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Topic: Absorption spectroscopy


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  Absorption Spectroscopy
Absorption spectroscopy is used in chemistry and physics to identify the characteristic and unchanging absorption spectrum for specific elements and compounds.
The absorption of quanta of light by substances is determined by the promotion and demotion of electrons to and from atomic and molecular orbitals, and the measured wavelengths are individual and unique to each substance.
In absorption spectroscopy, x-rays can be used to reveal the chemical composition of a substance, and different isomers are revealed by near ultraviolet to near infrared wavelengths.
www.iscid.org /encyclopedia/Absorption_Spectroscopy   (205 words)

  
 Spartanburg SC | GoUpstate.com | Spartanburg Herald-Journal
(Spectroscopy is a word that has come to denote an even wider variety of techniques used in physics and chemistry.) In absorption spectroscopy, the intensity of a beam of light of measured before and after interaction with a sample is compared.
In absorption spectroscopy the absorbed photons are not re-emitted (as in fluorescence) rather, the energy that is transferred to the chemical compound upon absorbance of a photon is lost by non-radiative means, such as transfer of energy as heat to other molecules.
The absorption spectrum can be measured using a spectrometer and by knowing the shape of the spectrum,the optical path length and the amount of radiation absorbed, one can determine the structure and concentration of the compound.
www.goupstate.com /apps/pbcs.dll/section?category=NEWS&template=wiki&text=Absorption_spectroscopy   (1147 words)

  
 TypesSpectroscopy
Absorption spectroscopy is a "workhorse" technology widely used in industry and in chemistry, biology, medicine, and other fields of scientific research.
The roots of absorption spectroscopy can be traced to 1802, when the English chemist William Hyde Wollaston (1766-1828) observed what later became known as the Fraunhofer lines--the many dark lines seen in the spectrum of sunlight.
The advantages of Raman spectroscopy, which are described in previous topics, are that the pretreatment of samples is not necessary, samples are not destroyed, and the interference of water is weak.
www.sas.upenn.edu /~navisjam/TypesSpectroscopy.html   (1437 words)

  
 Absorption spectroscopy Summary
While the relative intensity of the several absorption lines does not vary, at a given wavelength the measured absorbance has been shown to be proportional to the molar concentration of the absorbing species and the thickness of the sample the light passes through.
The plot of absorption versus wavelength for a particular compound is referred to as the absorption spectrum.
The absorption spectrum is measured using a spectrophotometer, which disperses the transmitted light using a diffraction grating and subtracts from the known incident spectrum to determine opacity at each wavelength in the measured range.
www.bookrags.com /Absorption_spectroscopy   (1368 words)

  
 Absorption spectroscopy - Definition, explanation
It is based on the absorption of quanta of light by a chemical substance, due to the promotion of electrons from one orbital to another in that substance.
The absorption spectrum is measured using a spectrophotometer, where a light source coupled with a diffraction grating allows Absorption to be measured at various wavelengths.
Optical absorption spectra are measured from the near ultraviolet to near infrared.
www.calsky.com /lexikon/en/txt/a/ab/absorption_spectroscopy.php   (911 words)

  
 Atomic absorption spectroscopy - Biocrawler
Atomic absorption spectroscopy in analytical chemistry is a technique for determining the concentration of a particular metal element within a sample.
Atomic Absorption Spectroscopy can be used to analyse the concentration of over 62 different metals in a solution.
The technique of Atomic Absorption Spectroscopy was first developed during the 1950's by a team of Australian chemists, lead by Alan Walsh, working at the CSIRO (Commonwealth Science and Industry Research Organisation) Division of Chemical Physics, in Melbourne Australia.
www.biocrawler.com /encyclopedia/Atomic_absorption_spectroscopy   (475 words)

  
  Absorption spectroscopy
(Spectroscopy is a word that has come to denote an even wider variety of techniques used in physics and chemistry.) In absorption spectroscopy, the intensity of a beam of light of measured before and after interaction with a sample is compared.
, absorption spectroscopy is based on the absorption of photons by one or more substances present in a sample, which can be a solid, liquid, or gas, and subsequent promotion of electron(s) from one energy level to another in that substance.
In absorption spectroscopy the absorbed photons are not re-emitted (as in fluorescence) rather, the energy that is transferred to the chemical compound upon absorbance of a photon is lost by non-radiative means, such as transfer of energy as heat to other molecules.
www.photonicsknowledge.com /search/Absorption_spectroscopy   (1181 words)

  
 MLF Cavity Enhanced Absorption Spectroscopy
A simple yet sensitive experimental scheme to record high-resolution optical absorption and/or optical rotation spectra of molecules in open air, cells or jets, using ideas from the field of CRD spectroscopy is demonstrated.
The techniques have been demonstrated by recording absorption spectra of oxygen, water, and ammonia in a cell, oxygen and ammonia in a jet, and magnetic rotation spectra of oxygen in a cell.
Absorption spectra of rotationally cold ammonia molecules have been recorded in the 6400--6630 cm-1 region, using the cavity enhanced absorption technique in combination with a slit nozzle expansion.
www.rijnh.nl /users/berden/cea.html   (916 words)

