Brief introduction to Fourier transform infrared spectrometry

2 Brief introduction to Fourier transform infrared spectrometry 

Infrared spectroscopy measures the light absorbed by different types of vibrations in molecules. 

Infrared radiation from the light source is divided into two beams by the beam splitter. One beam is reflected onto a moving mirror and the other onto a stationary mirror. Both beams are then recombined and pass through the sample to the detector. Fourier transformation of the resulting interferogram yields an infrared transmission spectrum. 

In TGA-FITR, the absorption bands of each spectrum are usually simultaneously integrated over the entire spectral range or over characteristic spectral regions. The intensity is presented as a function of time as so-called Gram-Schmidt curves or chemigrams. 

The TGA is coupled to the MS using a fused silica capillary tube heated to 200°C to prevent condensation. Often just a small fraction of the evolved gas is taken into the mass 

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