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Topic: IR spectroscopy


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  Resonance Raman spectroscopy - Wikipedia, the free encyclopedia
IR spectroscopy involves measuring the direct absorption of photons with the appropriate energy to excite molecular bond vibrations.
This is the mechanism by which IR spectroscopy operates: infrared radiation is passed through the sample, and the intensity of the transmitted light is compared with that of the incident light.
As opposed to IR spectroscopy, where a transition can only be seen when that particular vibration causes a net change in dipole moment of the molecule, in Raman only transitions where the polarizability of the molecule changes can be observed.
en.wikipedia.org /wiki/Resonance_Raman_spectroscopy   (2950 words)

  
 Infrared spectroscopy - Wikipedia, the free encyclopedia
Infrared spectroscopy (IR Spectroscopy) is the subset of spectroscopy that deals with the Infrared part of the electromagnetic spectrum.
The resonant frequencies or vibrational frequencies are determined by the shape of the molecular potential energy surfaces, the masses of the atoms and, eventually by the associated vibronic coupling.
Infrared spectroscopy is widely used in both research and industry as a simple and reliable technique for measurement, quality control, and dynamic measurement.
en.wikipedia.org /wiki/Infrared_spectroscopy   (1326 words)

  
 Chemistry 101: Raman Spectroscopy   (Site not responding. Last check: 2007-10-24)
Raman spectroscopy is closely related to infrared (IR) spectroscopy, in that it records the vibrating, stretching, and bending movements of molecules.
IR spectroscopy, which measures how much light is scattered from a sample and how much is absorbed, relies on this same-wavelength light.
Unlike IR spectroscopy, where water generates such a strong signal that it covers up entire regions of the spectrum, Raman is very insensitive to the presence of water.
www.chemistry.org /portal/a/c/s/1/feature_tea.html?id=c373e901945570368f6a17245d830100   (688 words)

  
 MIT Chemistry: Andrei Tokmakoff
We are using 2D IR spectroscopy of the OH stretch of water to describe the manner in which hydrogen-bonds break and reform, reveal the nature of the collective motions of water that drive hydrogen bond breaking, and follow the structural evolution of the liquid.
Infrared spectroscopy of amide transitions has great potential for studying the structure and dynamics of proteins, but this requires a quantitative understanding of the IR spectroscopy of protein secondary and tertiary structures.
We are using 2D IR spectroscopy of amide transitions to understand the structural basis of collective amide vibrations in model peptides.
web.mit.edu /chemistry/www/faculty/tokmakoff.html   (564 words)

  
 Spectroscopy : Near Infrared (IR) Spectroscopy
Spectroscopy is a technique that uses the interaction of energy with a sample to perform an analysis.
A spectrum is a plot of the intensity of energy detected versus the wavelength (or mass or momentum or frequency, etc.) of the energy.
In simplest terms, spectroscopy requires an energy source and a device for measuring the change in the energy source after it has interacted with the sample (a spectrophotometer or interferometer).
www.camo.com /rt/Resources/spectroscopy.html   (288 words)

  
 Infra red Absorption Spectroscopy - Theoretical Principles
IR radiation does not have enough energy to induce electronic transitions as seen with UV.
Absorption of IR is restricted to compounds with small energy differences in the possible vibrational and rotational states.
For a molecule to absorb IR, the vibrations or rotations within a molecule must cause a net change in the dipole moment of the molecule.
www.shu.ac.uk /schools/sci/chem/tutorials/molspec/irspec1.htm   (411 words)

  
 Introduction to IR Spectra
The category of EM radiation is termed infrared (IR) radiation, and its application to organic chemistry known as IR spectroscopy.
Thus IR spectroscopy involves collecting absorption information and analyzing it in the form of a spectrum -- The frequencies at which there are absorptions of IR radiation ("peaks" or "signals") can be correlated directly to bonds within the compound in question.
As mentioned previously, one of the major factors influencing the IR absorption frequency of a bond are the identity of the two atoms involved.
www.chem.ucla.edu /~webspectra/irintro.html   (986 words)

