Fourier transform infrared spectroscopy (FTIR) is a technique that collects infrared spectral data to identify chemical bonds in molecules. It works by passing infrared light through a sample and measuring the vibrations of chemical bonds which produce a unique molecular "fingerprint" spectrum. FTIR provides advantages over other infrared techniques by being faster, more sensitive, and able to analyze a wider spectral range simultaneously. It is widely used for applications like polymer identification, contamination analysis, and biomedical research.

1. Fourier transform infrared spectroscopy
Presented by:
IQRA MALIK
Presented to:
Dr. Mohsin Ali Raza
Department of Metallurgy
and Materials Engineering ,
CEET
University of the Punjab

2.  Fourier transform infrared spectroscopy (FTIR) is a
technique which is used to obtain an infrared spectrum
of absorption, emission, photoconductivity or Rama
scattering of a solid, liquid or gas.
 An FTIR spectrometer simultaneously collects spectral data
in a wide spectral range
 Fourier Transform Infrared Spectroscopy (FTIR) is a
powerful tool for identifying types of chemical bonds
in a molecule by producing an infrared absorption
spectrum that is like a molecular "fingerprint"

3. Around 1800, Herschel studied the
spectrum of sunlight using the prism.
He measured the temperature of each
color, and found the highest
temperature was just beyond the red,
what now we call the ‘infrared’.
Developmental background

4.  Infrared radiation lies between the visible and microwave
portions of the electromagnetic spectrum
 Infrared waves have wavelengths longer than visible and
Shorter than microwaves and have frequencies which are lower
than visible and higher than microwave
 The infrared region is divided into near(closer to visible
light),far(closer to microwave) and mid regions(b/w these two)
 Primary source of IR is thermal radiation(heat)
 Any object radiates in infrared. Even an ice cube emit
infrared.
What is Infrared Radiation

5. The heart of FTIR is Michelson Interferometer

6. The basic Michelson Interferometer consists of
 a broad-band light source which emits light covering
the mid-IR range,
 a beam splitter made of KBr or CsI,
 Two front surface coated mirrors – one moving and
one fixed, and
 a detector.
THE MICHELSON INTERFEROMETER
Working principle:
Light falls on a light source
Some of the light is reflected some
transmitted
 The reflected light goes to the fixed
mirror and it reflected back to beam
splitter and the transmitted light also
reflected to beam splitter
 Both goes to detector and both
interfere constructively and destructively
and generate sinusoidal signal and
generate interferrogram.

8. Fourier transform infrared spectroscopy is preferred over
dispersive or filter methods of infrared spectral analysis for
several reasons:
 It is a non-destructive technique
 It provides a precise measurement method which requires no external
calibration
 It can increase speed, collecting a scan every second
It can increase sensitivity – one second scans can be co-added together to
ratio out random noise
 It has greater optical throughput(because it do not require slits to achieve
resolution).
 It is mechanically simple with only one moving part in a compound
FTIR instruments are computerized which makes them faster and more
sensitive than the older dispersive instruments
FTIR AND DISPERSIVE IR
SPECTROMETRY

9. Dispersive Spectrometer FTIR
In order to measure an IR
spectrum
It takes several minutes
The detector receives only a few
% of the energy of original light
source.
In order to measure an IR
spectrum
FTIR takes only a few seconds
The detector receives up to 50%
of the energy of original light
source (much larger than the
dispersion spectrometer )

11. The normal instrumental process is as follows:
The Source:: Infrared energy is emitted from a glowing black-body source.
The Interferometer: The beam enters the interferometer where the “spectral
encoding” takes place.
 The Sample: The beam enters the sample where it is transmitted through or
reflected off the surface of the sample, depending on the type of analysis being
accomplished.
 The Detector: The beam finally passes to the detector for final measurement.
The detectors used are specially designed to measure the special interferrogram
signal
 The Computer: The measured signal is digitized and sent to the computer
where the Fourier transformation takes place. The final infrared spectrum is then
presented to the user for interpretation and any further manipulation.

12. Sampling techniques
1. Liquid samples
Neat sample
Diluted solution
Liquid cell
2. Solid samples
KBR pellets
Neat sample
Pressed films
3. Gas samples
Short path cell
Long path cell

13. • It can identify unknown material(both
organic or inorganic).
• It can identify quantity or consistency of
sample.
• It can identify the amount of components
in a compound
What Information FTIR
provides

14.  The term Fourier Transform Infrared Spectroscopy
(FTIR) refers to a fairly recent development in the manner in
which the data is collected and converted from an interference
pattern to a spectrum. Two types of analysis involve are:
Qualitative analysis:
 FTIR can be used to identify chemicals from paints, polymers,
coatings, drugs, and contaminants.
 It can identify chemical bonds (functional group)
Chemical bond in the spectra can be
determined by interpreting the infrared
spectrum
Chemical bond in the spectra can be
determined by interpreting the infrared
spectrum

16. Quantitative Analysis
Type of Analysis
Incoming material analysis for product quality control

17. • Incoming raw material matched to previously used production sample…
• Raw material analyzed kept in storage for future analysis…

18. Chemical Analysis:
Match spectra to known databases
i.e. identify an unknown compound
Unknown Green Contaminant
found in production line…
Spectra obtained by FTIR Analysis….

19. FTIR Green Contaminant Polymer Library
Match….
i.e. Green Contaminant – Polyamide 6,6 material…

20. Structural Ideas: Can determine what chemical groups are in a specific
compound.

21. APPLICATIONS
Determination of degrees of crystallinity in polymers (e.g
LDPE and HDPE)
Extent of thermal, UV or other degredation
or depolymarization of polymers and paint coatings
Can also be used on satellites to probe the space
Thin film analysis , contamination analysis
In remote sensing, in parmaceuticals

22. •Universal technique
•sensitivity 10-6 grams
•fast and easy
•relatively inexpensive
•rich information
•sensitive to “molecules”-anything that contains
chemical bonds
•vast majority of molecules in the universe
absorb mid-infrared light, making it a highly
useful tool
Advantages of FTIR (technique)

23. Cannot detect atoms or monoatomic ions
- single atomic entities contain no
chemical bonds
Cannot detect molecules comprised of
two identical atoms symmetric-such as N2
or O2.
Aqueous solutions are very difficult to
analyze- water is a strong IR absorber
Complex mixtures - samples give rise
to complex spectra
Disadvantages of FTIR

24. Conclusion:
Infact it is the preferred method of spectroscopy so it is used for many
future applications. FTIR spectroscopy is a powerful tool for
biomedical and biological applications in future and is used for cancer
detection.It produces hydrated polymer coating used to make contact
lens and is also used for drug analysis and also has many applications in
biochemical, food and agriculture.