WordNet

very thin and insubstantial; "thin paper"; "light summer dresses"
make lighter or brighter; "This lamp lightens the room a bit" (同)illume, illumine, light_up, illuminate
a condition of spiritual awareness; divine illumination; "follow Gods light" (同)illumination
having abundant light or illumination; "they played as long as it was light"; "as long as the lighting was good" (同)lighting
(physics) electromagnetic radiation that can produce a visual sensation; "the light was filtered through a soft glass window" (同)visible_light, visible_radiation
any device serving as a source of illumination; "he stopped the car and turned off the lights" (同)light_source
the visual effect of illumination on objects or scenes as created in pictures; "he could paint the lightest light and the darkest dark" (同)lightness
a particular perspective or aspect of a situation; "although he saw it in a different light, he still did not understand"
a person regarded very fondly; "the light of my life"
a visual warning signal; "they saw the light of the beacon"; "there was a light at every corner"
an illuminated area; "he stepped into the light"
mental understanding as an enlightening experience; "he finally saw the light"; "can you shed light on this problem?"
public awareness; "it brought the scandal to light"
(used of color) having a relatively small amount of coloring agent; "light blue"; "light colors such as pastels"; "a light-colored powder" (同)light-colored
moving easily and quickly; nimble; "the dancer was light and graceful"; "a lightsome buoyant step"; "walked with a light tripping step" (同)lightsome, tripping
having relatively few calories; "diet cola"; "light (or lite) beer"; "lite (or light) mayonnaise"; "a low-cal diet" (同)lite, low-cal, calorie-free
less than the correct or legal or full amount often deliberately so; "a light pound"; "a scant cup of sugar"; "regularly gives short weight" (同)scant, short
(of sleep) easily disturbed; "in a light doze"; "a light sleeper"; "a restless wakeful night" (同)wakeful
(physics, chemistry) not having atomic weight greater than average; "light water is ordinary water"
(used of soil) loose and large-grained in consistency; "light soil"
characterized by or emitting light; "a room that is light when the shutters are open"; "the inside of the house was airy and light"
demanding little effort; not burdensome; "light housework"; "light exercise"
designed for ease of movement or to carry little weight; "light aircraft"; "a light truck"
easily assimilated in the alimentary canal; not rich or heavily seasoned; "a light diet"
having little importance; "losing his job was no light matter"
intended primarily as entertainment; not serious or profound; "light verse"; "a light comedy"
not great in degree or quantity or number; "a light sentence"; "a light accent"; "casualties were light"; "light snow was falling"; "light misty rain"; "light smoke from the chimney"
of comparatively little physical weight or density; "a light load"; "magnesium is a light metal--having a specific gravity of 1.74 at 20 degrees C"
of little intensity or power or force; "the light touch of her fingers"; "a light breeze"
of the military or industry; using (or being) relatively small or light arms or equipment; "light infantry"; "light cavalry"; "light industry"; "light weapons"
psychologically light; especially free from sadness or troubles; "a light heart"
(chemistry) a process in which one substance permeates another; a fluid permeates or is dissolved by a liquid or solid (同)soaking up
(physics) the process in which incident radiated energy is retained without reflection or transmission on passing through a medium; "the absorption of photons by atoms or molecules"
apparatus for supplying artificial light effects for the stage or a film
the craft of providing artificial light; "an interior decorator must understand lighting"
set afire or burning; "the lighted candles"; "a lighted cigarette"; "a lit firecracker" (同)lit

PrepTutorEJDIC

〈U〉『光,光線』;明るさ / 〈U〉夜明け;日中;日光 / 〈C〉『明かり』(太陽・灯火など光を出すもの) / 〈U〉《時にa~》光輝(brightness),(目などの)輝き / 〈C〉(点火するための)火,火花 / 〈C〉明かり採り,採光窓 / 〈C〉《通例単数形で》(絵などの)明るい部分 / 〈U〉(…についての)知識,情報,理解《+『on』+『名』》 / 〈C〉(ものを見る)観点,見地;相 / 〈C〉この世に光を与える人;指導的な人物 / …‘に'『火をつける』《+『up』+『名』+『名』+『up』》 / …‘に'『明かりをつける』,‘を'照らす《+『up』+『名,』+『名』+『up』》 / 〈人〉‘を'明かりをつけて案内する / 〈表情など〉‘を'明るくする《+『up』+『名,』+『名』+『up』》 / 〈物が〉火がつく,点火する;明かりがつく《+『up』》 / 明るくなる,晴れ晴れする《+『up』》 / 『明るい』 / (色が)『薄い』
(重量が)『軽い』 / (いろいろな事について,その程座・量が)軽い,小さい / 『軽快な』 / 軽装の / 肩のこらない;気軽な / 手軽な,骨の折れなし / (食べ物が)消化のよい,もたれない / ふらふらする,目まいのする / アルコール分の少ない / (パンなどが)ふんわりした / (重量が)軽く / (程度が)軽く,容易に;軽装で
(車・馬などから)降りる《+『from』+『名』》(alight) / (木などに)〈鳥などが〉止まる《+『on』(『upon』)+『名』》 / (…に)〈打撃・運などが〉突然ふりかかる《+『on』(『upon』)+『名』》
吸収,併合 / (…に)夢中になること,専心すること《+『in』+『名』》
照明,点火 / 照明方法(装置)
(羊・豚などの)肺臓