  
 Infrared identification of organic unknowns
For example, in ethane, the bond between the carbon atoms does not absorb IR because there is a methyl group at each end of the bond.
At this point in your study of IR spectroscopy, you can't tell which compound is an aldehyde and which is a ketone.
IR spectra can be used to identify molecules by recording the spectrum for an unknown and comparing this to a library or data base of spectra of known compounds.
scidiv.bcc.ctc.edu /wv/irsp/eir.html   (2022 words)

  
 Ch13 - IR Spectroscopy   (Site not responding. Last check: 2007-10-24)
Infra red (IR) spectroscopy deals with the interaction between a molecule and radiation from the IR region of the EM spectrum (IR region = 4000 - 400 cm
IR radiation causes the excitation of the vibrations of covalent bonds within that molecule.
An IR spectrum show the energy absorptions as one 'scans' the IR region of the EM spectrum.
library.tedankara.k12.tr /carey/ch13-ir-1.html   (261 words)

  
 IR Spectroscopy
When IR radiation is sent through a sample it interacts with the molecules, causing the chemical bonds to vibrate as the molecules absorb the radiation.
Each functional group of gases is characterized by the tendency to absorb IR radiation of a particular wavelength, regardless of the structure of the rest of the molecule.
The only substances that cannot be analyzed with IR spectroscopy are those that exist as single atoms with no chemical bonds, such as noble gases, and homonuclear diatomic molecules, because they have no dipole movement.
www.naspco.com /article3pt06.htm   (667 words)

  
 IR Spectrum
Spectroscopy is the study of the interaction of electromagnetic radiation with matter.
There are many forms of spectroscopy, each contributing useful information to identify substances and to determine various characteristics of their structure.
Because the IR spectrum of each molecule is unique, it can serve as a signature or fingerprint to identify the molecule.
www.wag.caltech.edu /home/jang/genchem/infrared.htm   (2475 words)

  
 Infrared Spectroscopy   (Site not responding. Last check: 2007-10-24)
Infrared (IR) spectroscopy is a way to measure characteristic vibrations of molecules, making it one of the most popular techniques in chemistry for the last 45 years.
Because of its versatility and convenience, IR spectroscopy is now an essential in almost every branch of chemistry.
With the introduction of Fourier Transform IR spectrometry (FT-IR), IR instruments were suddenly able to produce better spectra in less time than ever before.
www.wooster.edu /chemistry/is/brubaker/ir/default.html   (396 words)

  
 5.4 Vibrational Spectroscopy
Vibrational spectroscopy provides the most definitive means of identifying the surface species generated upon molecular adsorption and the species generated by surface reactions.
There are a number of ways in which the IR technique may be implemented for the study of adsorbates on surfaces.
This modification of the IR technique can be employed with high surface area catalytic samples that are not sufficiently transparent to be studied in transmission.
www.chem.qmul.ac.uk /surfaces/scc/scat5_4.htm   (1431 words)

  
 Spectroscopy for the Aspirin Project
Spectroscopy, the study of how light and matter interact, is one of the most widely used and powerful analytical tools of modern-day chemists.
IR spectroscopy measures energy changes involving vibrations of groups of atoms, usually a bond or set of bonds, within a molecule.
Although this is a much more sensitive technique than IR spectroscopy, and thus better suited for analytical purposes, uv-vis spectra are rarely characteristic of the sample.
home.eckerd.edu /~hudsonrl/chn/CH122/SpecAsp.htm   (934 words)

  
 Characterization by IR spectroscopy
The IR bands of alkali metal-exchanged zeolites X, Y and ZSM-5 shift to lower frequencies (red shift) in the sequence of Na, Rb Cs, that is, with increasing cation mass.
They may be detected and characterized by IR spectroscopy as such due to their vibration modes (OH fundamental, overtone and combination vibrations) or with the help of probe molecules (see preceding paragraph and Refs.
Finally, it should be mentioned that Lewis and Bronsted acidity of zeolites is often advantageously characterized by a combination of IR spectroscopy and other techniques such as temperature-programmed desorption or microcalorimetric measurements of adsorbed probe molecules.
www.iza-online.org /synthesis/VS_2ndEd/IR_Spectroscopy.htm   (1279 words)

