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Topic: Absorption spectrum


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In the News (Fri 14 Jun 19)

  
  Absorption (electromagnetic radiation) - Wikipedia, the free encyclopedia
In physics, absorption is the process by which the energy of a photon is taken up by another entity, for example, by an atom whose valence electrons make a transition between two electronic energy levels.
The absorption of light during wave propagation is often called attenuation.
For most substances, the amount of absorption varies with the wavelength of the light, leading to the appearance of colour in pigments that absorb some wavelengths but not others.
en.wikipedia.org /wiki/Absorption_(optics)   (198 words)

  
 Absorption spectrum - Wikipedia, the free encyclopedia
A material's absorption spectrum shows the fraction of incident electromagnetic radiation absorbed by the material over a range of frequencies.
An absorption spectrum is, in a sense, the inverse of an emission spectrum.
Absorption spectra can therefore be used to identify elements present in a gas or liquid.
en.wikipedia.org /wiki/Absorption_spectrum   (408 words)

  
 The Solar Spectrum
Balmer H-alpha (6563 Å) region of the solar spectrum
Balmer H-beta (4861 Å) region of the solar spectrum
Balmer H-gamma (4340 Å) region of the solar spectrum
csep10.phys.utk.edu /astr162/lect/sun/spectrum.html   (470 words)

  
 ABSORPTION SPECTRUM OF CHEMICALS USED IN VISION
The overall absorption cross section of the liquid crystal to photons moving parallel to the axes of the molecules is expanded.
The width of the individual absorption characteristics is determined by the conditions of solvation and the specific parameters of the measurement.
As a result of this absorption, the overall spectral sensitivity of the eye is given by the heavy line enclosing the darkest area of the figure.
4colorvision.com /files/absorption.htm   (2253 words)

  
 Greenhouse Gas Absorption Spectrum   (Site not responding. Last check: 2007-10-23)
Absorption spectra for major natural greenhouse gases in the earth's atmosphere.
As an example, if we look at the plot for oxygen and ozone, we see that the absorption is very high in the ultraviolet region but essentially zero in the visible and infrared regions, except for isolated peaks.
The total spectrum of all atmospheric gases is given in the bottom plot.
www.iitap.iastate.edu /gccourse/forcing/spectrum.html   (391 words)

  
 General Chemistry Online: Glossary: Electrons in atoms
Absorption spectra are unique for each element and compound and they are often used as chemical "fingerprints" in analytical chemistry.
A model of the atom that explains emission and absorption of radiation as transitions between stationary electronic states in which the electron orbits the nucleus at a definite distance.
For example, a plot of light absorbance vs. wavelength is an absorption spectrum; a plot of ion abundance vs. mass is a mass spectrum.
antoine.frostburg.edu /chem/senese/101/electrons/glossary.shtml   (1144 words)

  
 Atmospheric Photochemistry via Vibrational Overtone Absorption
Absorption by the Earth of the incoming beam of photons from the sun, which may be approximated by a flbody at about 5800 K, gives rise to an entropy increase of the planet, equal to
Absorption spectroscopic methods are much less sensitive than fluorescence or ionization because of the high background signal associated with the light source but are more universal.
The most straightforward absorption technique is direct absorption spectroscopy, in which the attenuation of the intensity of a stable light source is measured as a function of wavelength.
pubs.acs.org /ncw/2003/articles/cr0206519.html   (8487 words)

  
 CHP - Absorption   (Site not responding. Last check: 2007-10-23)
Absorption spectroscopy is one way to study the energy levels of the atoms, molecules, and solids.
An absorption spectrum is the absorption of light as a function of wavelength.
The spectrum of an atom or molecule depends on its energy-level structure, making absorption spectra useful for identifying compounds.
www.chem.vt.edu /chem-ed/spec/absorption.html   (183 words)

  
 Absorption spectrum
A related phenomenum to the emission spectra of elements is the absorption spectra.
As with the emission spectrum, each element has its own unique absorption spectrum, as the energy levels of different elements differ.
Measuring the absorption spectrum can therefore be used to identify elements in an unknown substance by comparing it to the spectrum of known elements.
theory.uwinnipeg.ca /mod_tech/node152.html   (219 words)

  
 Deep Impact: Science: Spectroscopy   (Site not responding. Last check: 2007-10-23)
When you separate the light that is passing through a sample, or reflecting off a sample, you end up with an emission spectrum or absorption spectrum, as opposed to the continuous spectrum you would get if you break up a source of all wavelengths of light.
Such a spectrum would be created when material is given extra energy somehow (it's heated, electrified, radiated with light, etc.) and that extra energy is later emitted as light energy.
The emission or absorption spectrum of a substance is as unique to that substance as a fingerprint is to a human being.
deepimpact.jpl.nasa.gov /science/spectroscopy.html   (953 words)

