The advantages offered by FT- IR spectrometers over earlier dispersive instruments were highlighted in the earlier article. In the present article the system design features that contribute to such advantages are briefly discussed
High speed of analysis – the advantage of speed is realized because all the wavelengths in the spectral range are scanned simultaneously and absorption spectra are displayed in real-time.
Absence of slits and gratings – absence of energy limiting elements makes possible availability of entire incident beam energy at any given point of time. Further due to high scan speeds several spectra can be co-added and signal averaging results in several fold improvement of sensitivity
Simultaneously modulation of frequencies – as the Michelson interferometer modulates all the available frequencies simultaneously there is no equivalent of stray light which contributes to spectral discreetness.
Inbuilt wavelength calibration – the system uses an inbuilt He-Ne laser which is used to internally auto calibrate the individual frequencies to accuracies better than 0.01 cm -1. However, it is still advisable to run the reference polystyrene film spectra from time to time and compare with the standard spectra stored in reference library at time of installation.
Absence of moving components – absence of moving components except the moving mirror minimizes wear and tear.
Absence of Grating or slit programs – ensures consistency of resolution and absence of any discontinuities throughout the spectral range
Spectral overlay feature – assists in comparison with standard reference spectra stored in commercially available spectral or in-house libraries.
High sensitivity inherent to the technique permits effective use of accessories such as diffuse reflectance accessory, horizontal ATR, specular reflectance accessory, gas cells, etc which makes FT-IR a reliable, versatile and rapid method for material characterization.
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