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  1. The entire range of electromagnetic radiations is called as electromagnetic spectrum. It consists of different type of radiations: ϒ-rays, X-Rays, Far UV (Vacuum UV), Near UV, Visible, Near IR and IR, Far IR, Microwave and Radiowaves.  From ϒ-rays to radiowaves the wavelength is increases and decrease the energy.

Type of radiations

Frequency (v) Hz

Wavelength (λ)

Wave number

Energy (E) eV

ϒ-rays

˃3x1019

˂10-2 Ao

˂100 Ao

˃105

X-Rays

3x 1017 to

3x 1019

10-2 to 10+2 Ao

100 to 0.01 Ao

103 to 105

Far  UV (or vacuum UV) Near UV

7.5 x 1014 to

3 x 1017

100 to 200 nm

200 to 400 nm

  1. to 5 x 10-3 nm

5 x 10-3 to

2.5 x 10-3 nm

3 to 103

Visible

4.3 x 1014 to 7.5x1014

400 to 780 nm

2.5 x 10-3 to 1.28 x 10-3 nm

2 to 3

Near IR

MID IR

FAR IR

3 x 1012 t0 4.3x1014

0.78 to 2.5 nm

2.5 to 50nm

50 to 100 nm

1.28 to 0.4 nm

0.4 to 0.02 nm

0.02 to 0.001 nm

0.01 to 2

Microwaves

3 x 109 to 3x1012

0.1 to 100cm

 10 to 0.01cm

10-5 to 0.01

Radio waves

˂3 x 109

1 to 1000m

1 to 10-3

˂10-5

The following are the electromagnetic source and transitions involved in the sample on exposure to electromagnetic radiation.

Type of radiation

Radiation source

Transitions Involved

ϒ-rays

Radio nuclides (Cobalt -60, cesium - 137)

Nuclear transitions

X-Rays

Coolidge tube

Nuclear transitions (inner electron)

Far  UV (or vacuum UV) Near UV

Deuterium  lamp

Electronic , Vibrational and rotational transitions

Visible

Tungsten lamp

Near IR

MID IR

FAR IR

Tungsten, dye laser

Nerst  glower, globar source etc

Vibrational and rotational transitions

Microwaves

Reflex klystron

Electron spin flip rotational transitions

Radio waves

Magnetron tube

Nuclear electron flips

 

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