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Method Description

IR spectroscopy is a physical method of analysis, which works with infrared light (800-500,000 Nm). During the irradiation of a material with electromagnetic waves certain frequency ranges are absorbed. Infrared radiation lies energetically in the range of the oscillation levels of molecular bonds. The absorption leads to a vibration stimulation of the molecular bonds. They are visible in the form of excursions in the measured spectrum (diagram). Since the energies and/or frequencies necessary for it are characteristic of the respective connections, materials can be identified in such a way. The IR spectroscopy is thus structural clarifying. Molecule oscillations of certain atomic groups within the range of 4000-1500 cm-1 are particularly characteristic, therefore the IR spectroscopy is suitable for the determination of the functional groups of the examined molecule. Additionally the entire spectrum offers and particularly the finger print range (of 1500-600 cm-1) often valuable reference points for identification.

Conditions of IR-Spectroscopy

IR spectroscopy is used for the quantitative determination of known substances (inorganic and organic), their identification on the basis a reference spectrum or for the structure elucidation of unknown substances.


The IR spectroscopy is accomplished by partners of the ZEA-3. Several devices with the following measuring methods are available:


The sample is pressed as powder in KBr and measured afterwards.

Reflexion and Absorption (IRAS)

Here the IR radiation is sent nearly parallel onto the sample. With this measuring method the intensity is much lower than with the transmission. This technique is particularly suitably for layer systems/coatings.

Attenuated total reflection (ATR)

With ATR spectroscopy the radiation in a fibre optic is led in total reflexion. An evanescent field at the surface of this fibre optics is generated, which interacts with the sample. This method is suitable for solid and liquid samples.


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