  
 L31.  UV Absorption Spectrum of Formyl Radical, HCO
UV absorption spectroscopy is widely used in the determination of the structure and reactivity of free radicals.
UV absorption spectrum of HCO is shown in Fig.
This determination is based on the measured cross-sections of formyl radical and on the equal yields of methyl and formyl radicals in the photolysis of acetaldehyde.
www.cstl.nist.gov /div838/kinetics2001/agenda/l_session/l31/l31.htm   (478 words)

  
 Spectra
The rainbow is a natural spectrum caused by the refraction and reflection of sunlight through raindrops, and shows that sunlight consists of a continuous run - - a continuum -- of colors from red to violet.
The visual spectrum of light, however, is but a tiny portion of the whole picture, of a huge spectrum of radiation that extends in both directions from the edges of the rainbow.
The absorption lines in the Sun and stars can be identified with individual chemical elements or molecular compounds by comparing their positions in the spectrum (their wavelengths) with those observed from pure sources in the laboratory.
www.astro.uiuc.edu /~kaler/sow/spectra.html   (5857 words)

  
 Atomic Absorption and Emission Spectra
The corresponding spectrum may exhibit a continuum, or may have superposed on the continuum bright lines (an emission spectrum) or dark lines (an absorption spectrum), as illustrated in the following figure.
An absorption spectrum occurs when light passes through a cold, dilute gas and atoms in the gas absorb at characteristic frequencies; since the re-emitted light is unlikely to be emitted in the same direction as the absorbed photon, this gives rise to dark lines (absence of light) in the spectrum.
The spectrum of hydrogen is particularly important in astronomy because most of the Universe is made of hydrogen.
csep10.phys.utk.edu /astr162/lect/light/absorption.html   (408 words)

  
 Absorption Spectra
When sunlight was sent through a thin slit and then through one of the prisms, it formed a rainbow-colored spectrum, just as Fraunhofer had expected--but, much to his surprise, the spectrum contained a series of dark lines.
Then the spectrum of light that had been through the gas would just have some gaps in it, at the frequencies that were absorbed.
Under very careful examination, the "continuous" spectrum of sunlight turns out to be an absorption spectrum.
www.colorado.edu /physics/2000/quantumzone/fraunhofer.html   (433 words)

  
 Absorption SPectrum
Different opsins have different absorption spectra as a direct result of their specific electron configuration, resulting in predictable absorption given the bonds in a molecule.
Differences in absorption would not be as high between free 11-cis-retinal and 11-cis-retinal that is bonded via a Schiff base in to retinal, as that amount of conjugation is affected.
There are no sharp peaks in the absorption spectra of the rhodopsins due to the fact that the vibrational and translations states contribute slightly to the spectra (22).
www.sas.upenn.edu /~tareilaj/AbsorptionSpectrum.html   (757 words)

  
 CHP - Infrared Absorption Spectrometers   (Site not responding. Last check: 2007-10-23)
This document describes dispersive and Fourier-transform spectrometers that are used in infrared absorption spectroscopy.
To obtain an IR absorption spectrum, one mirror of the interferometer moves to generate interference in the radiation reaching the detector.
This design does not have the reference cell of a dispersive instrument, so a reference spectrum is recorded and stored in memory to subtract from the sample spectrum.
www.chem.vt.edu /chem-ed/spec/vib/ir-instr.html   (200 words)

  
 Vibration-Rotation Spectrum of HCl
A classic among molecular spectra, the infrared absorption spectrum of HCl can be analyzed to gain information about both rotation and vibration of the molecule.
The absorption lines shown involve transitions from the ground to first excited vibrational state of HCl, but also involve changes in the rotational state.
By treating the vibrational transition in the HCl spectrum from its ground to first excited state as a quantum harmonic oscillator, the bond force constant can be calculated.
hyperphysics.phy-astr.gsu.edu /HBASE/molecule/vibrot.html   (482 words)

  
 Color & The Absorption Spectrum   (Site not responding. Last check: 2007-10-23)
If a portion of the incident radiation (certain wavelengths) is absorbed by the object, the transmitted or reflected light will appear as the complementary color of those wavelengths.
Record in your notebook the wavelength range (in nm) of the visible spectrum; this range goes from the longest wavelength at which you saw color to the shortest wavelength at which you could still see color.
Print out the graph of your spectra and circle the wavelength (nm) of the peak in the spectrum which has the maximum absorbance in the visible region (400-700 nm).
www.pitt.edu /~n3lsk/colorabsproc.html   (1236 words)

