Spectroscopy and Electromagnetic Spectrum – Instrumental Methods of Analysis B. Pharma 7th Semester

Spectroscopy and Electromagnetic Spectrum

Session Objectives

By the end of this
session, students will be able to:

Ø  Explain
the salient features of Electro Magnetic Spectrum

Ø  Outline
the parameters for identification and distinction of different Electromagnetic
radiations

Spectroscopy

       Spectroscopy
is the study of the way light (electromagnetic radiation) and matter interact.

       There
are a number of different types of spectroscopic techniques

       The
basic principle is to pass a beam of a particular electromagnetic radiation
through a sample and observe how it responds to such a stimulus; allowing
scientists to obtain information about the structure and properties of matter.

Electromagnetic
radiation

Electromagnetic
Spectrum

The electromagnetic spectrum comprises of waves of
electromagnetic radiation

The systematic display of whole range of EM wave frequencies
is called the electromagnetic spectrum.

Different parts interact with matter in different ways. 

The frequencies humans can see are called visible light, a
small part of the whole spectrum.

Visible light

Color

Wavelength

Violet

400-420 nm

Indigo

420-440 nm

Blue

440-490 nm

Green

490-570 nm

Yellow

570-585 nm

Orange

585-620 nm

Red

620-780 nm

 

 

What are
electromagnetic waves?

       How
electromagnetic waves are formed

       How
electric charges produce electromagnetic waves

       Properties
of electromagnetic waves

Electromagnetic
Waves…

       Do
not need matter to transfer energy.

       Are
made by vibrating electric charges and can travel through space by transferring
energy between vibrating electric and magnetic fields.

How do moving charges
create magnetic fields?

       Any
moving electric charge is surrounded by an electric field and a magnetic field.

What happens when
electric and magnetic fields change?

       A
changing magnetic field creates a changing electric field.

       One
example of this is a transformer which transfers electric energy from one
circuit to another circuit.

       In
the main coil changing electric current produces a changing magnetic field

       Which
then creates a changing electric field in another coil producing an electric
current

       The
reverse is also true.

Making
Electromagnetic Waves

       When
an electric charge vibrates, the electric field around it changes creating a
changing magnetic field.

       The
magnetic and electric fields create each other again and again.

       An
EM wave travels in all directions.  The
figure only shows a wave traveling in one direction.

       The
electric and magnetic fields vibrate at right angles to the direction the wave
travels so it is a transverse wave.

SUMMARY

       Spectroscopy
is the study of the way light (electromagnetic radiation) and matter interact.

       The
systematic display of whole range of EM wave frequencies is called the electromagnetic
spectrum

       Electromagnetic
radiation includes ϒ
radiation, x –rays, UV – Visible, IR radiations, Microwaves and radio waves.

 For Detailed

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