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Absorption (logic)

About: Absorption (logic) is a research topic. Over the lifetime, 5733 publications have been published within this topic receiving 236302 citations.


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Journal ArticleDOI
TL;DR: In this article, the partial density of state obtained from local density approximation (LDA) and U$ calculations were compared with the experimental results, and the LDA+U$ approach was suitable to correct LDA self-interaction error of the cation $d$ states.
Abstract: $\mathrm{O}\phantom{\rule{0.3em}{0ex}}1s$ absorption spectroscopy (XAS) and $\mathrm{O}\phantom{\rule{0.3em}{0ex}}K\ensuremath{\alpha}$ emission spectroscopy (XES) were performed to study the electronic structure of nanostructured ZnO. The band gap is determined by the combined absorption-emission spectrum. Resonantly excited XES spectra showing an energy dependence in the spectral shape reveal the selected excitations to the different $\mathrm{Zn}\phantom{\rule{0.3em}{0ex}}3d$, $4s$, and $4p$ states in hybridization with $\mathrm{O}\phantom{\rule{0.3em}{0ex}}2p$ states. The partial density of state obtained from local density approximation (LDA) and $\mathrm{LDA}+U$ calculations are compared with the experimental results. The $\mathrm{LDA}+U$ approach is suitable to correct LDA self-interaction error of the cation $d$ states. The atomic eigenstates of $3d$ in zinc and $2p$ in oxygen are energetically close, which induces the strong interaction between $\mathrm{Zn}\phantom{\rule{0.3em}{0ex}}3d$ and $\mathrm{O}\phantom{\rule{0.3em}{0ex}}2p$ states. This anomalous valence band cation-$d$--anion-$p$ hybridization is verified by taking into account the strong localization of the $\mathrm{Zn}\phantom{\rule{0.3em}{0ex}}3d$ states.

189 citations

Journal ArticleDOI
TL;DR: Within the superconducting composition range, ${R}_{H}$ exhibits characteristic temperature dependence and the optical reflectance spectrum changes from that of a semiconductor at $x=0$ to a typical metallic one characterized by the Drude model for $xg0.1$, indicating the development of itinerant holes in the Cu-O planes.
Abstract: The low-field Hall coefficient ${R}_{H}$, optical reflectance and transmittance of the ${\mathrm{La}}_{2\ensuremath{-}x}{\mathrm{Sr}}_{x}\mathrm{Cu}{\mathrm{O}}_{4}$ system with various Sr concentrations from $x=0 \mathrm{to} 0.36$ are systematically studied using single-crystal thin films epitaxially grown on (100) face SrTi${\mathrm{O}}_{3}$ substrates with the $c$ axis normal to the film surface. For the $x$ range measured, ${R}_{H}$ is positive and decreases more rapidly than that expected from the Sr concentration but more slowly than reported earlier for polycrystalline specimens, indicating anisotropy of ${R}_{H}$. Furthermore, the $x$ dependence indicates deviation from that expected from a simple band model. Within the superconducting composition range, ${R}_{H}$ exhibits characteristic temperature dependence. The optical reflectance spectrum changes from that of a semiconductor at $x=0$ to a typical metallic one characterized by the Drude model for $xg0.1$, indicating the development of itinerant holes in the Cu-O planes. In the optical transmission spectra, an anomalous absorption band is seen in addition to the fundamental absorption corresponding to an energy gap of about 2 eV. This band, which develops with Sr doping, implies an enhancement of the density of states near the Fermi level. Taking these observations into account, the normal-state transport properties are explained with a qualitative consistence.

188 citations

Journal ArticleDOI
TL;DR: In this article, a method of x-ray absorption spectroscopy (XAS) that is bulk sensitive, like traditional fluorescence yield measurements, but is not affected by self-absorption or saturation effects is presented.
Abstract: We demonstrate a method of x-ray absorption spectroscopy (XAS) that is bulk sensitive, like traditional fluorescence yield measurements, but is not affected by self-absorption or saturation effects. This measure of XAS is achieved by scanning the incident photon energy through an absorption edge and using an energy-sensitive photon detector to measure the partial fluorescence yield (PFY). The x-ray emission from any element or core-hole excitation that is not resonant with the absorption edge under investigation is selected from the PFY. It is found that the inverse of this PFY spectrum, which we term inverse partial fluorescence yield (IPFY), is linearly proportional to the x-ray absorption cross-section without any corrections due to saturation or self-absorption effects. We demonstrate this technique on the Cu ${L}_{2,3}$ and Nd ${M}_{4,5}$ absorption edges of the high-${T}_{c}$ cuprate ${\mathrm{La}}_{1.475}{\mathrm{Nd}}_{0.4}{\mathrm{Sr}}_{0.125}{\mathrm{CuO}}_{4}$ by measuring the O ${K}_{\ensuremath{\alpha}}$ PFY and comparing the total electron yield, total fluorescence yield, and IPFY spectra.

188 citations

Journal ArticleDOI
TL;DR: It is found that the optical properties of carbon nanotubes reflect remarkably strong effects of exciton- phonon coupling, and a significant fraction of the spectral weight of the absorption peak is transferred to a distinct exciton+phonon sideband, which is peaked at around 200 meV above the main absorption peak.
Abstract: We find that the optical properties of carbon nanotubes reflect remarkably strong effects of exciton-phonon coupling. Tight-binding calculations show that a significant fraction of the spectral weight of the absorption peak is transferred to a distinct $\mathrm{\text{exciton}}+\mathrm{\text{phonon}}$ sideband, which is peaked at around 200 meV above the main absorption peak. This sideband provides a distinctive signature of the excitonic character of the optical transition. The exciton-phonon coupling is reflected in a dynamical structural distortion, which contributes a binding energy of up to 100 meV. The distortion is surprisingly long ranged, and is strongly dependent on chirality.

188 citations

Journal ArticleDOI
TL;DR: In this paper, the authors presented two different designs of robust, easily manufactured metamaterial-based films of subwavelength thickness capable of full absorption of incident terahertz radiation at certain frequencies.
Abstract: We present two different designs of robust, easily manufactured metamaterial-based films of subwavelength thickness capable of full absorption of incident terahertz radiation at certain frequencies. Both designs allow a choice between the total absorption of all polarizations or only one linear polarization while the other polarization is reflected. Even if the films are optimized for normal incidence, the absorption remains greater than 99% for angles up to $\ensuremath{\sim}35\ifmmode^\circ\else\textdegree\fi{}$ in the TE and up to $\ensuremath{\sim}65\ifmmode^\circ\else\textdegree\fi{}$ in the TM case. In the first design, the maximum absorption frequency shifts considerably with angle, and in the second design it is independent of angle.

187 citations


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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
2021290
2020249
2019220
2018230
2017162
2016163