Spectroscopy is the study of the interaction between electromagnetic radiation and matter such as atoms, molecules, or ions. It uses electromagnetic radiation of specific wavelengths or wavelength ranges to qualitatively or quantitatively analyze matter. Spectroscopy deals with absorption, emission, and scattering of electromagnetic radiation when it interacts with matter. The interaction depends on the energy of the radiation, with more energetic radiations like UV and x-rays potentially causing electron ejection, and less energetic ones like infrared inducing molecular vibrations or microwave causing molecular rotation. Spectroscopy is widely used to study the internal structure of organic and inorganic compounds and has advantages like being non-destructive, sensitive, and requiring small sample sizes.

1. INTRODUCTION TO
SPECTROSCOPY
Dr. Divya Dinesh
Department of Chemistry
T.K.M.M.College

2. Spectroscopy
• Spectroscopy is the study of the interaction between
electromagnetic radiation and matter.
• The matter can be atoms, molecules or ions
• It is a branch of Science in which electromagnetic radiation of
particular wavelength or range of wavelength is used for
qualitative or quantitative of matter
Matter:
• Anything which occupies space in universe and having mass

3. Electromagnetic radiation
• Is a form of energy and has both electrical and magnetic characteristics
• The electric and magnetic fields in electromagnetic wave oscillate along
directions perpendicular to the propagation direction of the wave
• E = hν and c = λν where ‘ν’ is pronounced as ‘nu’

4. Electromagnetic Spectrum

5. • Frequency :-
number of waves produced each second (measured in Hz).
• Wavelength (λ) :-
the distance between two successive waves (measured in m).
• Amplitude :-
is the maximum distance a wave extends beyond its middle position.
Wavenumber (ν) :-
the reciprocal of wavelength (measured in m-1).
Properties of a wave

6. Applications of spectroscopy
Extensively used to study the internal structure of matter, especially molecules
of complex organic and inorganic compounds
Advantages:
Less time consuming
Extremely sensitive
Cost effective in long run
Very small amount of sample is required
non-destructive method, so entire sample can be recovered
Highly reliable in establishing the identity of two compounds and provide
more information about molecular structure

7. Spectroscopy deals with the interaction of electromagnetic radiation with matter

8. Absorption – Ground State to excited state
Emission – excited state to ground state
Absorption spectroscopy
Emission spectroscopy

9. The nature of the interaction between radiation and
matter may include-
1. absorption
2. emission
3. scattering ……..
They help in the study of matter with respect to
1. qualitative study
2. quantitative study

10. Interaction with matter...
• The effect of electromagnetic radiation on interaction with matter
depends on energy associated with the radiation
• Very energetic radiations (UV and x-ray) may cause an electron to be
ejected from the molecules
• Radiation in the infrared region of the spectrum have much less energy
they can cause vibrations in molecules
• Microwave radiation is even less energetic than infrared radiation it can
neither induce electronic transition in molecules nor can it cause
vibrations it can only cause molecules to rotate
• Ultraviolet, visible - electronic transitions
• Infrared - molecular vibrations
• Microwave - molecular rotation