  
 Mid-Infrared Spectroscopy | Near-IR Spectroscopy | UV Visible Spectroscopy | Raman Spectroscopy   (Site not responding. Last check: 2007-10-24)
The attractiveness of mid-IR spectroscopy stems from the fact that it directly monitors the fundamental vibrations corresponding to the functional groups that govern the chemical properties of interest.
Mid-IR spectroscopy is the old-timer of molecular spectroscopy, having been in-use for industrial process analysis since the early 1940's.
One IR transparent material that has both a refractive index and very high chemical resistance is diamond.
www.goaxiom.com /an-923.html   (2534 words)

  
 Expert: Material Analysis/Spectroscopy Expert
He and his colleagues are now applying this technique to a variety of time-resolved and phase-resolved infrared spectroscopy problems, as well as to photoacoustic spectroscopy.
This work has included cryogenic linear dichroism and circular dichroism (absorption) spectroscopy of single crystals of transition metal complexes, as well as circular dichroism spectroscopy of solutions of transition metal complexes, solution circularly polarized luminescence of lanthanide complexes of chiral macrocycles, and specular reflectance linear dichroism of single crystals.
In the mirage effect, light absorbed by a solid generates a thermal gradient in the surrounding medium at the surface which is probed by a laser beam.
www.intota.com /viewbio.asp?bioID=604188&perID=718033   (1140 words)

  
 Re: 'How can bond strengths be determinated by means of IR spectroscopy?
Spectroscopy is the study of the interaction of electromagnetic radiation with a chemical substance.
IR absorption bands are common in most organic and inorganic compounds.
When IR light in incident on the molecule, the frequency, which matches the natural frequency of that molecule, is absorbed resulting on molecular vibrations.
www.madsci.org /posts/archives/apr2002/1018624461.Ch.r.html   (264 words)

  
 Vibrational Spectroscopy | Spectroscopy | Infrared Spectroscopy | IR Spectroscopy | Axiom Analytical   (Site not responding. Last check: 2007-10-24)
This is quite useful in estimating the performance of lightguides used in vibrational spectroscopy.
Although the entrance of the smaller lightguide is at the focal point of the paraboloid rather than at the output of a two element beam condenser, the distribution of rays at this point is the same.
Spectroscopy of Surface Films and Powders Using a Metal Light Pipe’, Applied Spectroscopy, 41 553 (1987).
www.goaxiom.com /an-917.html   (3067 words)

  
 Physics Encyclopedia: Optical spectroscopy
Spectroscopy - a larger set of online lecture notes by T. Cafolla; covers vibrational, rotational and Raman spectroscopy.
Spectroscopy on Internet - a very large list of links related to IR and sub-IR spectroscopy - spectra databases, research groups, online publications, tutorials, newsgroups etc.
Spectroscopy - a very rich site on intrumentation, methods and techniques of experimental spectroscopy; by SciMedia.
members.tripod.com /~IgorIvanov/physics/spectroscopy.html   (259 words)

  
 Dynamics: Infrared Spectroscopy
Vibrational spectroscopy (or infrared spectroscopy) measures transitions from one molecular vibrational energy level to another, and requires radiation from the infrared portion of the electromagnetic spectrum.
IR spectroscopy, then, deals with transitions between vibrational energy levels in molecules.
An IR spectrum is displayed as a plot of the energy of the infrared radiation (usually expressed in wavenumbers) versus the percent of light transmitted by the compound.
www.wpi.edu /Academics/Depts/Chemistry/Courses/General/infrared.html   (3404 words)

