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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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TL;DR: In this paper, the real and imaginary parts of the dielectric constant of Rb and Cs at room temperature in the frequency range 0.5-4.0 eV were measured by multiple reflection at metal-silica interfaces.
Abstract: Measurements are reported for ${\ensuremath{\epsilon}}_{1}$ and ${\ensuremath{\epsilon}}_{2}$, the real and imaginary parts of the dielectric constant, of Rb and Cs at room temperature in the frequency range 0.5-4.0 eV. The experiments were performed by multiple reflection at metal-silica interfaces employing the technique used earlier on Na and K. The optical absorption of Rb shows structure which can be attributed to conventional interband transitions within the nearly free-electron model. The optical absorption of Cs also shows structure, but the threshold occurs at a lower frequency than that predicted by the nearly free-electron model. Both metals show a leveling off and a perceptible rise in the absorption at the high-frequency end of the range. The possibility of absorption due to many-body effects or transitions to $d$ bands above the Fermi level is discussed. The results for ${\ensuremath{\epsilon}}_{1}$ are used to deduce values for the infrared optical masses which are found to be 1.16 m for Rb and 1.19 m for Cs.

75 citations

Journal ArticleDOI
TL;DR: In this paper, the collision-induced absorption and emission coefficients for electric-dipole forbidden atomic transitions are calculated for weak radiation fields and compared to measurements for spherically symmetric perturbation.
Abstract: The collision-induced absorption and emission coefficients for electric-dipole forbidden atomic transitions are calculated for weak radiation fields. The approximations used are valid for $\ensuremath{\hbar}\ensuremath{\omega}$ near $\ensuremath{\hbar}{\ensuremath{\omega}}_{0}$, the atomic energy differences. The example case of $S\ensuremath{-}D$ transitions induced by a spherically symmetric perturber (e.g., a noble-gas atom) is treated in detail and compared to measurements. The case of "radiative collisions," in which both colliding atoms change their state, is included in the theory and is also compared to experiment.

74 citations

Journal ArticleDOI
TL;DR: The first terahertz study of the intraexcitonic transition at high excitation densities in quantum wells was performed in this paper, where the authors reported a significant energy shift, broadening, and disappearance of this resonance with increasing density after ultrafast photoexcitation at the near-infrared exciton line.
Abstract: We report the first terahertz study of the intraexcitonic $1s\text{\ensuremath{-}}2p$ transition at high excitation densities in $\mathrm{GaAs}∕{\mathrm{Al}}_{x}{\mathrm{Ga}}_{1\ensuremath{-}x}\mathrm{As}$ quantum wells A strong shift, broadening, and ultimately the disappearance of this resonance occurs with increasing density, after ultrafast photoexcitation at the near-infrared exciton line Densities of excitons and unbound electron-hole pairs are followed quantitatively using a model of the composite terahertz dielectric response Comparison with near-infrared absorption changes reveals a significantly enhanced energy shift and broadening of the intraexcitonic resonance

74 citations

Journal ArticleDOI
TL;DR: In this article, the total energy reflected from crystalline and amorphous silicon illuminated by a femtosecond laser pulse was measured for wavelengths of 0.62 and 0.31 µm.
Abstract: Measurements of the total energy reflected from crystalline and amorphous silicon illuminated by a femtosecond laser pulse are reported, for wavelengths of 0.62 and 0.31 \ensuremath{\mu}m. The results are interpreted by use of a highly nonlinear regime of light propagation in the dense plasma of electrons and holes ($e\ensuremath{-}h$). Densities higher than ${10}^{22}$ ${\mathrm{cm}}^{\ensuremath{-}3}$ are reached. We demonstrate that free-carrier absorption is dominated by $e\ensuremath{-}h$ collisions.

74 citations

Journal ArticleDOI
TL;DR: In this article, the authors measured the absorption coefficient of CdS in polarized light at wavelengths near 5000 A. The results showed that the conduction band minimum and valence band maximum occur at the center of the Brillouin zone.
Abstract: Measurements of the absorption coefficient between 10 and 300 ${\mathrm{cm}}^{\ensuremath{-}1}$ have been made with crystals of CdS in polarized light between 20 and 300\ifmmode^\circ\else\textdegree\fi{}K, at wavelengths near 5000 A. Analysis of the results at various temperatures near 70\ifmmode^\circ\else\textdegree\fi{}K shows that the absorption is in agreement with that calculated for a process involving the simultaneous creation of an exciton and the absorption of a phonon, both particles having a small wave vector. This agreement is strong evidence that the conduction band minimum and the valence band maximum in CdS both occur at the center of the Brillouin zone.

74 citations


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