An overview of absorption of electromagnetic radiation. This example shows the general principle using visible light as a specific example. A white light source — emitting light of multiple wavelengths — is focused on a sample (the pairs of complementary colors are indicated by the yellow dotted lines). Upon striking the sample, photons that match the energy gap of the molecules present (green light in this example) are absorbed, exciting the molecules. Other photons are scattered (not shown here) or transmitted unaffected; if the radiation is in the visible region (400–700 nm), the transmitted light appears as the complementary color (here red). By recording the attenuation of light for various wavelengths, an absorption spectrum can be obtained.
A notable effect of the absorption of electromagnetic radiation is attenuation of the radiation; attenuation is the gradual reduction of the intensity of light waves as they propagate through the medium.
Although the absorption of waves does not usually depend on their intensity (linear absorption), in certain conditions (optics) the medium's transparency changes by a factor that varies as a function of wave intensity, and saturable absorption (or nonlinear absorption) occurs.
Related measures, including absorbance (also called "optical density") and optical depth (also called "optical thickness")
All these quantities measure, at least to some extent, how well a medium absorbs radiation. Which among them practitioners use varies by field and technique, often due simply to the convention.
Measuring absorptionedit
The absorbance of an object quantifies how much of the incident light is absorbed by it (instead of being reflected or refracted). This may be related to other properties of the object through the Beer–Lambert law.
In medicine, X-rays are absorbed to different extents by different tissues (bone in particular), which is the basis for X-ray imaging.
In chemistry and materials science, different materials and molecules absorb radiation to different extents at different frequencies, which allows for material identification.
In optics, sunglasses, colored filters, dyes, and other such materials are designed specifically with respect to which visible wavelengths they absorb, and in what proportions they are in.
In biology, photosynthetic organisms require that light of the appropriate wavelengths be absorbed within the active area of chloroplasts, so that the light energy can be converted into chemical energy within sugars and other molecules.
In physics, the D-region of Earth's ionosphere is known to significantly absorb radio signals that fall within the high-frequency electromagnetic spectrum.
In nuclear physics, absorption of nuclear radiations can be used for measuring the fluid levels, densitometry or thickness measurements.[2]
In scientific literature is known a system of mirrors and lenses that with a laser "can enable any material to absorb all light from a wide range of angles."[3]
^Baird, Christopher S. (September 2019). "Absorption of electromagnetic radiation". AccessScience. McGraw-Hill. doi:10.1036/1097-8542.001600. Retrieved 17 June 2023.
^M. Falahati; et al. (2018). "Design, modelling and construction of a continuous nuclear gauge for measuring the fluid levels". Journal of Instrumentation. 13 (2): P02028. Bibcode:2018JInst..13P2028F. doi:10.1088/1748-0221/13/02/P02028. S2CID 125779702.
^"Anti-laser enables near-perfect light absorption". Physics World. August 31, 2022.
Thomas, Michael E. (January 2006). Optical Propagation in Linear Media: Atmospheric Gases and Particles, Solid-State Components, and Water. Oxford University Press, USA. pp. 3... (Chapter 1, 2, 7). Bibcode:2006oplm.book.....T. ISBN978-0-19-509161-8. {{cite book}}: |journal= ignored (help)
ProfHoff, Ken Mellendorf; Vince Calder (November 2010). . Physics Archive - Ask a scientist. Argonne National Laboratory. Archived from the original on 2010-11-21. Retrieved 2010-11-14.
