Name - Jadhav Avinash J
Roll no - 2K13E11
SavitriBai Phule Pune University
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Contents
 Electromagnetic spectrum
Definition
Diagram
Light absorption
Electronic excitation
Application
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WHAT IS SPECTROSCOPY?
Atoms and molecules interact with electromagnetic
radiation (EMR) in a wide variety of ways.
Atoms and molecules may absorb and/or emit EMR
Absorption of EMR stimulates different types of motion
in atoms and/or molecules.
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•The patterns of absorption (wavelengths absorbed and to
what extent) and/or emission (wavelengths emitted and their
respective intensities) are called ‘spectra’.
•The field of spectroscopy is concerned with the
interpretation of spectra in terms of atomic and molecular
structure (and environment).

ELECTROMAGNETIC SPECTRUM
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UV-Visible Instrumentation
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UV-Visible Instrumentation
Light source
Deuterium and hydrogen lamps
Sample containers
Cuvettes
 Plastic
 Glass
 Quartz
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BEER-LAMBERT LAW
For a light absorbing medium, the light intensity falls
exponentially with sample depth.
For a light absorbing medium, the light intensity falls
exponentially with increasing sample concentration.
100% x
I
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T
o
t
o
t

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
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==
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Io It
l
cuvette
Sample depth

BEER-LAMBERT LAW
clA
It
I
A
λε=
=
0
log
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BEER-LAMBERT LAW
limitations
• Polychromatic Light
• Equilibrium shift
• Solvent
• pH
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Electronic transitions
Electronic transitions
Molecular Orbital
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Application
Ultraviolet radiation stimulates molecular vibrations and
electronic transitions.
Absorption spectroscopy from 160 nm to 780 nm
Measurement absorption or transmittance
Identification of inorganic and organic species
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