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.

Bias in Filter-Based Aerosol Light Absorption Measurements Due to Organic Aerosol Loading: Evidence from Laboratory Measurements

Abstract: Light absorption by soot or nigrosin dye aerosol particles were measured in the laboratory using a particle soot absorption photometer (PSAP) and a photo-acoustic spectrometer (PAS) to assess the influence of non-absorbing organic aerosol (OA) on the PSAP measurements. For the PSAP, particle light absorption is measured after collection on a filter, whereas for the PAS light absorption is measured while the particles remain suspended in the gas phase. OA was generated from the reaction of α -pinene with ozone. It was observed that the presence of this OA in an external mixture of absorbing aerosol and OA can cause an increase in the light absorption measured by the PSAP, relative to that measured by the PAS, by more than a factor of two. This enhancement in the PSAP absorption was found to increase as the amount of OA increased relative to the absorbing compound. Additionally, experiments where absorbing aerosol was deposited on a PSAP filter prior to addition of OA demonstrated that the non-absorbing OA ...

Breakdown and heating of gases under the influence of a laser beam

Abstract: CONTENTS Introduction 650 I. Gas Breakdown 651 1. Measurements of Threshold Parameters 651 2. Multiquantum Photoeffect 654 3. Cascade Ionization (Qualitative Picture) 656 4. Growth of Electron Energy in Radiation Field 657 5. Calculations of Cascade Ionization 660 II. Absorption of Beam and Heating of Gas 6. Measurements of Absorption and Scattering of a Laser Beam and Heating of the Gas in the Breakdown Region 661 7. Wave of Light Absorption and Gas Heating. "Detonation" Mechanism 663 8. "Breakdown" and "Radiative" Mechanisms 666 9. The Spark as a Strong Explosion. Spark in a Magnetic Field 668 10. Production of Plasma from a Solid Target 670 11. Conditions of High-temperature Heating of Hydrogen 671 12. Literature

Nanoscale energy deposition by X-ray absorbing nanostructures.

Abstract: Here we wish to demonstrate a unique property of nanomaterials: energy deposition with nanometer precision from low-energy electrons released from these nanostructures interacting with hard X-ray radiation in aqueous solution. Three effects combine to cause this phenomenon: (1) localized absorption of X-rays by nanostructures, (2) effective release of low-energy electrons from small nanostructures, and (3) efficient deposition of energy in water in the form of radicals and electrons. This combination creates localized X-ray absorption and localized energy deposition of nanometer precision. We confirmed the theoretically predicted nanoscale energy deposition distribution by measuring hydroxyl radical-induced DNA strand breaks, and observed enhanced damage to a 5600-bp DNA molecule from approximately 10 chemically conjugated small gold nanoparticles under X-ray radiation. These results provide a general guidance to applications of this new concept in many fields including radiation chemistry, radiology, radiation oncology, biochemistry, biology, and nanotechnology.

Visible Light Absorption by Various Titanium Dioxide Specimens

Abstract: A set of heat-induced and photoinduced absorption spectra of various compositions of Degussa P25 TiO2 and different polymers has been examined The spectra are described as the sum of overlapping absorption bands (ABs) with maxima at 290 eV (427 nm, AB1), 255 eV (486 nm, AB2), and 205 eV (604 nm, AB3); the spectra correlate entirely with the experimentally observed absorption spectra after the reduction of TiO2 Absorption spectra of visible-light-active TiO2 photocatalysts reported recently in the literature have also been analyzed Relatively narrow absorption spectra are very similar and independent of the method of photocatalyst preparation The average absorption spectrum can be described reasonably well by the sum of the two absorption bands AB1 and AB2 It is argued that visible light activation of TiO2 specimens (anion-doped or otherwise) implicates defects associated with oxygen vacancies that give rise to color centers displaying these absorption bands and not to a narrowing of the original band gap of TiO2 (EBG approximately 32 eV, anatase) through mixing of dopant and oxygen states, as has been suggested recently in the literature

Ultrafast Nonlinear Excitation Dynamics of Black Phosphorus Nanosheets from Visible to Mid-Infrared

Abstract: The recent progress on black phosphorus makes it a promising candidate material for broadband nanophotonic devices, especially operating in the mid-infrared spectral region. Here, the excited carrier dynamics and nonlinear optical response of unoxidized black phosphorus nanosheets and their wavelength dependence were systematically studied from 800 nm to 2.1 μm. The wavelength-dependent relaxation times of black phosphorus nanosheets are determined to be 360 fs to 1.36 ps with photon energies from 1.55 to 0.61 eV. In a comparative study with graphene, we found that black phosphorus has a faster carrier relaxation in near- and mid-infrared region. With regard to nonlinear optical absorption, the response of black phosphorus significantly increases from near- to mid-infrared, and black phosphorus is also confirmed to be better as saturable absorber to MoS2 in infrared region.