Wikipedia preview

出典(authority):フリー百科事典『ウィキペディア（Wikipedia）』「2014/12/08 01:13:04」(JST)

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An overview of electromagnetic radiation absorption. This example discusses the general principle using visible light as 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 transmitted unaffected and, 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.

In physics, absorption of electromagnetic radiation is the way in which the energy of a photon is taken up by matter, typically the electrons of an atom. Thus, the electromagnetic energy is transformed into internal energy of the absorber, for example thermal energy.^[1] The reduction in intensity of a light wave propagating through a medium by absorption of a part of its photons is often called attenuation. Usually, the absorption of waves does not depend on their intensity (linear absorption), although in certain conditions (usually, in optics), the medium changes its transparency dependently on the intensity of waves going through, and saturable absorption (or nonlinear absorption) occurs.

Quantifying absorption

There are a number of ways to quantify how quickly and effectively radiation is absorbed in a certain medium, for example:

The absorption coefficient, and some closely related derived quantities:
- The attenuation coefficient, which is sometimes but not always synonymous with the absorption coefficient
- Molar absorptivity, also called "molar extinction coefficient", 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 (see also mass attenuation coefficient).
- The absorption cross section and scattering cross-section are closely related to the absorption and attenuation coefficients, respectively.
- "Extinction" in astronomy is equivalent to the attenuation coefficient.
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.
Absorbance (also called "optical density") and optical depth (also called "optical thickness") are two related measures of the total light-blocking power of a certain medium with a certain thickness.
Percentage of the incoming light which gets absorbed.

All these quantities measure, at least to some extent, how well a medium absorbs radiation. However, practitioners of different fields and techniques tend to conventionally use different quantities drawn from the list above.

Measuring absorption

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.

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 spectroscopy, in different parts of the spectrum, are ultraviolet–visible spectroscopy, infrared spectroscopy, and X-ray absorption spectroscopy.

Applications

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. Here are a few examples:

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. For example, see computation of radiowave attenuation in the atmosphere used in satellite link design.
In chemistry and materials science, because different materials and molecules will 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.
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.

References

^ West, William. "Absorption of electromagnetic radiation". AccessScience. McGraw-Hill. Retrieved 8 April 2013.

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). ISBN 978-0-19-509161-8.
ProfHoff, Ken Mellendorf, and Vince Calder (November 2010). "Reflection and Absorption". Physics Archive - Ask a scientist. Argonne National Laboratory. Retrieved 2010-11-14.

External links

UpToDate Contents

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We report herein, nitrogen doped TiO2 nanostructure synthesized by simple microwave assisted method, where ammonia was used as hydrolyzing agent. The synthesized nanomaterials were characterized by means of X-ray diffraction (XRD) which demonstrated that N-doped TiO2 is in anatase phase with average
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Investigation into physical-chemical variables affecting the manufacture and dissolution of wet-milled clarithromycin nanoparticles.

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In vitro studies on the behavior of salmeterol xinafoate and its interaction with calf thymus DNA by multi-spectroscopic techniques.

Zhao T1, Bi S2, Wang Y1, Wang T1, Pang B3, Gu T3.
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The salmeterol xinafoate (SX) binding to calf thymus DNA in vitro was explored by fluorescence, resonance light scattering (RLS), UV-vis absorption, as well as viscometry, ionic strength effect and DNA melting techniques. It was found that SX could bind to DNA weakly, and the binding constants (Ka)
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Japanese Journal

Compact Slow-Light Electro-Absorption Modulator Laterally Integrated with 980 nm Vertical-Cavity Surface-Emitting Laser

Shimada Toshikazu,Matsutani Akihiro,Koyama Fumio
Applied Physics Express 6(12), 122102-122102-4, 2013-12-25
… We demonstrate a compact slow-light electro-absorption modulator laterally integrated with a single-mode 980 nm vertical-cavity surface-emitting laser (VCSEL). … Lateral optical coupling from a VCSEL to a slow-light modulator based on a Bragg reflector waveguide was realized and the electrical isolation between these devices was achieved by ion implantation. …
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Effects of Interference between Energy Absorption Processes of Molecule and Surface Plasmons on Light Emission Induced by Scanning Tunneling Microscopy

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J Phys Soc Jpn 82(12), 124707-124707-11, 2013-12-15
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