  
 General Chemistry Online: Glossary:
Absorption can be a chemical process (a strong solution of NaOH absorbs CO from the air) or a physical process (palladium absorbs hydrogen gas).
(a) extinction coefficient; absorption cross section; decadic absorptivity.
A group or substructure in a molecule that influences the intensity of absorption
antoine.frostburg.edu /chem/senese/101/glossary/a.shtml   (3120 words)

  
 Regents Prep- Spectroscopy, emission, absorption, Doppler shift
We see it as white light but if we use a spectroscope or prism to separate the light by different frequencies, we see it as a spectrum like the one to the left.
The Absorption Spectrum: When atoms are present as a gas, we find that they will absorb only certain colors of light.
Notice the position and colors of the absorption spectrum line up with those of the emission spectrum.
www.regentsprep.org /Regents/physics/phys05/cspectrum/default.htm   (336 words)

  
 Absorption spectrum of melanin.   (Site not responding. Last check: 2007-10-23)
In the near infrared wavelengths of light used for iris recognition (700nm - 900nm), iris pigmentation and apparent colour in the visible band (400nm - 700nm) play almost no role.
The peak absorption of human melanin pigment occurs around 335nm, and absorption is almost completely attenuated for wavelengths longer than 700nm.
The reflectance of the iris is quite constant over the 700nm - 900nm band, although the iris looks much brighter in video images acquired in the longer wavelengths simply because the sclera and skin are much darker (less reflective) in those wavelengths, and so the camera gain setting tends to increase.
www.cl.cam.ac.uk /users/jgd1000/melanin.html   (193 words)

  
 The Absorption Spectrum of Potassium Vapour   (Site not responding. Last check: 2007-10-23)
The method of studying the absorption spectrum was that used first by Roscoe and Schuster, and of late years elaborated by Prof.
A tube with quartz plate ends can thus be used and the absorption spectrum studied with a quartz spectrograph.
The remarkable feature of this absorption spectrum and also that of Sodium as examined by Wood, is the enormous difference in the properties of the principal series lines from those of other lines in the emission spectrum.
stacks.iop.org /1478-7814/22/72   (512 words)

  
 Absorption Spectrum - Compare Prices, Reviews and Buy at NexTag - Price - Review
Sol-X Gray is a general-purpose lens tint that allows uniform absorption throughout the spectrum, permitting colors to be seen exactly as they are with little contrast.
Nutrient-rich, rapid absorption nourishment in a great-tasting liquid formula Contains optimum levels of 68 naturally occurring elements Delivers a broad spectrum of support for...
Provide the exact band of rays within the UVB spectrum for maximum vitamin D3 synthesis and calcium absorption.
www.nextag.com /absorption-spectrum/search-html   (485 words)

  
 APOD: 2005 February 27 - The Solar Spectrum
APOD: 2005 February 27 - The Solar Spectrum
Each day a different image or photograph of our fascinating universe is featured, along with a brief explanation written by a professional astronomer.
above spectrum arise from gas at or above the Sun's surface absorbing sunlight emitted below.
antwrp.gsfc.nasa.gov /apod/ap050227.html   (145 words)

  
 absorption spectrum
spectrum - spectrum, arrangement or display of light or other form of radiation separated according to...
spectrum: Continuous and Line Spectra - Continuous and Line Spectra Dispersion, the separation of visible light into a spectrum, may be...
Add Fact Monster search to your site
www.factmonster.com /ce6/sci/A0909864.html   (53 words)

  
 Energy Citations Database (ECD) - Energy and Energy-Related Bibliographic Citations
Energy Citations Database (ECD) Document #6962546 - Ultraviolet absorption spectrum of gaseous HOCl
Availability information may be found in the Availability, Publisher, Research Organization, Resource Relation and/or Author (affiliation information) fields and/or via the "Full-text Availability" link.
400201 -- Chemical & Physicochemical Properties ;500200 -- Environment, Atmospheric-- Chemicals Monitoring & Transport-- (-1989); HYPOCHLOROUS ACID-- ABSORPTION SPECTROSCOPY;HYPOCHLOROUS ACID-- MASS SPECTROSCOPY; EXPERIMENTAL DATA;OZONE;ULTRAVIOLET RADIATION;ULTRAVIOLET SPECTRA
www.osti.gov /energycitations/product.biblio.jsp?osti_id=6962546   (115 words)

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