  
  Dr. Keith A. Walters - Photochemistry at NKU - Molecular Spectroscopy
In absorption spectroscopy, the absorption of light by the molecule of interest is measured.
At this point, the transient absorption signals for both absorptions are zero, since the absorptions have reached the same levels that were observed before the laser fired.
A typical transient absorption spectrum is a plot of delta absorbance versus wavelength for all the wavelengths observed.
www.nku.edu /~walterske/spectra.htm   (1074 words)

  
  atomic absorption spectroscopy Information Center - atomic absorption spectroscopy disadvantages
Atomic absorption spectroscopy in analytical chemistry is a technique for determining the concentration of a particular metal element within a sample.
The atomic absorption applications of atomic absorption spectroscopy spectroscopy experimental disadvantages technique of Atomic Absorption Spectroscopy was first developed during the 1950's by a team of Australian chemists, lead by Alan Walsh, working at the CSIRO (Commonwealth Science and atomic absorption spectroscopy disadvantages Industry Research Organisation) Division of Chemical Physics, in Melbourne Australia.
For analysing the concentration standard atomic absorption spectroscopy of iron of copper in an ore, a copper cathode tube atomic absorption spectroscopy metal ions environment lead would be used, and likewise for any other atomic absorption spectroscopy metal being analysed.
www.scipeeps.com /Sci-Biochemistry_Topics_A/atomic_absorption_spectroscopy.html   (467 words)

  
 Absorption spectroscopy apparatus and method patent invention   (Site not responding. Last check: )
An absorption spectroscopy apparatus according to claim 1, wherein the average radii of the concave cross-sections of the segments of the side wall are equal.
An absorption spectroscopy apparatus according to claim 1, wherein each of the reflective segments of the side wall of the cell has a cross-section taken along a plane extending parallel to the axis of the cell that is concave with respect to the axis.
An absorption spectroscopy apparatus according to claim 11, further comprising an emitter for generating a ray of light and directing the ray of light to the launch/collection reflector, and a detector for receiving the ray of light from the launch/collection reflector.
www.freshpatents.com /Absorption-spectroscopy-apparatus-and-method-dt20061012ptan20060227327.php?type=claims   (641 words)

  
 Absorption spectroscopy apparatus and method patent invention   (Site not responding. Last check: )
Spectroscopy is based on the fact that different chemical compositions absorb energy, e.g., light, at different frequencies, so that measuring the intensity versus the frequency of the light passed through a sample can be used to identify which light frequencies were absorbed by the sample and which were not.
The improved absorption cell of the '603 publication prevents the loss of significant amounts of light through ends of the cell and provides a large throughput, or etendue, so that the amount of light that can be directed through the sample and the sensitivity of the resulting measurement can be increased.
Furthermore, an absorption spectroscopy apparatus incorporating the new and improved multi-pass sample cell preferably will have a smaller total package size, including the source, the detector, the launch optics and the sample cell, in order to be fitted on existing flow streams.
www.freshpatents.com /Absorption-spectroscopy-apparatus-and-method-dt20061012ptan20060227327.php   (1661 words)

  
 atomic absorption spectroscopy Information Center - atomic absorption spectroscopy disadvantages
The technique of Atomic Absorption zinc atomic absorption spectroscopy Spectroscopy was first developed during the 1950's by a team of Australian chemists, lead atomic absorption spectroscopy metal ions environment lead by Alan Walsh, working at the CSIRO (Commonwealth Science and Industry Research Organisation) Division of Chemical Physics, in Melbourne Australia.
A beam of light is focussed through this flame at its longest axis atomic absorption spectroscopy experimental limitations (the lateral axis) onto a detector past the flame.
When a high voltage is applied atomic absorption spectroscopy experimental disadvantages across the anode and cathode, the metal atoms in the cathode are exciting into producing light with a certain emission spectra.
www.scipeeps.com /Sci-Chemistry_Topics_Ap_-_B/atomic_absorption_spectroscopy.html   (467 words)

  
 Cavity Ring Down Spectroscopy - CRD - Cavity Ringdown Spectroscopy - CRDS
The advantage over normal absorption spectroscopy results from (i) the intrinsic insensitivity of the CRD technique to light source intensity fluctuations, and (ii) the extremely long effective path lengths (many kilometers) that can be realized in stable optical cavities.
It is shown that as in the case of `normal' CRD spectroscopy, the measurement is independent of light intensity fluctuations, provided the spectral intensity distribution of the light source is known and is constant during the measurement (reference).
CRD absorption spectra are measured with linearly and circularly polarized light, leading to different \Delta M selection rules in the molecular transition, thereby aiding in the assignment of the spectra.
www.rijnh.nl /users/berden/crd.html   (3271 words)