January 01, 1970
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This article includes a list of general references but it lacks sufficient corresponding inline citations Please help to improve this article by introducing more precise citations November 2010 Learn how and when to remove this message In physics absorption of electromagnetic radiation is how matter typically electrons bound in atoms takes up a photon s energy and so transforms electromagnetic energy into internal energy of the absorber for example thermal energy 1 An overview of absorption of electromagnetic radiation This example shows the general principle using visible light as a specific example A white light source emitting light of multiple wavelengths is focused on a sample the pairs of complementary colors are indicated by the yellow dotted lines Upon striking the sample photons that match the energy gap of the molecules present green light in this example are absorbed exciting the molecules Other photons are scattered not shown here or transmitted unaffected if the radiation is in the visible region 400 700 nm the transmitted light appears as the complementary color here red By recording the attenuation of light for various wavelengths an absorption spectrum can be obtained A notable effect of the absorption of electromagnetic radiation is attenuation of the radiation attenuation is the gradual reduction of the intensity of light waves as they propagate through the medium Although the absorption of waves does not usually depend on their intensity linear absorption in certain conditions optics the medium s transparency changes by a factor that varies as a function of wave intensity and saturable absorption or nonlinear absorption occurs Contents 1 Quantifying absorption 2 Measuring absorption 3 Applications 4 See also 5 ReferencesQuantifying absorption editMain article Mathematical descriptions of opacity Many approaches can potentially quantify radiation absorption with key examples following The absorption coefficient along with some closely related derived quantities The attenuation coefficient NB used infrequently with meaning synonymous with absorption coefficient citation needed The Molar attenuation coefficient also called molar absorptivity which is the absorption coefficient divided by molarity see also Beer Lambert law The mass attenuation coefficient also called mass extinction coefficient which is the absorption coefficient divided by density The absorption cross section and scattering cross section related closely to the absorption and attenuation coefficients respectively Extinction in astronomy which is equivalent to the attenuation coefficient Other measures of radiation absorption including penetration depth and skin effect propagation constant attenuation constant phase constant and complex wavenumber complex refractive index and extinction coefficient complex dielectric constant electrical resistivity and conductivity Related measures including absorbance also called optical density and optical depth also called optical thickness All these quantities measure at least to some extent how well a medium absorbs radiation Which among them practitioners use varies by field and technique often due simply to the convention Measuring absorption editThe absorbance of an object quantifies how much of the incident light is absorbed by it instead of being reflected or refracted This may be related to other properties of the object through the Beer Lambert law Precise measurements of the absorbance at many wavelengths allow the identification of a substance via absorption spectroscopy where a sample is illuminated from one side and the intensity of the light that exits from the sample in every direction is measured A few examples of absorption are ultraviolet visible spectroscopy infrared spectroscopy and X ray absorption spectroscopy Applications edit nbsp Rough plot of Earth s atmospheric transmittance or opacity to various wavelengths of electromagnetic radiation including visible light Understanding and measuring the absorption of electromagnetic radiation has a variety of applications In radio propagation it is represented in non line of sight propagation For example see computation of radio wave attenuation in the atmosphere used in satellite link design In meteorology and climatology global and local temperatures depend in part on the absorption of radiation by atmospheric gases such as in the greenhouse effect and land and ocean surfaces see albedo In medicine X rays are absorbed to different extents by different tissues bone in particular which is the basis for X ray imaging In chemistry and materials science different materials and molecules absorb radiation to different extents at different frequencies which allows for material identification In optics sunglasses colored filters dyes and other such materials are designed specifically with respect to which visible wavelengths they absorb and in what proportions they are in In biology photosynthetic organisms require that light of the appropriate wavelengths be absorbed within the active area of chloroplasts so that the light energy can be converted into chemical energy within sugars and other molecules In physics the D region of Earth s ionosphere is known to significantly absorb radio signals that fall within the high frequency electromagnetic spectrum In nuclear physics absorption of nuclear radiations can be used for measuring the fluid levels densitometry or thickness measurements 2 In scientific literature is known a system of mirrors and lenses that with a laser can enable any material to absorb all light from a wide range of angles 3 See also editAbsorption spectroscopy Albedo Attenuation Electromagnetic absorption by water Hydroxyl ion absorption Optoelectronics Photoelectric effect Photosynthesis Solar cell Spectral line Total absorption spectroscopy Ultraviolet visible spectroscopyReferences edit Baird Christopher S September 2019 Absorption of electromagnetic radiation AccessScience McGraw Hill doi 10 1036 1097 8542 001600 Retrieved 17 June 2023 M Falahati et al 2018 Design modelling and construction of a continuous nuclear gauge for measuring the fluid levels Journal of Instrumentation 13 2 P02028 Bibcode 2018JInst 13P2028F doi 10 1088 1748 0221 13 02 P02028 S2CID 125779702 Anti laser enables near perfect light absorption Physics World August 31 2022 Thomas Michael E January 2006 Optical Propagation in Linear Media Atmospheric Gases and Particles Solid State Components and Water Oxford University Press USA pp 3 Chapter 1 2 7 Bibcode 2006oplm book T ISBN 978 0 19 509161 8 a href Template Cite book html title Template Cite book cite book a journal ignored help ProfHoff Ken Mellendorf Vince Calder November 2010 Reflection and Absorption Physics Archive Ask a scientist Argonne National Laboratory Archived from the original on 2010 11 21 Retrieved 2010 11 14 Retrieved from https en wikipedia org w index php title Absorption electromagnetic radiation amp oldid 1220246568, 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