Topic
Absorption (electromagnetic radiation)
About: Absorption (electromagnetic radiation) is a research topic. Over the lifetime, 76674 publications have been published within this topic receiving 1381221 citations.
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TL;DR: In this paper, the primary basis for the detection of stress conditions in a crop or other plant community by aerial remote sensors often, however, is not a change in the reflectance characteristics of individual leaves, but a reduction in the total leaf area exposed to the sensors.
1,143 citations
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TL;DR: In this article, a detailed analysis of the laser properties of Ti:Al2O3 is presented, including absorption and fluorescence spectra and lifetime as a function of temperature.
Abstract: Spectroscopic measurements and laser performance of Ti:Al2O3 are discussed in detail. Data on absorption and fluorescence spectra and fluorescence lifetime as a function of temperature are presented. Laser characteristics observed with pulsed-dye-laser, frequency-doubled Nd:YAG-laser, and argon-ion-laser pumping are covered and show that nearly quantum-limited conversion of pump radiation can be achieved, along with tuning over the wavelength range 660–986 nm.
1,131 citations
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TL;DR: The synthesized C, N, and S-doped titania nanomaterials show an increased electron density of states above the valence band of TiO2, which explains the red-shifted light absorption of these potential photocatalysts and simultaneously suggests a lowered potential as photooxidants compared to Degussa P25 TiO 2.
Abstract: The origin of the visible-light absorption of main-group element (C, N, S) doped TiO2 nanostructures is investigated via diffuse reflectance and valence band X-ray photoelectron spectroscopy. The synthesized C-, N-, and S-doped titania nanomaterials show an increased electron density of states above the valence band of TiO2, which explains the red-shifted light absorption of these potential photocatalysts and simultaneously suggests a lowered potential as photooxidants compared to Degussa P25 TiO2.
1,095 citations
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TL;DR: In this paper, a survey is given of recent results concerning particle-size dependences of the optical plasma resonance absorption and of the FIR absorption of small noble metal particles, and it is shown that the spectra are strongly changed if the particles of a sample interact with each other.
1,093 citations
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TL;DR: In this paper, three forms of the Kramers-Kronig type of dispersion equation are presented, and the absorption coefficient has a linear dependence upon frequency for frequencies above a certain characteristic value, chosen low enough to be outside the range of measurement.
Abstract: Although the attenuation of body waves in an infinite medium has often been considered, little emphasis is usually given to the attendant dispersion, which is a necessary consequence of the medium absorption and is determined unambiguously by it. Dispersion equations are obtained from the application of an integral transform in the frequency domain. Such relations are of the Kramers-Kronig type, relating the dispersive part of the index of refraction of the medium to the absorptive part by means of an integral over the entire frequency range. They are a consequence of the principle of causality and follow without recourse to a specific wave equation. In particular, our results are consistent with and presume linearity for the wave motion. Three forms of the dispersion equation are exhibited. In all cases, the absorption coefficient has a linear dependence upon frequency for frequencies above a certain characteristic value—chosen low enough to be outside the range of measurement. However, it is necessary in all cases to introduce a low-frequency, nonzero cutoff for the absorption, which can in principle be taken arbitrarily small. Group and phase velocities are determined as functions of the medium Q and a characteristic velocity, which for small absorption can be related to the measured signal velocity. Seismic phenomena occur in materials where the absorption is small, Q≥30, so that the corresponding dispersion presumably will be difficult to measure in the earth. For appropriate laboratory materials the effect can be significant.
1,080 citations