FTIR analysis measures the range of wavelengths in the infrared region that are absorbed by a material. This is accomplished through the application of infrared radiation IR to samples of a material.
Unknown materials are identified by searching the spectrum against a database of reference spectra. Materials can be quantified using the FTIR materials characterization technique as long as a standard curve of known concentrations of the component of interest can be created.
FTIR Analysis can be used to identify unknown materials, additives within polymers, surface contamination on a material, and more. How does IR spectroscopy work? Jul 7, Here is an example of an IR spectrum for formaldehyde. Related questions What does infrared spectroscopy measure?
What does infrared spectrum show in an IR? How does infrared absorption spectroscopy work? Their main disadvantages are slow response time and lower sensivity relative to other types of detectors. Thermocouple A thermocouple consists of a pair of junctions of different metals; for example, two pieces of bismuth fused to either end of a piece of antimony.
The potential difference voltage between the junctions changes according to the difference in temperature between the junctions. Several thermocouples connected in series are called a thermopile. Bolometer A bolometer functions by changing resistance when heated. It is constructed of strips of metals such as platinum or nickel or from a semiconductor. Pyroelectric detectors Pyroelectric detectors consists of a pyroelectric material which is an insulator with special thermal and electric properties.
Triglycine sulphate is the most common material for pyroelectric infrared detectors. Unlike other thermal detectors the pyroelectric effect depends on the rate of change of the detector temperature rather than on the temperature itself.
This allows the pyroelectric detector to operate with a much faster response time and makes these detectors the choice for Fourier transform spectrometers where rapid response is essential. Photoconducting detectors Photoconducting detectors are the most sensitive detectors. They rely on interactions between photons and a semiconductor.
The detector consists of a thin film of a semiconductor material such as lead sulphide, mercury cadmium telluride or indium antimonide deposited on a nonconducting glass surface and sealed into an evacuated envelope to protect the semiconductor from the atmosphere.
The lead sulphide detector is used for the near-infrared region of the spectrum. With increasing progress in new technology, samples in solution can now be measured accurately water produces a broad absorbance across the range of interest, and thus renders the spectra unreadable without this new technology.
Some instruments will also automatically tell you what a substance is by referencing it to a store of thousands of spectra held in storage. By measuring at a specific frequency over time, changes in the character or quantity of a particular bond can be measured. This is especially useful in measuring the degree of polymerisation in polymer manufacture or in identification of polymer degradation for example.
The progress of formation of an epoxy resin being hardened by an amine cross linking agent can be monitored by observing the appearance of a hydroxy group in the spectrum of a polymerising sample or by the disappearance of an epoxy group.
Modern research instruments can take infrared measurements across the whole range of interest as frequently as 32 times a second. This can be done whilst simultaneous measurements are made using other techniques. This makes the observations of chemical reactions and processes quicker and more accurate.
Infrared spectroscopy has been highly successful for applications in both organic and inorganic chemistry. A second type of IR spectrometer is a dispersive spectrometer.
The rotating mirror, M temporarily reflects the reference beam towards the machine optics whilst blocking the sample beam.
Reference beam and sample beam are alternately blocked and reflected. The thermocouple converts the different wavelengths of IR reaching it to a signal which is represented as a spectrum. The difference between reference and sample signals shows which parts of the spectrum have been absorbed by the sample. In the FT spectrometer, an interferometer is used instead of a diffraction grating.
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