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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, absolute absorption cross sections of O3 were measured in the 230 −850 nm region at five different temperatures (203 −293 K) using a Fourier-transform spectrometer, at a spectral resolution of 5.0 −1.
Abstract: Absolute absorption cross sections of O3 were measured in the 230–850 nm (11765–43478 cm−1) region at five different temperatures (203–293 K) using a Fourier-transform spectrometer, at a spectral resolution of 5.0 cm−1 (corresponding to about 0.027 nm at 230 nm and to about 0.36 nm at 850 nm). The spectral accuracy of the data is better than 0.1 cm−1 — about 0.5 pm at 230 nm and about 7.2 pm at 850 nm — validated by recording of I2 absorption spectra in the visible using the same experimental set-up. O3 absorption spectra at different concentrations were recorded at five different sample temperatures in the range 203–293 K, and at each temperature at two total pressures (100 and 1000 mbar) using O2/N2 mixtures as buffer gas. Within the limits of experimental uncertainties, no influence of total pressure on the O3 spectrum was observed in the entire spectral region, as expected from the short lifetimes of the upper electronic states of O3. The temperature dependence of the O3 absorption cross sections is particularly strong in the Huggins bands between 310 and 380 nm, as observed in previous studies. An empirical formula is used to model the temperature dependence of the O3 absorption cross sections between 236 and 362 nm, a spectral region that is particularly important for atmospheric remote-sensing and for photochemical modelling.

206 citations

Journal ArticleDOI
TL;DR: In this article, the filling-in of Fraunhofer and gas absorption features, resulting from Rotational Raman scattering (RRS), explains to high accuracy the Ring effect.
Abstract: One significant limitation to the accuracy of the remote sensing of trace gas constituents in the atmosphere, using UV-visible spectroscopy and scattered sunlight, has often been a reliable knowledge of the so-called Ring effect. In this study it is demonstrated that the filling-in of Fraunhofer and gas absorption features, resulting from Rotational Raman scattering (RRS), explains to high accuracy the Ring effect. A radiative transfer model has been adapted to include RRS and carefully validated by comparison with Ring effect data by other models and from ground-based and satellite data. The analysis of the principle components of the simulated Ring spectra enabled the Fraunhofer and gas absorption filling-in to be separated. This yields a simple, and therefore computational fast, parameterization of the Ring effect suitable for trace gas retrievals. This approach was tested for the retrieval of NO 2 which is considered to be a worst case with respect to absorption feature filling-in for a trace gas retrieved from scattered light. Analysis of the errors in the vertical column of NO 2 derived using differential optical absorption spectroscopy (DOAS) technique indicate that they are dependent on the amount of NO 2 present in the atmosphere when regarding the experimental Ring spectra. This implies that calculated Ring spectra may be superior for DOAS retrievals, compared to the experimentally determined Ring spectra.

206 citations

Journal ArticleDOI
TL;DR: In this paper, the authors presented a novel thin-walled energy absorption device known as the origami crash box, which is made from a thinwalled tube of square cross section whose surface is prefolded according to a developable origami pattern.
Abstract: Thin-walled tubes subjected to axial crushing have been extensively employed as energy absorption devices in transport vehicles. Conventionally, they have a square or rectangular section, either straight or tapered. Dents are sometimes added to the surface in order to reduce the initial buckling force. This paper presents a novel thin-walled energy absorption device known as the origami crash box that is made from a thin-walled tube of square cross section whose surface is prefolded according to a developable origami pattern. The prefolded surface serves both as a type of geometric imperfection to lower the initial buckling force and as a mode inducer to trigger a collapse mode that is more efficient in terms of energy absorption. It has been found out from quasi-static numerical simulation that a new collapse mode referred to as the completed diamond mode, which features doubled traveling plastic hinge lines compared with those in conventional square tubes, can be triggered, leading to higher energy absorption and lower peak force than those of conventional ones of identical weight. A parametric study indicates that for a wide range of geometric parameters the origami crash box exhibits predictable and stable collapse behavior, with an energy absorption increase of 92.1% being achieved in the optimum case. The origami crash box can be stamped out of a thin sheet of material like conventional energy absorption devices without incurring in-plane stretching due to the developable surface of the origami pattern. The manufacturing cost is comparable to that of existing thin-walled crash boxes, but it absorbs a great deal more energy during a collision. [DOI: 10.1115/1.4024405]

206 citations

Journal ArticleDOI
TL;DR: In this article, the photonic crystal geometry is fabricated using a materials-agnostic process called PRINT wherein highly ordered arrays of nanoscale features are readily made in a single processing step over wide areas (∼4 cm2) that is scalable.
Abstract: We report organic solar cells with a photonic crystal nanostructure embossed in the photoactive bulk heterojunction layer, a topography that exhibits a 3-fold enhancement of the absorption in specific regions of the solar spectrum in part through multiple excitation resonances. The photonic crystal geometry is fabricated using a materials-agnostic process called PRINT wherein highly ordered arrays of nanoscale features are readily made in a single processing step over wide areas (∼4 cm2) that is scalable. We show efficiency improvements of ∼70% that result not only from greater absorption, but also from electrical enhancements. The methodology is generally applicable to organic solar cells and the experimental findings reported in our manuscript corroborate theoretical expectations.

206 citations

Journal ArticleDOI
TL;DR: In this article, the self-assembly of g-C3N4 nanotubes by co-polycondensation of urea and oxamide with their similar structure and reactivity to optimize the textural and electronic properties is reported.
Abstract: Melon-based carbon nitride (g-C3N4) is a promising metal-free and sustainable material for photocatalytic water splitting In principle, pristine carbon nitride only exhibits moderate activity due to insufficient visible light absorption and fast charge recombination Enhancement of the solar-to-energy conversion efficiency of g-C3N4 depends on the rational design of its morphology and electronic structure Herein, we report the self-assembly of g-C3N4 nanotubes by co-polycondensation of urea and oxamide with their similar structure and reactivity to optimize the textural and electronic properties Unlike pristine g-C3N4, the obtained copolymers exhibit clear optical absorption above 465 nm, which is ascribed to the n → π* electron transition involving lone pairs of the edge nitrogen atoms of the heptazine units Besides, the charge carrier mobility was also optimized in the spatially separated nanotube structure, which contributes to the generation of more hot electrons The optimized copolymers show dramatically enhanced H2 evolution activities especially with green light The achieved apparent quantum yield (AQY) of optimal CN-OA-005 for H2 evolution with a green LED (λ = 525 nm) reaches 13%, which is about 10 times higher than that of pure CN with state-of-the-art activity in this wavelength region

205 citations


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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
2022185
20213,106
20202,866
20192,953
20182,876
20172,679