Electromagnetic reflectance and emissivity are complementary radiative properties describing how materials interact with incident and thermally emitted electromagnetic radiation as a function of wavelength, polarization, and angle. Reflectance quantifies the fraction of incident radiant flux reflected by a surface, decomposable into specular and diffuse components and governed by Fresnel relations and surface roughness. Emissivity is the ratio of a surface’s spectral radiance to that of an ideal blackbody at the same temperature, constrained by Kirchhoff’s law such that, under thermal equilibrium, spectral emissivity equals spectral absorptance. Together, these properties are fundamental for radiative transfer modeling, remote sensing retrievals, thermal infrared imaging, and energy balance analysis.
Rapid advancements in the electronics industry have provided significant convenience for civilian use, but have also contributed to electromagnetic pollution, posing risks to human safety. To meet the diverse requirements ...
Nanomaterials
Oct 21, 2024
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Optical materials are essential in many modern applications, but controlling the way a material reflects light on its surface is costly and difficult. Now, in a recent study, researchers from Japan found a simple and low-cost ...
Optics & Photonics
Aug 22, 2024
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79
The Brewster reflectionless effect stands out as one of the simplest yet pivotal discoveries in manipulating waves. Initial investigations were limited to isotropic materials, but later, thanks to the advent of metamaterials, ...
Condensed Matter
Jul 10, 2024
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119
Wavelength-selective thermal emitters (WS-TEs) have been frequently designed to achieve desired target emissivity spectra, as in typical emissivity engineering, for broad applications such as thermal camouflage, radiative ...
Optics & Photonics
Feb 8, 2024
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81
Camouflage refers to the ability to reduce the signal captured by detectors, thereby improving survival rates. However, the combination of detectors operating in multiple spectral bands poses a significant challenge, necessitating ...
Optics & Photonics
Feb 7, 2024
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74
Thermal radiation is electromagnetic radiation emitted by all objects with temperature and most representatively, there is the solar radiation spectrum that enters the Earth and causes the greenhouse effect.
Nanophysics
Feb 5, 2024
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116
As summer turns to fall, many people will be turning off the air conditioning and firing up heaters instead. But traditional heating and cooling systems are energy-intensive, and because they typically run on fossil fuels, ...
Nanomaterials
Sep 20, 2023
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121
With a flick of a switch, current technologies allow you to quickly change materials from being dark to light, or cold to hot, just by blocking or transmitting specific wavelengths. But now, inspired by squid skin, researchers ...
Nanomaterials
Jun 28, 2023
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141
An international team of researchers, led by Drexel University, has found that a thin coating of MXene—a type of two-dimensional nanomaterial discovered and studied at Drexel for more than a decade—could enhance a material's ...
Nanophysics
Mar 30, 2023
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501
When we encounter metals in our day-to-day lives, we perceive them as shiny. That's because common metallic materials are reflective at visible light wavelengths and will bounce back any light that strikes them. While metals ...
Nanophysics
Oct 26, 2022
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