FT-IR is an instrument with abilities of characterization of matters in elemental analysis using wavelength of functional groups. this seminar is based on the instrument FT-IR, describing its purpose, advantage and sailent features.

1. Ethiopian institute of textile and fashion technology
Physical properties of textile fiber
Seminar on
Fiber characterization by FT-IR
To: ass. Prof. Adane haile
By: seblewongel petros

2. Contents
• Introduction
• Theoretical background
• Principles and Procedures of FT-IR
• Data analysis and interpretation
• Characterization of fibers
• Summary
• References

3. Introduction
• spectroscopic approaches have been widely used to distinguish the broad
categories of fibers
• IR spectroscopy is the only analytical method which provides
ambient temperature operation
directly monitor the vibrations of the functional groups
characterize molecular structure and govern the course of chemical
reactions.
measuring the intensity of infrared radiation as a function of frequency or
wavelength.

4. Cont…
• advantages of FT-IR over dispersive instruments such as:
 high speed data collection,
increased resolution,
lower detection limits and
greater energy throughput

5. Sailent features of FT-IR
• non-destructive technique
• precise measurement method with no external calibration
• collecting a scan every second
• Finger print analysis
• It has greater optical throughput
• It is mechanically simple with only one moving part

6. Theoretical background

7. Atoms movement
electronic, translational,
rotational vibrational

8. Cont…
Until 1800s, IR was not
recognized as a distinct part
of the electromagnetic
spectrum.
Most IR instrumentation
used through the 1970s was
based on prismor grating
monochromators.
A major breakthrough in IR
spectroscopy was the
introduction of FT-IR
spectrometers.
which uses an instrument
called interferometer that was
discovered almost a century
ago by Albert Michelson.

9. FT-IR
• designed by Michelson in 1891.
• Followed by complexity of the calculation required to transform the
measured data into a spectrum.
• Fast Fourier Transform algorithm by James Cooley and John Tukey
(1964),

10. Cont…
• Discrete fourier formula
• Where
• x is the sample spacing. S(k s ) is the intensity of
the the signal with wave number k . The spacing
in the spectrum is related to x by =1
• Nx where N is the number of measurements.

12. Principles of FT-IR
The principles of fourier
transform IR spectroscopy is that
interpreting the IR source that
will be transmitted through or
absorbed by the sample to
readable property of the sample.

13. The Interferogram
consists of two mutually perpendicular
plane mirrors,
one of which can move along the axis that
is perpendicular to its plane
In between the fixed and the movable
mirror is a beam splitter.
Device that ideally, allows 50% of light to
pass through to the movable mirror while
reflecting the other 50% to the fixed mirror.

14. How does it work

15. Procedures of FT-IR
Source:
• energy is emitted from a
glowing black-body source.
Interferometer:
• where the “spectral encoding” takes place.
Sample:
• This is where specific frequencies of energy are
absorbed.
Detector:
• The beam passes to the detector for final measurement.
Computer:
• where the Fourier transformation takes
place.

16. Data Analysis
• The interferogram is a function of time whereas a spectrum is a function of
frequency (or wavelength).
• To produce a spectrum we compute the cosine Fourier Transform of the
Interferogram.
• The principle behind Fourier Transforms is that any wave (or periodic function) can
be expressed as a sum of cosine and sine functions (a Fourier Series).
• Spectra that have been measured on FT-IR spectrometers consist of a string of
intensity values at equally spaced intervals.

17. Cont…
• Automated peak picking involves two steps:
(1) the recognition of peaks, and
(2) the determination of the wavenumber values of maximum absorbance.
• Spectral features in the infrared spectral region frequently result from the
overlap of two or more bands.

18. • Different regions of the infrared

19. Finger print analysis
• a functional group may have multiple-characteristic absorption peaks,
especially for 1500 –650 cm-1, which is called the fingerprint region.
• It usually contains very complicated series of absorption.
• Each different compound produces different pattern of troughs in this part
of the spectrum.

20. Cont…

21. Characterization of cotton
• Cellulose occurs in the form of long, slender chains, polymer of 1-4 linked ß-D-
glucose.
• Hydroxyl groups in C2, C3 and C6 contribute to the formation of various kinds of
inter- and intra-molecular hydrogen bonds.
• hydrogen bonds contribute about 20% the strain energy to the cellulose.
• plays an important role in the mechanical properties of the cellulose.
• FTIR is more advanced tool to study hydrogen bonds in cellulose.

24. Characterization of polyester
• Analysis of PET fiber using FTIR has been performed by many researchers.

27. Characterization of silk
• Synchrotron FTIR (s-FTIR) microspectroscopy was used to monitor the
silk protein conformation in a range of single natural silkfibers (domestic
and wild silkworm and spider dragline silk).
• With the selection of suitable aperture size, we obtained high-resolution S-
FTIR spectra capable of semiquantitative analysis of protein secondary
structures.

28. Ftir reading of animal silk
single silkfibers:
(a)B. mori (Bombyx mori),
(b) A.pernyi (Antheraea pernyi),
and
(c) N. edulis (Nephila edulis).

29. Cont…
• the broad peak centered at 1655 to 1660
cm1 random coil, helical conformation,
or both;
• the peak from 1620 to1630 cm1to β-
sheet conformation; and
• the small peak from1690 to 1700 cm1
toβ-turn conformation of the hairpin-
folded antiparallelβ-sheet structure

30. Summary
• FT-IR spectroscopy is very reliable and sensitive technique for
identification of very broad range of samples. Even though its
essentials were discovered almost 200 years ago, it became widely
used only in the last 50 years.
• The main reason for its popularity is the existence and affordability of
powerful computers and fast computational algorithms which also
enabled the development of variety of applications for FT-IR
spectroscopy in different areas of science and industry.

31. References
• Synchrotron FTIR Microspectroscopy of Single Natural Silk Fibers Shengjie
Ling,Zeming Qi,David P. Knight,Zhengzhong Shao,and Xin
Chen,Department of Macromolecular Science, Laboratory of
AdvancedMaterials, Fudan University, Shanghai, 200433, China
• Fourier transform infrared (FTIR) spectroscopy, Catherine Berthomieu &
Rainer Hienerwadel, Published online: 10 June 2009.
• Fourier Transform Infrared Spectrometry ,Peter R. Griffiths and James A. de
Haseth:, Second edition, John WIley and Sons, Hoboken, New Jersey, 2007.

32. Thank you