Defects induced changes in the electronic structures of MgO and their correlation with the optical properties: a special case of electron–hole recombination from the conduction band

RSC Advances ◽  
2016 ◽  
Vol 6 (98) ◽  
pp. 96398-96415 ◽  
Author(s):  
Nimai Pathak ◽  
Partha Sarathi Ghosh ◽  
Santosh K. Gupta ◽  
Ramakant Mahadeo Kadam ◽  
Ashok Arya
Keyword(s):  
Optical Properties ◽  
Dft Calculations ◽  
Conduction Band ◽  
Electronic Structures ◽  
Electron Hole ◽  
Induced Changes ◽  
Special Case ◽  
Hole Recombination ◽  
Tunable Emission

Defect induced tunable emission in MgO is investigated using photoluminescence and DFT calculations.

Optically Detected Magnetic Resonance and Double Beam Photoluminescence of CdS/HgS/CdS Nanoparticles

1998 ◽  
Vol 536 ◽  
Author(s):  
H. Porteanu ◽  
A. Glozman ◽  
E. Lifshitz ◽  
A. Eychmüller ◽  
H. Weller
Keyword(s):  
Optical Properties ◽  
Magnetic Resonance ◽  
Cds Nanoparticles ◽  
Electron Hole ◽  
Cladding Layer ◽  
Double Beam ◽  
Optically Detected Magnetic Resonance ◽  
Optically Detected ◽  
Cladding Layers ◽  
Hole Recombination

AbstractCdS/HgS/CdS nanoparticles consist of a CdS core, epitaxially covered by one or two monolayers of HgS and additional cladding layers of CdS. The present paper describes our efforts to identify the influence of CdS/HgS/CdS interfaces on the localization of the photogenerated carriers deduced from the magneto-optical properties of the materials. These were investigated by the utilization of optically detected magnetic resonance (ODMR) and double-beam photoluminescence spectroscopy. A photoluminescence (PL) spectrum of the studied material, consists of a dominant exciton located at the HgS layer, and additional non-excitonic band, presumably corresponding to the recombination of trapped carriers at the interface. The latter band can be attenuated using an additional red excitation. The ODMR measurements show the existence of two kinds of electron-hole recombination. These electron-hole pairs maybe trapped either at a twin packing of a CdS/HgS interface, or at an edge dislocation of an epitaxial HgS or a CdS cladding layer.

The Effect of Chromium on the Optical Properties and Photoactivity of Nano-Particulate Rutile

2012 ◽  
Vol 554-556 ◽  
pp. 502-506 ◽  
Author(s):  
Li Wei Wang ◽  
Terry A. Egerton
Keyword(s):  
Optical Properties ◽  
Photocatalytic Activity ◽  
Reflectance Spectroscopy ◽  
Electron Trapping ◽  
Electron Hole ◽  
High Chromium ◽  
Chromium Doping ◽  
Chromium Addition ◽  
Co Precipitation ◽  
Hole Recombination

Chromium doped rutile TiO2was synthesized by either co-precipitation or impregnation (surface-doping) and characterized by XRD and reflectance spectroscopy. Chromium addition did not change the TiO2structure nor did the structure of the co-precipitated products differ from that of the impregnated samples. However, chromium doping moved the absorption of both sets of products into the visible and significantly affected the TiO2photocatalytic activity for isopropanol (IPA) oxidation. At high chromium concentrations the photoactivity of the co-precipitated samples was reduced by a larger amount than that of the impregnated samples; this was attributed to a higher concentration of Cr3+ions in the rutile lattice. Unexpectedly, increased photoactivity was measured for low Cr levels of surface-doped rutile. This may be caused by increased electron-trapping, at surface Cr6+ions, and correspondingly reduced, electron-hole recombination.

Modulating the atomic and electronic structures through alloying and heterostructure of single-layer MoS2

2014 ◽  
Vol 2 (7) ◽  
pp. 2101-2109 ◽  
Author(s):  
Xiao-Lin Wei ◽  
Hui Zhang ◽  
Gen-Cai Guo ◽  
Xi-Bo Li ◽  
Woon-Ming Lau ◽  
...  
Keyword(s):  
Photocatalytic Activity ◽  
Charge Density ◽  
Electronic Structures ◽  
Single Layer ◽  
Electron Hole ◽  
Hole Recombination ◽  
Spontaneous Separation

Charge density of the VBM (green) and CBM (blue) for armchair MoS2–WS2 heterostructures, indicating the spontaneous separation of photo-generated electrons and holes, which could strongly enhance the photocatalytic activity due to suppression of the electron–hole recombination.

Tuning band gaps and optical absorption of BiOCl through doping and strain: insight form DFT calculations

2017 ◽  
Vol 19 (31) ◽  
pp. 20968-20973 ◽  
Author(s):  
Le Zhang ◽  
Zhen-Kun Tang ◽  
Woon-Ming Lau ◽  
Wen-Jin Yin ◽  
Shu-Xian Hu ◽  
...  
Keyword(s):  
Optical Properties ◽  
Optical Absorption ◽  
Dft Calculations ◽  
Electronic Structures ◽  
Band Gaps ◽  
First Principle ◽  
First Principle Calculations

Doping and strain were used to tune the electronic structures and optical properties of BiOCl using first principle calculations.

