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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 article, the infrared spectra of cotton cellulose were used to follow changes in hydrogen bonding by the classical method of observing the exact wavelengths of the O-H stretching vibrations, and degree of crystallinity can be measured quantitatively by use of ratios of intensities of preselected absorption bands.
Abstract: The KBr technique to obtain spectra of cotton cellulose has been applied satisfactorily to an investigation of physical and crystalline modifications and to changes resulting from oxidation. Several experiments to illustrate applications are described. The potential applications to investigations suggested in the literature are reviewed.It has been shown that infrared absorption spectra of cotton cellulose can be used to follow changes in hydrogen bonding by the classical method of observing the exact wavelengths of the O-H stretching vibrations. Degree of crystallinity can be measured quantitatively by use of ratios of intensities of preselected absorption bands. Oxidation changes can be followed only where such processes result in the formation of C = O groups per se in the oxidized cotton.
295 citations
295 citations
TL;DR: In this article, the luminescence energy transfer between small noble metal particles and lanthanide(III) ions was studied, and it was shown that the observed enhancement is due to a classical energy transfer, and not to a plasmonic field enhancement effect.
Abstract: With the technique of synchrotron X-ray activation, molecule-like, non-plasmonic gold and silver particles in soda-lime silicate glasses can be generated. The luminescence energy transfer between these species and Ianthanide(III) ions is studied. As a result, a significant lanthanide luminescence enhancement by a factor of up to 250 under non-resonant UV excitation is observed. The absence of a distinct gold and silver plasmon resonance absorption, respectively, the missing nanoparticle signals in previous SAXS and TEM experiments, the unaltered luminescence lifetime of the lanthanide ions compared to the non-enhanced case, and an excitation maximum at 300―350 nm (equivalent to the absorption range of small noble metal particles) indicate unambiguously that the observed enhancement is due to a classical energy transfer between small noble metal particles and lanthanide ions, and not to a plasmonic field enhancement effect. It is proposed that very small, molecule-like noble metal particles (such as dimers, trimers, and tetramers) first absorb the excitation light, undergo a singlet-triplet intersystem crossing, and finally transfer the energy to an excited multiplet state of adjacent lanthanide(III) ions. X-ray lithographic microstructuring and excitation with a commercial UV LED show the potential of the activated glass samples as bright light-emitting devices with tunable emission colors.
295 citations
TL;DR: In this article, a combination of Ag nanomaterials of different shapes, including nanoparticles and nanoprisms, is proposed for this purpose, and a wide-band absorption improvement is demonstrated and the short-circuit photocurrent density improves by 17.91%.
Abstract: It is been widely reported that plasmonic effects in metallic nanomaterials can enhance light trapping in organix solar cells (OSCs). However, typical nanoparticles (NP) of high quality (i.e., mono-dispersive) only possess a single resonant absorption peak, which inevitably limits the power conversion efficiency (PCE) enhancement to a narrow spectral range. Broadband plasmonic absorption is obviously highly desirable. In this paper, a combination of Ag nanomaterials of different shapes, including nanoparticles and nanoprisms, is proposed for this purpose. The nanomaterials are synthesized using a simple wet chemical method. Theoretical and experimental studies show that the origin of the observed PCE enhancement is the simultaneous excitation of many plasmonic low- and high-order resonances modes, which are material-, shape-, size-, and polarization-dependent. Particularly for the Ag nanoprisms studied here, the high-order resonances result in higher contribution than low-order resonances to the absorption enhancement of OSCs through an improved overlap with the active material absorption spectrum. With the incorporation of the mixed nanomaterials into the active layer, a wide-band absorption improvement is demonstrated and the short-circuit photocurrent density (Jsc) improves by 17.91%. Finally, PCE is enhanced by 19.44% as compared to pre-optimized control OSCs. These results suggest a new approach to achieve higher overall enhancement through improving broadband absorption.
295 citations
TL;DR: In this paper, the impact of controlled nanopatterning on the Ag back contact of an n-i-p a-Si:H solar cell was investigated experimentally and through electromagnetic simulation.
Abstract: The impact of controlled nanopatterning on the Ag back contact of an n-i-p a-Si:H solar cell was investigated experimentally and through electromagnetic simulation. Compared to a similar reference cell with a flat back contact, we demonstrate an efficiency increase from 4.5% to 6.2%, with a 26% increase in short circuit current density. Spectral response measurements show the majority of the improvement between 600 and 800 nm, with no reduction in photocurrent at wavelengths shorter than 600 nm. Optimization of the pattern aspect ratio using electromagnetic simulation predicts absorption enhancements over 50% at 660 nm.
294 citations