Fourier transform infrared
spectroscopy
Berezin Danila
Moscow 2013
Plan of a journey
FTIR spectroscopy
And research
Its application
Terahertz radiation
Terahertz radiation is an electromagnetic waves
Terahertz gap
1011 – 1013 Hz
THz technology brings better sensing capabilities
Visible image
cancer
cavity
THz image
THz technology brings better sensing capabilities
Visible image
ceramic
knife
THz image
The goal is to measure how well a sample absorbs light
sample
light
Scanning spectroscopy is the most straightforward way
goal – spectrum
of absorption
absorption
It shines a monochromatic light beam…
beam source
sample
detector
absorption
…and measures how much is absorbed
beam source
sample
detector
FT spectroscopy is a less intuitive way to obtain the
same information
goal – spectrum
of absorption
absorption
A beam contains many frequencies of light at
once and absorption of that beam is measured
beam number
beam source
sample
detector
absorption
Next, beam is modified to give a second data point
beam number
beam source
sample
detector
absorption
Process is repeated many times
beam number
beam source
sample
detector
Afterwards, computer processing is required
There are still undiscovered nuances
How to generate and modify that
special beam?
What computer processing is
required?
Wave interference is a key to generate that special beam
Michelson interferometer
light source
moving mirror
beam for the
experiment
Processing required is Fourier transform
raw data
desired result
FT spectroscopy has an advantage – Fellgett’s advantage
Scanning
spectroscopy
Fourier transform
spectroscopy
FTIR spectroscopy
– Possible applications
– Technology
– Advantage
Thank you
Back up
Fourier transform
mirror 1
Monochromatic source
y1/2
x/2
mirror 2
Fourier transform
Polychromatic source
Fourier transform