Interpretation of electronic spectra of linear polynuclear p-quinones by the method of configuration analysis

1981 ◽  
Vol 46 (1) ◽  
pp. 20-30 ◽  
Author(s):  
Miloš Nepraš ◽  
Jürgen Fabian ◽  
Miloš Titz
Keyword(s):  
Charge Transfer ◽  
Absorption Band ◽  
Electronic Spectra ◽  
Charge Transfer Transitions

Character of transition in a series of linear p-quinones has been investigated on the basis of configuration analysis. Correlation graphs of the states have been constructed enabling interpretation of the spectra in the terms of local transitions in the fragments and charge-transfer transitions between the fragments. Influence of various types of annelation on the first ππ* absorption band in the spectra of the mentioned compound class has been investigated qualitatively from the viewpoint of interaction of the frontier MOs of the fragments.

scholarly journals Локализованные экситоны в спектре оптического поглощения оксида цинка, легированного марганцем

2019 ◽  
Vol 61 (5) ◽  
pp. 817
Author(s):  
В.И. Соколов ◽  
Н.Б. Груздев ◽  
В.А. Важенин ◽  
А.В. Фокин ◽  
А.В. Дружинин
Keyword(s):  
Zinc Oxide ◽  
Charge Transfer ◽  
Absorption Band ◽  
Optical Absorption ◽  
Absorption Spectra ◽  
Polarized Light ◽  
Threshold Energy ◽  
Impurity Absorption ◽  
Charge Transfer Transitions ◽  
Long Time

AbstractThe results of the study of optical absorption and EPR signals of single crystals of zinc oxide doped with manganese are presented. A broad impurity absorption band with the threshold energy about 2.1 eV, which was treated as a result of charge transfer transitions, has been observed for a long time in ZnO : Mn absorption spectra. In absorption spectra of a polarized light at 4.2 and 77.3 K, we first detected several lines of different intensity in a 1.877–1.936 eV range of energies of the light quanta. The observed lines are attributed to a donor exciton [( d ^5 + h ) e ] that emerges as a result of the Coulomb binding a free s electron and a hole, which is localized on p – d hybridized states. The EPR spectra of Mn^2+ ion signals, when corresponding to the impurity absorption band exposed to light, are found to be not photosensitive. The obtained results indicate that the ZnO : Mn impurity absorption is due to transitions from antibonding p – d hybridized DBH states to the conduction band.

scholarly journals Оптическая спектроскопия и сверхпроводимость купратов (О б з о р)

2019 ◽  
Vol 61 (5) ◽  
pp. 809
Author(s):  
А.С. Москвин
Keyword(s):  
Optical Properties ◽  
Charge Transfer ◽  
High Temperature ◽  
Absorption Band ◽  
High Temperature Superconductors ◽  
Electron Hole ◽  
Electric Polarizability ◽  
Fundamental Absorption Band ◽  
Charge Transfer Transitions ◽  
Low Dimensional

AbstractThe optical properties of low-dimensional dielectric cuprates, including parent systems for high-temperature superconductors, such as La_2CuO_4, Sr_2CuO_2Cl_2, and YBa_2Cu_3O_6 are briefly reviewed. The main focus is on the d – d and p – d charge transfer transitions, which determine the fundamental absorption band. The analysis of optical properties shows the instability of parent cuprates against the d – d charge transfer with the formation of metastable electron–hole (EH) dimers of the Cu^1+–Cu^3+-type pairs coupled by the two-particle transfer and characterized by the giant electric polarizability. The formation of a system of stable EH dimers upon nonisovalent substitution determines the unconventional properties of the pseudogap and superconducting phases of doped cuprates.

Charge-transfer and intraligand electronic spectra of bipyridyl complexes of iron, ruthenium, and osmium. II. Tervalent complexes

1971 ◽  
Vol 24 (2) ◽  
pp. 275 ◽  
Author(s):  
GM Bryant ◽  
JE Fergusson
Keyword(s):  
Charge Transfer ◽  
Metal Ions ◽  
Electronic Spectra ◽  
Metal Reduction ◽  
Spectral Bands ◽  
Charge Transfer Transitions ◽  
Halide Ligand ◽  
Halide Ligands

The electronic spectra of a series of six-coordinate octahedral tris-, bis-, and mono-bipyridyl complexes of tervalent iron, ruthenium, and osmium have been recorded and spectral bands assigned to intraligand and charge-transfer transitions. The tris-bipyridyl complexes and bis- and mono-bipyridyl complexes containing other ligands such as pyridine and cyanide show a metal reduction transition π(bipy) → t2(metal). Bipyridyl complexes of osmium containing halide ligands show a similar transition, but for the corresponding complexes of iron and ruthenium the metal reduction transition is now X(halogen) → t2(metal), the electron originating on the halide ligand. Bipyridyl-acetylacetonate complexes have more complicated spectra. Trends in the spectral bands, for all the complexes, indicate that of the three metal ions ruthenium probably forms the strongest M→L π-interaction.

Second hyperpolarizability of multimetallocenes [Cp–Mn–Cp] of Be, Mg and Ca

2015 ◽  
Vol 14 (01) ◽  
pp. 1550002 ◽  
Author(s):  
Kaushik Hatua ◽  
Prasanta K. Nandi
Keyword(s):  
Charge Transfer ◽  
Theoretical Study ◽  
Small Variation ◽  
Cooperative Effect ◽  
Second Hyperpolarizability ◽  
Nlo Property ◽  
Metal Atoms ◽  
Bonding Interaction ◽  
Charge Transfer Transitions ◽  
The Difference

Multimetallocene complexes ( Cp – M n– Cp ) of Be , Mg and Ca have been considered for the theoretical study of static second hyperpolarizability using a number of DFT functionals. Owing to the cooperative effect in bonding, beryllium forms multiberyllocene complexes ( Cp – Be n– Cp ) which have sufficient thermal stability with respect to dissociation into neutral fragments up to n = 10. On the other hand, multimetallocene complexes of Mg and Ca are found to be stable for n ≤ 5 which may be due to the weaker covalent bonding interaction between the larger metal atoms. The rather small variation of linear and cubic polarizabilities of Cp – Be n– Cp complexes beyond n = 5 arises from the rather weaker charge transfer transitions. The difference in NLO property among the investigated metal complexes arises from the extent of charge transfer from the terminal metal atoms and the distance between them. The charge transfer at longer distances in the ground state of Mg and Ca complexes leads to more intense electronic transition — the spectroscopic parameters of which strongly favors the enhancement of second hyperpolarizability.

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