  
 Researchers demonstrate single molecule absorption spectroscopy
Single molecule absorption spectroscopy can enhance molecular analysis, surface manipulation and studies of molecular energy and reactivity at the atomic level.
Unlike single molecule fluorescence spectroscopy, which is now a commonly used measurement technique, single molecule absorption spectroscopy has been an elusive goal.
"Single molecule absorption spectroscopy is an extremely sensitive technique for analytical chemistry, for measuring electrical properties of molecules, and for studying energy transfer on surfaces," Gruebele said.
www.eurekalert.org /pub_releases/2005-12/uoia-rds122005.php   (453 words)

  
 UV-Vis Absorption Spectroscopy - Theory
For example, the absorption that is observed in the UV region for the carbonyl group in acetone is of the same wavelength as the absorption from the carbonyl group in diethyl ketone.
Absorption of ultraviolet and visible radiation in organic molecules is restricted to certain functional groups (chromophores) that contain valence electrons of low excitation energy.
Absorption of radiation then involves the transfer of an electron from the donor to an orbital associated with the acceptor.
teaching.shu.ac.uk /hwb/chemistry/tutorials/molspec/uvvisab1.htm   (609 words)

  
 LaVision - Absorption Spectroscopy
Absorption Spectroscopy is one of the oldest techniques for the non-intrusive investigation of gaseous media.
The absorption of light is specific for the probed molecule and the wavelength of the light.
Broadband absorption is used for the concentration measurement of functional groups of molecules like for the total hydrocarbon (fuel) concentration measurement inside an engine cylinder.
www.lavision.de /techniques/absorption_spectroscopy.php   (241 words)

  
 UV-Visible Spectroscopy
The corrected absorption value is called "molar absorptivity", and is particularly useful when comparing the spectra of different compounds and determining the relative strength of light absorbing functions (chromophores).
The appearance of several absorption peaks or shoulders for a given chromophore is common for highly conjugated systems, and is often solvent dependent.
All the absorptions do not shift by the same amount, so for anthracene (green shaded box) and tetracene (blue shaded box) the weak absorption is obscured by stronger bands that have experienced a greater red shift.
www.cem.msu.edu /~reusch/VirtualText/Spectrpy/UV-Vis/spectrum.htm   (2049 words)

  
 Atomic Absorption Spectroscopy, Atomic Emission Spectroscopy & Atomic Fluorescence Spectroscopy
Atomic spectroscopy is the determination of elemental composition by its electromagnetic or mass spectrum.
In optical spectroscopy, the energy absorbed to move an electron to a more energetic level and/or the energy emitted as the electron moves to a less energetic energy level is in the form of a photon.
Atomic absorption measures the amount of light at the resonant wavelength which is absorbed as it passes through a cloud of atoms.
www.andor.com /chemistry/?app=91   (987 words)

  
 Defintion of infrared_absorption_spectroscopy_ir - Chemistry Dictionary
Infrared (IR) absorption spectroscopy is the measurement of the wavelength and intensity of the absorption of mid-infrared light by a sample.
The wavelength of many IR absorption bands are characteristic of specific types of chemical bonds, and IR spectroscopy finds its greatest utility for qualitative analysis of organic and organometallic molecules.
IR spectroscopy is used to confirm the identify of a particular compound and as a tool to help determine the structure of a newly synthesized molecule (with NMR spectroscopy and mass spectrometry).
www.chemicool.com /definition/infrared_absorption_spectroscopy_ir.html   (314 words)

  
 Journal of Analytical-Science.com : Atomic Absorption Spectroscopy
Since atomic absorption is relatively inexpensive and fast and requires only a minimum of proper laboratory training, it is an excellent technique for performing first-run analyses of industrial metals.
Soils are ideal for atomic absorption since the particles are already in a finely ground state and often are composed of water-soluble metal salts that lend themselves readily to atomization and analysis.
Atomic absorption instruments are single beam, since it would be extremely difficult to produce a reference beam with its own nebulizer and flame identical to the sample beam.
www.analytical-science.com /Journal/atomicabsorption_2003.htm   (1729 words)

  
 UV-Vis Absorption Spectroscopy - Theory
For example, the absorption that is observed in the UV region for the carbonyl group in acetone is of the same wavelength as the absorption from the carbonyl group in diethyl ketone.
Absorption of ultraviolet and visible radiation in organic molecules is restricted to certain functional groups (chromophores) that contain valence electrons of low excitation energy.
Absorption of radiation then involves the transfer of an electron from the donor to an orbital associated with the acceptor.
www.shu.ac.uk /schools/sci/chem/tutorials/molspec/uvvisab1.htm   (609 words)

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