Role of the Zhang-Rice-like exciton in optical absorption spectra ofCuGeO3andCuGe1−xSixO3single crystals

2002 ◽  
Vol 66 (2) ◽  
Author(s):  
S. Pagliara ◽  
F. Parmigiani ◽  
P. Galinetto ◽  
A. Revcolevschi ◽  
G. Samoggia
Keyword(s):  
Optical Absorption ◽  
Absorption Spectra ◽  
Optical Absorption Spectra

scholarly journals Photoelectrochemistry of Ferrites: Theoretical Predictions vs. Experimental Results

2020 ◽  
Vol 234 (4) ◽  
pp. 719-776 ◽  
Author(s):  
Anna C. Ulpe ◽  
Katharina C.L. Bauerfeind ◽  
Luis I. Granone ◽  
Arsou Arimi ◽  
Lena Megatif ◽  
...  
Keyword(s):  
Optical Absorption ◽  
Electronic Properties ◽  
Absorption Spectra ◽  
Raman Spectra ◽  
First Principles ◽  
Experimental Results ◽  
Atomic Scale ◽  
Optical Absorption Spectra ◽  
Photoelectrochemical Activity

AbstractThis paper gives an overview about recent theoretical and experimental work on electronic and optical properties of spinel ferrites MFe2O4. These compounds have come into focus of research due to their possible application as photocatalyst material for photoelectrochemical water splitting. The theoretical background of state-of-the-art quantum-chemical approaches applied for predicting electronic and optical band gaps, absolute band positions, optical absorption spectra, dielectric functions and Raman spectra, is briefly reviewed. Recent applications of first-principles methods on magnetic and electronic properties of ferrites with M = Mg and the first row of subgroup elements Sc to Zn are presented, where it is shown that the fundamental band gap is strongly dependent on the spin state and the degree of inversion of the spinel structure. The observed variation of electronic properties may serve as an explanation for the large scattering of experimental results. The exchange of M and Fe cations has also a pronounced effect on the Raman spectra of ferrites, which is analyzed at atomic scale from first principles. Calculated optical absorption spectra of ferrites are compared to experimental spectra. The electronic nature of the first excitations and the role of oxygen vacancies are discussed. For the calculation of absolute band positions, which have a significant impact on the photoelectrochemical activity of the ferrites, models of the most stable ferrite surfaces are developed that take into account their polar nature and the interaction with the solvent. Theoretically predicted valence and conduction band edges are compared to results from electrochemical measurements. The role of cation exchange on the surface electronic structure is investigated both theoretically and experimentally.

Role of OH- Ions on the Optical Absorption Spectra of Pure and Doped KMgF3 Fluoroperovskite

1997 ◽  
Vol 239-241 ◽  
pp. 449-452 ◽  
Author(s):  
P. Beneventi ◽  
P. Bertoli ◽  
Rosanna Capelletti ◽  
R. Francini ◽  
U.M. Grassano ◽  
...  
Keyword(s):  
Optical Absorption ◽  
Absorption Spectra ◽  
Optical Absorption Spectra

Control of the Luminescence Properties in Polythiophenes Solutions by Interring Rotational Disorder

1997 ◽  
Vol 488 ◽  
Author(s):  
S. Luzzati ◽  
G. Bongiovanni ◽  
M. Catellani ◽  
M. A. Loi ◽  
A. Milani ◽  
...  
Keyword(s):  
Chemical Composition ◽  
Optical Absorption ◽  
Absorption Spectra ◽  
Luminescence Spectra ◽  
Visible Range ◽  
Optical Absorption Spectra ◽  
Photoluminescence Properties ◽  
Dilute Solutions ◽  
Thiophene Based Polymers

AbstractThe photoluminescence properties of thiophene-based polymers obtained by the random copolymerization of 3,4-dibutylthiophene and 3-butylthiophene are reported. Optical absorption spectra, cw photolumninescence (PL) spectra, PL quantum efficiencies and PL decays have been measured in dilute solutions. By varying the copolymer chemical composition it is possible to tune the intensity and the color of the luminescence spectra in the whole visible range. We evidence the role of disorder, controlled by interring rotations, as the tuning factor for the disexcitation pathway of the photoexcitations in these materials.

scholarly journals Энергетический спектр и оптическое поглощение углеродных наносистем на примере изомеров N 11 и 22 фуллерена С-=SUB=-84-=/SUB=-

2020 ◽  
Vol 62 (3) ◽  
pp. 484
Author(s):  
А.И. Мурзашев
Keyword(s):  
Experimental Data ◽  
Optical Properties ◽  
Optical Absorption ◽  
Absorption Spectra ◽  
Coulomb Interaction ◽  
Energy Spectra ◽  
Optical Absorption Spectra ◽  
Electronic And Optical Properties ◽  
Comparison Of The Results

Abstract The energy spectra of isomers nos. 11 and 22 of C_84 fullerene is obtained with allowance for the intrasite Coulomb interaction. Based on the obtained spectra, the optical absorption spectra of these systems are simulated. The obtained optical absorption spectra qualitatively agree well with the available experimental data. In addition, the optical absorption spectra are also calculated on the base of the energy spectra of each of the systems calculated without considering the intrasite Coulomb interaction. The comparison of the results obtained in these different models strongly demonstrates the most important role of the Coulomb interaction in the formation of the electronic and optical properties of these systems.

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