  
 Attenuated Total Reflectance Fourier Spectroscopy (ATR/FTIR)   (Site not responding. Last check: 2007-10-24)
IR radiation is focused onto the end of the IRE.
This technique can be used to monitor bacterial attachment and biofilm growth on the surface of an IRE or the surface of cellulose acetate.
IR spectra were collected periodically throughout the experiment.
www.micromemanalytical.com /ATR_Ken/ATR.htm   (1946 words)

  
 IR Spectroscopical Imaging of Prostate Adenocarcinoma
IR Spectroscopy Applied to the Study of Prostate Cancer
The technique is particularly well-suited as an adjunct tool for histopathological evaluation of neoplasia, since it provides quantitative chemical information while preserving the sample morphology that is critical for traditional histopathological assessment.
Alternatively, one can choose a specific IR wavelength and view a two-dimensional image of the sample where pixel brightness is scaled to the absorption values at that wavelength.
cgap-mf.nih.gov /Protocols/ProtocolsInDevelopment/IRSpectroscopicImagingofProstaticAdenocarcinoma.html   (456 words)

  
 Vibrational Spectroscopy   (Site not responding. Last check: 2007-10-24)
Infrared spectroscopy (IR Spectroscopy) uses the infrared portion of the electromagnetic spectrum.
As with all spectroscopic techniques, IR spectroscopy can be used to investigate the composition of samples.
Laboratory spectroscopy using long-wavelength infrared light to identify and characterize target molecules.
www.intertek-cb.com /newsitetest/news/vibrationalspectroscopy.shtml   (283 words)

  
 Some useful FTIR information   (Site not responding. Last check: 2007-10-24)
Glossary of Vibrational Spectroscopy Terms reproduced from the Handbook of Vibrational Spectroscopy.
IR beamlines are being planned or are under construction at: Canadian Light Source, SRRC (Taiwan), ANKA (Karlsruhe, Germany), DELTA (Dortmund, Germany), NSRC, (Hefei, China), SPring-8 (Japan), CAMD (Baton-Rouge, USA), SLS (Switzerland), and SESAME (Middle East).
Synchrotron Radiation in infrared spectroscopy, by Allan Morris.
infrared.als.lbl.gov /FTIRinfo.html   (499 words)

  
 InPhotonics: What is Raman spectroscopy?
Raman spectroscopy provides information about molecular vibrations that can be used for sample identification and quantitation.
Raman spectroscopy can be used to measure bands of symmetric linkages which are weak in an infrared spectrum (e.g.
As in infrared spectroscopy, band areas are proportional to concentration, making Raman amenable to quantitative analysis.
www.inphotonics.com /raman.htm   (623 words)

  
 Forensic Applications of IR
Infrared spectroscopy is useful for identifying substances and confirming their identity.
For example, IR can be used to locate the make, model, and year of car by analyzing a paint chip.
Using infrared spectroscopy, a forensic chemist matches the paint on the crowbar to paint on the door of the house that was burglarized.
www.mtholyoke.edu /~mlyount/MySites/ForensicSpectroscopy/ForensicApps.html   (807 words)

  
 IR Spectroscopy
The most useful information you should be able to read in an IR spectrum is what functional groups are present.
To help understand IR, it is useful to compare a vibrating bond to the physical model of a vibrating spring system.
In general, when you are trying to work out what a molecule is, you will not just have the IR spectrum, but you will have other information as well, such as the formula or most likely the NMR.
library.tedankara.k12.tr /carey/ir.html   (447 words)

  
 Open Directory - Science: Physics: Optics: Spectroscopy   (Site not responding. Last check: 2007-10-24)
Atomic Spectroscopy - A compendium of basic ideas, notation, data and formulas from the NIST Physics laboratory.
The Science of Spectroscopy - Wiki technology based project to explain spectroscopy, the use of light to study matter.
The Spectroscopy Net - An open, free resource for spectroscopist everywhere and everyone interested in atomic spectroscopy, including the optical emission spectroscopy network, ICP, spark emission, glow discharge, conferences, manufacturers, suppliers, laboratories, books, reviews, theory and operation.
dmoz.org /Science/Physics/Optics/Spectroscopy   (411 words)

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