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.

Chemical approaches to artificial photosynthesis

Abstract: The goal of artificial photosynthesis is to use the energy of the sun to make high-energy chemicals for energy production. One approach, described here, is to use light absorption and excited-state electron transfer to create oxidative and reductive equivalents for driving relevant fuel-forming half-reactions such as the oxidation of water to O2 and its reduction to H2. In this “integrated modular assembly” approach, separate components for light absorption, energy transfer, and long-range electron transfer by use of free-energy gradients are integrated with oxidative and reductive catalysts into single molecular assemblies or on separate electrodes in photelectrochemical cells. Derivatized porphyrins and metalloporphyrins and metal polypyridyl complexes have been most commonly used in these assemblies, with the latter the focus of the current account. The underlying physical principleslight absorption, energy transfer, radiative and nonradiative excited-state decay, electron transfer, proton-coupled elec...

Nanostructured materials for photon detection

Abstract: The detection of photons underpins imaging, spectroscopy, fibre-optic communications and time-gated distance measurements. Nanostructured materials are attractive for detection applications because they can be integrated with conventional silicon electronics and flexible, large-area substrates, and can be processed from the solution phase using established techniques such as spin casting, spray coating and layer-by-layer deposition. In addition, their performance has improved rapidly in recent years. Here we review progress in light sensing using nanostructured materials, focusing on solution-processed materials such as colloidal quantum dots and metal nanoparticles. These devices exhibit phenomena such as absorption of ultraviolet light, plasmonic enhancement of absorption, size-based spectral tuning, multiexciton generation, and charge carrier storage in surface and interface traps.

A Guide to the Complete Interpretation of Infrared Spectra of Organic Structures

Abstract: Normal Vibrations and Absorption Regions of CX3. Normal Vibrations and Absorption Regions of CH2X. Normal Vibrations and Absorption Regions of CHX2. Normal Vibrations and Absorption Regions of CHX. Normal Vibrations and Absorption Regions of CX2. Normal Vibrations and Absorption Regions of C(=X)Y. Normal Vibrations and Absorption Regions of Alkenes and Alkynes. Normal Vibrations and Absorption Regions of Nitrogen Compounds. Normal Vibrations and Absorption Regions of Oxy Compounds. Normal Vibrations and Absorption Regions of Sulfur Compounds. Normal Vibrations and Absorption Regions of Ring Structures. Index.

Optical absorption enhancement in amorphous silicon nanowire and nanocone arrays.

Abstract: Hydrogenated amorphous Si (a-Si:H) is an important solar cell material. Here we demonstrate the fabrication of a-Si:H nanowires (NWs) and nanocones (NCs), using an easily scalable and IC-compatible process. We also investigate the optical properties of these nanostructures. These a-Si:H nanostructures display greatly enhanced absorption over a large range of wavelengths and angles of incidence, due to suppressed reflection. The enhancement effect is particularly strong for a-Si:H NC arrays, which provide nearly perfect impedance matching between a-Si:H and air through a gradual reduction of the effective refractive index. More than 90% of light is absorbed at angles of incidence up to 60° for a-Si:H NC arrays, which is significantly better than NW arrays (70%) and thin films (45%). In addition, the absorption of NC arrays is 88% at the band gap edge of a-Si:H, which is much higher than NW arrays (70%) and thin films (53%). Our experimental data agree very well with simulation. The a-Si:H nanocones functio...