First-Principle Study of the Electronic and Optical Properties of Ti Doped ZnS

2012 ◽  
Vol 430-432 ◽  
pp. 173-176 ◽  
Author(s):  
Chang Peng Chen ◽  
Jian Xiong Xie ◽  
Jia Fu Wang
Keyword(s):  
Optical Properties ◽  
Fermi Level ◽  
Conduction Band ◽  
Electronic Structures ◽  
Density Functional ◽  
Band Gaps ◽  
First Principle ◽  
Level Shifts ◽  
Calculation Results ◽  
Impurity Elements

Based on the density functional pseudopotential method, the electronic structures and the optical properties for Ti doped ZnS are investigated in detail. The calculation results indicate that the doping of Ti widens the band gap of ZnS and the Fermi level shifts upward into the conduction band. The impurity elements form new highly localized impurity energy level at the bottom of the conduction band near the Fermi level.,.Meanwhile, blue shifts are revealed in both the imaginary part of dielectric function and the absorption spectra corresponding to the change of band gaps.

Optical limiting and singlet oxygen generation properties of phosphorus triazatetrabenzcorroles

2015 ◽  
Vol 19 (01-03) ◽  
pp. 192-204 ◽  
Author(s):  
Colin Mkhize ◽  
Jonathan Britton ◽  
John Mack ◽  
Tebello Nyokong
Keyword(s):  
Optical Properties ◽  
Dipole Moment ◽  
Dft Calculations ◽  
Singlet Oxygen ◽  
Electronic Structures ◽  
Optical Limiting ◽  
Oxygen Generation ◽  
Singlet Oxygen Generation ◽  
Td Dft ◽  
Benzene Rings

Novel phosphorus triazatetrabenzcorrole (TBC) tetrasubstituted at the α- and β-positions of the peripheral fused benzene rings with t-butylphenoxy substituents have been prepared and characterized. The effect of the substituents on the electronic structures and optical properties is investigated with TD-DFT calculations and MCD spectroscopy. The optical limiting properties have been investigated to examine whether the lower symmetry that results from the direct pyrrole–pyrrole bond and hence the permanent dipole moment that is introduced result in higher safety thresholds, relative to the values that have been reported for phthalocyanines. The suitability of the compounds for singlet oxygen applications has also been examined.

Theoretical study on nanostructural modifications of the Si(111) surface

2019 ◽  
Vol 18 (01) ◽  
pp. 1950005
Author(s):  
Yue-Hang Dong ◽  
Xiao-Hui Liu ◽  
Wan-Sheng Su ◽  
Li-Zhen Zhao ◽  
Qing-Jun Zang ◽  
...  
Keyword(s):  
Density Functional Theory ◽  
Optical Properties ◽  
Optical Absorption ◽  
Dft Calculations ◽  
Electronic Structures ◽  
Density Functional ◽  
Theoretical Study ◽  
Surface Modifications ◽  
Thermal Stabilities ◽  
Functional Theory

Modified Si(111) surface with designed nanostructural modifications including grown pits, nanobars and nanoislands as well as deposited hill-, diamond- and cage-like nanoclusters were studied using density-functional theory (DFT) calculations. The thermal stabilities, electronic structures and optical properties of these various nanostructural modifications of the Si(111) surface were calculated and discussed. The results indicate that the optical absorption of the modified Si(111) surface can be enhanced by these surface modifications especially when depositing diamond-like nanoclusters on the surface.

MCD spectroscopy and TD-DFT calculations of magnesium tetra-(15-crown-5-oxanthreno)-phthalocyanine

2016 ◽  
Vol 20 (01n04) ◽  
pp. 505-513 ◽  
Author(s):  
John Mack ◽  
Scebi Mkhize ◽  
Evgeniya A. Safonova ◽  
Alexander G. Martynov ◽  
Yulia G. Gorbunova ◽  
...  
Keyword(s):  
Optical Properties ◽  
Dft Calculations ◽  
Electronic Structures ◽  
Additional Insight ◽  
Visible Absorption ◽  
Model Complexes ◽  
B3lyp Functional ◽  
Td Dft ◽  
Uv Visible ◽  
Insight Into

An analysis of the MCD spectroscopy and TD-DFT calculations of magnesium tetra-(15-crown-5-oxanthreno)-phthalocyanine is reported. This study provides a reassessment of an earlier study on the nature of the bands in UV-visible absorption spectra of magnesium and zinc tetra-(15-crown-5-oxanthreno)-phthalocyanine that was based on an analysis of TD-DFT calculations for a series of model complexes with the B3LYP functional. A detailed analysis of MCD spectral data and TD-DFT calculations with the CAM-B3LYP functional for the complete Mg(II) complex provides an additional insight into the optical properties and electronic structures of tetra-(15-crown-5-oxanthreno)-phthalocyanines. Thus, the bands in the Q-band region are reassigned as being due exclusively to the Q transition of Gouterman’s 4-orbital model, since intense pseudo-[Formula: see text] terms are observed in the MCD spectrum in a spectral region that had previously been assigned as charge transfer bands.

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