journals Температурная зависимость ширины запрещенной зоны монокристаллов MnAgIn-=SUB=-7-=/SUB=-S-=SUB=-12-=/SUB=-

2019 ◽  
Vol 53 (12) ◽  
pp. 1621
Author(s):  
И.В. Боднарь ◽  
Б.Т. Чан ◽  
В.Н. Павловский ◽  
И.Е. Свитенков ◽  
Г.П. Яблонский
Keyword(s):  
Experimental Data ◽  
Temperature Dependence ◽  
Band Gap ◽  
Single Crystals ◽  
Spinel Structure ◽  
Semiconductor Materials ◽  
Transmittance Spectra ◽  
Temperature Range

AbstractMnAgIn_7S_12 single crystals 16 mm in diameter and ~40 mm in length are grown by planar crystallization of the melt. It is shown that the material grown crystallizes with the formation of the cubic spinel structure. From the transmittance spectra recorded in the region of fundamental absorption in the temperature range 10–320 K, the band gap E _ g of the single crystals and its temperature dependence are determined. The dependence has a shape typical of most semiconductor materials: as the temperature is lowered, the band gap E _ g increases. A calculation is carried out, and it is shown that the calculated values are in agreement with the experimental data.

The Role of Reduced Graphene Oxide Concentration as Ablated Material on Optical Properties of Graphene Quantum Dots

2019 ◽  
Vol 948 ◽  
pp. 267-273 ◽  
Author(s):  
Fiqhri Heda Murdaka ◽  
Ahmad Kusumaatmaja ◽  
Isnaeni ◽  
Iman Santoso
Keyword(s):  
Quantum Dots ◽  
Optical Properties ◽  
Graphene Oxide ◽  
Band Gap ◽  
Reduced Graphene Oxide ◽  
Optical Band Gap ◽  
Graphene Quantum Dots ◽  
Absorption Peak ◽  
Oxygen Defect ◽  
Reduced Graphene

We report the synthesize of Graphene Quantum Dots (GQDs) using ablation method with reduced Graphene Oxide (rGO) solution as a starting material. We have varied the concentration of rGO as following: 0.5, 2, 5 mg/ml and then have ablated them using 800 nm Ti-Sapphire femtosecond laser to obtain GQDs. From the UV-Vis data, we observed that the more concentration of rGO is being ablated, the more secondary absorption peak at 255.1 nm appeared. This secondary absorption peak is a characteristic of n-π* bonding due to the presence of oxygen defect which occurs as a result of the interaction between the laser and the water in rGO solution. We conclude that the population of oxigen defect in GQDs is increasing, following the increase of rGO concentration and could alter the optical properties of GQD. On the other hand, using Tauc’s plot, we confirm that the increase of rGO concentration as the ablated material does not alter GQDs optical band gap. However, it will slightly reduce both, direct and indirect Oxygen defect related optical band gap.

Thickness-dependent internal quantum efficiency of narrow band-gap polymer-based solar cells

2015 ◽  
Vol 143 ◽  
pp. 242-249 ◽  
Author(s):  
Hoon Park ◽  
Jongdeok An ◽  
Jongwoo Song ◽  
Myounghee Lee ◽  
Hyuntak Ahn ◽  
...  
Keyword(s):  
Solar Cells ◽  
Band Gap ◽  
Quantum Efficiency ◽  
Narrow Band ◽  
Internal Quantum Efficiency
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