Assignment of charge transfer absorption band in optical absorption spectra of the adsorbate–silver colloid system

The article simulates the optical absorption spectra (OAS) of endohedral complexes Er2C2 @ C90 based on isomers No. 44 (C2) No. 21 (C1) of fullerene C90. For this purpose, the energy spectra of the indicated isomers have been calculated. The calculation was carried out within the framework of two models. Within the framework of the first model, which is traditional, only hops of π-electrons from site to site were taken into account (the integral of hopping to the nearest sites B ~ -2.6 eV). Within the framework of the second model, developed in a series of our works [1-5], in addition to hopping from site to site (the integral of hopping to the nearest sites B ~ -1.0 eV), the intrasite Coulomb interaction (ICCI) of π-electrons was also taken into account (the integral of the Coulomb interaction U ~ 7.0 eV). Comparison of the OSS curves obtained by us with the experimental data [5] convincingly indicates that the second model adequately describes the OSS of the endohedral Er2C2 @ C90 complexes based on the investigated isomers. The magnitude of charge transfer from the Er2C2 system to the fullerene shell turned out to be -4e.

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Локализованные экситоны в спектре оптического поглощения оксида цинка, легированного марганцем

Физика твердого тела ◽

10.21883/ftt.2019.05.47573.09f ◽

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.

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Theoretical Insight into the Spectral Characteristics of Fe(II)-Based Complexes for Dye-Sensitized Solar Cells—Part I: Polypyridyl Ancillary Ligands

International Journal of Photoenergy ◽

10.1155/2011/316952 ◽

2011 ◽

Vol 2011 ◽

pp. 1-11 ◽

Cited By ~ 1

Author(s):

Xiaoqing Lu ◽

Shuxian Wei ◽

Chi-Man Lawrence Wu ◽

Ning Ding ◽

Shaoren Li ◽

...

Keyword(s):

Solar Cells ◽

Charge Transfer ◽

Optical Absorption ◽

Absorption Spectra ◽

Dye Sensitized Solar Cells ◽

Optical Absorption Spectra ◽

Ancillary Ligands ◽

Dye Sensitized ◽

Ligand Charge Transfer ◽

Sensitized Solar Cells

The design of light-absorbent dyes with cheaper, safer, and more sustainable materials is one of the key issues for the future development of dye-sensitized solar cells (DSSCs). We report herein a theoretical investigation on a series of polypyridyl Fe(II)-based complexes of FeL2(SCN)2, [FeL3]2+, [FeL′(SCN)3]-, [FeL′2]2+, and FeL′′(SCN)2(L = 2,2′-bipyridyl-4,4′-dicarboxylic acid, L′ = 2,2′,2″-terpyridyl-4,4′,4″-tricarboxylic acid, L″= 4,4‴-dimethyl-2,2′ : 6′,2″ :6″,2‴-quaterpyridyl-4′,4″-biscarboxylic acid) by density functional theory (DFT) and time-dependent DFT (TD-DFT). Molecular geometries, electronic structures, and optical absorption spectra are predicted in both the gas phase and methyl cyanide (MeCN) solution. Our results show that polypyridyl Fe(II)-based complexes display multitransition characters of Fe → polypyridine metal-to-ligand charge transfer and ligand-to-ligand charge transfer in the range of 350–800 nm. Structural optimizations by choosing different polypyridyl ancillary ligands lead to alterations of the molecular orbital energies, oscillator strength, and spectral response range. Compared with Ru(II) sensitizers, Fe(II)-based complexes show similar characteristics and improving trend of optical absorption spectra along with the introduction of different polypyridyl ancillary ligands.

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On the Origin of EL2 Intracenter Absorption Band in GaAs

MRS Proceedings ◽

10.1557/proc-104-405 ◽

1987 ◽

Vol 104 ◽

Cited By ~ 4

Author(s):

M. Skowronski

Keyword(s):

Absorption Band ◽

Optical Absorption ◽

Absorption Spectra ◽

Conduction Band ◽

Metastable State ◽

Uniaxial Stress ◽

Alternative Interpretation ◽

Optical Absorption Spectra ◽

Wide Absorption Band ◽

Dx Center

ABSTRACTAn alternative interpretation of optical absorption spectra due to intracenter transition within EL2 defect in GaAs is provided. The arguments are presented that states originating from the L-valley of the conduction band can account for the presence of the wide absorption band, the no-phonon line and the observed uniaxial stress splittings. Using the analogy to the DX center, this model presents an explanation for the existence of the metastable state of EL2.

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