Fourier Transform Infrared Spectrometer (FTIR)

1. hassan-alnajem
Fourier Transform Infrared Spectrometer (FTIR)
By : Hassan ALNAJEM
Alnajemhassan@gmail.com

2. Fourier Transform Infrared Spectrometer(FTIR)
hassan-alnajem
• FTIR: Fourier Transform Infrared Spectrometer

3. Why we use the FTIR?
hassan-alnajem
• We use FTIR to obtain the infrared spectra of various polymer and impurity in the
products like fish eyes and foreign particles.
• FTIR can use to:
1. Identify unknown materials.
2. Determine the quality or consistency of a sample.
3. Determine the amount of components in a mixture or compound.
4. Determination of co monomer content in polymers

4. What is FTIR and why is it significant ?
hassan-alnajem
FTIR is perhaps the most powerful tool for identifying types of chemical bonds (functional groups). By interpreting the infrare
d absorption spectrum the chemical bonds in a molecule can be determined. Unknown material can be identified by comparis
on to a library of known compounds. Because the strength of the absorption is proportional to the concentration FTIR can be
used for some quantitative analysis. Measurement can be done in the concentration range of few ppm to the percent level.

5. What is FTIR and why is it significant ?
hassan-alnajem
The term "infra red" covers the range of the electromagnetic spectrum between 0.78 and 1000 µm or 12800 to 10 cm-1
wavenumbers. In the context of infrared spectroscopy, wavelength is measured in "wavenumbers", which have the units cm-1.
wave number = 1 / wavelength in centimeters
It is useful to divide the infrared region into three sections; near, mid and far infrared;
The most useful I.R. region lies between 4000 - 670cm-1.
A typical FTIR Spectra is shown in figure-1
Figure 1: Typical FTIR Spectra
Advantages of FTIR

6. How FTIR Works:
FT-IR stands for Fourier Transform Infrared. In infrared spectroscopy, IR radiation is p
assed through a sample. Some of the infrared radiation is absorbed by the sample and some
of it is passed through (transmitted) producing a spectrum. The resulting spectrum represent
s the molecular absorption and transmission, creating a unique molecular fingerprint of the
sample. Like a fingerprint, no two unique molecular structures produce the same infrared sp
ectrum. This makes infrared spectroscopy useful for several types of analysis.
hassan-alnajem

7. How FTIR Works:
PARTS OF FTIR:
1) The Source
2) The Interferometer
3) The Sample Holder
4) The Detector
5) The Computer(Date recording)
hassan-alnajem

8. How FTIR Works:
1) The Source
Infrared energy is emitted from a glowing black-body source. This beam passes through an apertur
e which controls the amount of energy presented to the sample (and, ultimately, to the detector).
For Middle IR range air cooled silicon source is used while for near IR Tungsten Filament lamp is u
sed.
hassan-alnajem

9. How FTIR Works:
2)The Interferometer
The majority of the commercially available Fourier transform infrared instruments are based upon the Michelson
interferometer. It produces interference fringes by splitting a beam of monochromatic light so that one beam strikes a fixed
mirror and the other a movable mirror. When the reflected beams are brought back together an interference pattern results.
The resulting interferogram signal then exits the interferometer. Advantage of interferometer is because of moving mirror
mechanism it can scan for entire spectrum of IR frequencies in a single scan in a very short time.
hassan-alnajem

10. How FTIR Works:
3 )The Sample Holder
The beam enters the sample compartment where sample holder holds the sample.
Many type of sample holding accessories available. Mostly polymer analysis is being
done on sheet sample which can be hold in sample holder as stated in the figure
hassan-alnajem

11. How FTIR Works:
4 The Detector
The beam finally passes to the detector for final measurement. It consist of a thin film of a semiconductor material
, such a lead sulfide, mercury/cadmium telluride or indium atimonide. They must be cooled with liquid nitrogen to
minimize thermal noise. The detectors used are specially designed to measure the special interferogram signal.
hassan-alnajem

12. hassan-alnajem
Thank you
By : Hassan ALNAJEM
Alnajemhassan@gmail.com