FTIR

1. FOURIER TRANSFORM INFRARED
PRESENTED BY
Gritta Sebastian
Ist M.Pharm
Dept. of Pharmaceutics
JSS University
College of pharmacy
Mysore

2. IR instruments can be classified as:
1.Dispersive instruments
• Single beam IR spectrophotometer
• Double beam IR spectrophotometer
2.Non-Dispersive instruments
• Fourier transform infrared (FTIR) spectrometer

4.  Fourier Transform Infrared (FT-IR) Spectroscopy
is a modern tool to study the characteristics of
molecules, either in solid, liquid or gas phase.
 An FTIR spectrometer simultaneously collects
spectral data in a wide spectral range.
 The term Fourier transform infrared
spectroscopy originates from the fact that a
Fourier transform (a mathematical process) is
required to convert the raw data into the actual
spectrum.

5. FTIR V
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
 It is mechanically simple with only one moving part

6.  IR radiation source
 Beam splitter
 Fixed mirror
 Moving mirror
 Helium-Neon laser
 Collimating mirrors
 Sample holder
 Detector

7. FTIR seminar
FT Optical System Diagram
Interferometer
He-Ne gas laser
Fixed mirror
Movable mirror
Sample chamber
Light
source
(ceramic)
Detector
(DLATGS)
Beam splitter

8.  Radiations from the source falls on the interferometer
 It comprises of beam splitter, moving mirror, fixed mirror
 The beam splitter splits the light into two half beams of
equal intensities
 One half of the beam is passed to the fixed mirror
 Other half is directed towards the mirror
 It moves at short distance away from the beam splitter at
constant speed

9.  Light enters the spectrometer and is split by the
beam splitter. The figure above shows what is
referred to as the Michelson interferometer
 Speed of the moving mirror is controlled by using a
helium-neon laser beam
 Because of the steady movement, detector
receives constants signals of maxima & minima
 Beams after undergoes reflection from the
respective mirrors are recombined & send signal to
the detector

11.  Combined signal is called as interferogram
 After that the interferogram is either transmitted
or reflected to the sample cell
 Samples absorbs only those IR frequencies which
cause vibration within the sample molecules
 The signal is transmitted to the detector where it
gets measured
 The coded signal were decoded by using computer
 Technique is called as Fourier Transformation

12.  Filtration of radiation from the source is not
required
 The data can be stored and reanalyzed
 Enhanced frequency reproducibility
 Enhanced frequency resolution
 Less time consuming

13.  Expensive
 Required precision for mirror movement
 Detection of the sample is influenced by
water vapour, path length & chemical
interference

14.  Opaque or cloudy samples
 Trace analysis of raw materials or finished
products
 Kinetics reactions on the microsecond time-scale
 Analysis of chromatographic and
thermogravimetric sample fractions

15.  Instrumental methods of chemical analysis;
Gurdeep R. Chatwal;
Page no: 2.41-2.53
 Pharmaceutical analysis-II
Shahla Fatima &Ayesha Parveen
Page no:3.8-3.11
 Pharmaceutical analysis
O.V.K.Reddy
Page no:1.681.72

16.  Introduction to Fourier Transform Infrared Spectrometry
www.thermonicolet.com
 Principles of instrumental analysis;
2nd edition
Dougles skoog & Donald .M.West
Page no:210-219