Absorption (logic)

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

Pure spin current from one-photon absorption of linearly polarized light in noncentrosymmetric semiconductors.

Abstract: We show that one-photon absorption of linearly polarized light should produce pure spin currents in noncentrosymmetric semiconductors, including even bulk GaAs. We present $14\ifmmode\times\else\texttimes\fi{}14$ $\mathbf{k}\ifmmode\cdot\else\textperiodcentered\fi{}\mathbf{p}$ model calculations of the effect in GaAs, including strain, and pseudopotential calculations of the effect in wurtzite CdSe.

Effect of Uniaxial and Hydrostatic Strain on the Optical Constants and the Electronic Structure of Copper

Abstract: The linear response of the optical constants of Cu to a general strain is presented for the range $1.5\ensuremath{\le}\ensuremath{\hbar}\ensuremath{\omega}\ensuremath{\le}5.5$ eV. The transitions ${X}_{5}\ensuremath{\rightarrow}{{X}_{4}}^{\ensuremath{'}}$ at 4.0 eV and ${E}_{F}\ensuremath{\rightarrow}{L}_{1}$ at 4.15 eV are identified. The deformation potentials $\frac{\ensuremath{\partial}({E}_{F}\ensuremath{-}{{L}_{3}}^{\mathrm{upper}})}{\ensuremath{\partial}e}=\ensuremath{-}(1.1\ifmmode\pm\else\textpm\fi{}0.1)$ eV and $\frac{\ensuremath{\partial}({L}_{1}\ensuremath{-}{E}_{F})}{\ensuremath{\partial}e}=\ensuremath{-}(9.6\ifmmode\pm\else\textpm\fi{}1.5)$ eV with $e=\frac{\ensuremath{\Delta}V}{V}$, and $\frac{\ensuremath{\partial}{L}_{1}}{\ensuremath{\partial}{e}_{\mathrm{yz}}}=\ensuremath{-}(72\ifmmode\pm\else\textpm\fi{}12)$ eV with ${e}_{\mathrm{xy}}={e}_{\mathrm{yz}}={e}_{\mathrm{zx}}$, ${e}_{\mathrm{xx}}={e}_{\mathrm{yy}}={e}_{\mathrm{zz}}=0$ for k\ensuremath{\parallel}[111] are evaluated from the measurements. They are used to derive the volume coefficients of the Fermi energy, $\frac{\ensuremath{\partial}(\mathrm{ln}{E}_{F})}{\ensuremath{\partial}e}=\ensuremath{-}1.1\ifmmode\pm\else\textpm\fi{}0.3$, and of the position of the $d$ bands, $\frac{\ensuremath{\partial}(\mathrm{ln}{E}_{d})}{\ensuremath{\partial}e}=\ensuremath{-}1.2\ifmmode\pm\else\textpm\fi{}0.5$, with respect to ${\ensuremath{\Gamma}}_{1}$. The measurements are consistent with the assumption that direct interband transitions dominate the absorption above 2 eV.

X-ray spectroscopic study of the electronic structure of CuCrO 2

Abstract: The electronic structure of the $p$-type transparent conducting oxide ${\text{CuCrO}}_{2}$ has been studied by x-ray photoemission, x-ray absorption, and x-ray emission spectroscopies. The upper part of the valence band derives mainly from $\text{Cu}\text{ }3d$ and $\text{Cr}\text{ }3d$ states while the lower valence-band states are of dominant $\text{O}\text{ }2p$ atomic character, but with pronounced mutual hybridization among $\text{Cu}\text{ }3d$, $\text{Cr}\text{ }3d$, and $\text{O}\text{ }2p$ states. Site specific electronic excitations have been studied by resonant inelastic x-ray scattering at the $\text{Cu}\text{ }L$ and $\text{Cr}\text{ }L$ edges. Inelastic loss at the $\text{Cu}\text{ }L$ edge is dominated by on-site interband excitations similar to those found in ${\text{Cu}}_{2}\text{O}$, while at the $\text{Cr}\text{ }L$ edge localized excitations arising from ligand field splitting of the $\text{Cr}\text{ }3d$ levels are observed. Mg doping on the Cr sites in ${\text{CuCrO}}_{2}$ is shown to lead to a pronounced shift in the Fermi level toward the edge of the valence band. The experimental data are compared to electronic structure calculations on ${\text{CuCrO}}_{2}$ carried out using density-functional methods corrected for onsite Coulomb repulsion.

Study of Ionization-Induced Radiation Damage in MgO

Abstract: A study of the 2.3-eV absorption band in MgO crystals irradiated with electrons and gamma rays at 7, 80, and 305\ifmmode^\circ\else\textdegree\fi{}K has been made. This broad band, which has been designated as ${V}_{1}$, has a half-width of 0.96 eV at 5 and 78\ifmmode^\circ\else\textdegree\fi{}K and could be optically bleached even at liquid-helium temperature. When specimens were bleached with polarized light, it was found that there was no dichroism in any of the $〈100〉$, $〈110〉$, or $〈111〉$ directions at 5\ifmmode^\circ\else\textdegree\fi{}K. The colorability of the crystals was strongly dependent on their thermal treatment. The concentration of centers responsible for the 2.3-eV absorption could be enhanced by quenching the crystals from high temperature prior to irradiation and could be suppressed by slow cooling of the specimens to room temperature. The effects of these heat treatments were found to be reversible. The presence of certain impurities in the crystals was observed to suppress the 2.3-eV coloration, but no correlation between the ${\mathrm{Fe}}^{3+}$ concentration or the total Fe concentration and the maximum coloration in a quenched crystal was observed. The afterglow luminescence was also surveyed in the energy range 1.3-5.0 eV.

Sulfur K-Edge X-Ray-Absorption Study of the Charge Transfer upon Lithium Intercalation into Titanium Disulfide.

Abstract: Sulfur K-edge x-ray-absorption spectra have been recorded for lithium intercalated titanium disulfides ${\mathrm{Li}}_{x}{\mathrm{TiS}}_{2}$. The near-edge features up to 30 eV above threshold are interpreted in the framework of full multiple-scattering theory. We show that the electrons transferred from intercalated lithium atoms are not only located on Ti $3d$ orbitals, as previously assumed, but also on the S $3p$ states. For comparison, we present the S $p$-projected density of states derived from linear muffin-tin-orbital band structure calculations. An overall agreement between measurement and theory is very well achieved.