Population inversion, Physics

Assignment Help:
population inversion
  • The process in which the number of electrons (N2) in a higher energy state called ‘metastable state of an active medium is increased to a value greater than the number of electrons (N1) in the ground state (i.e.N2 > N1) is called population inversion.
  • There are certain special substances or systems in which the electrons, once excited can remain in the higher energy state for longer times.
  • Such systems are called Active systems or Active Media.
  • Active systems are generally compounds or mixtures of different elements.
  • Consider three electronic states 1,2,3, in an active medium. (Refer text book for diagram.
  • Normally Large number of electrons exist in the Lowest energy state called ground state.
  • Let this number be N1 when photons of energy equal to the difference between E3 and E1 are incident, the electrons from state (1) are excited to state (3) because of absorption. But the property of the state (3) is such that the life time of electrons
  • in the state is very short, of the order 10-8 seconds. 
  • Of course most electrons return to state (1) from state (3) by spontaneous emission, but some electrons go to state (2) also.
  • Therefore, the electrons from the state (3) undergo a quick transition to the state (2) by emitting only a small energy (E3 - E2) which is simply absorbed as the thermal energy by the medium itself.

Related Discussions:- Population inversion

Explain the basic concept of sonar, Explain the basic concept of sonar. ...

Explain the basic concept of sonar. Basic concept of SONAR: Sonar is based ontpo the echo-sounding technique of ultrasound. While an ultrasonic wave is transmitted by water,

Explain radio waves, Radio Waves: Radio waves are electromagnetic waves...

Radio Waves: Radio waves are electromagnetic waves with large range of wavelength from a few millimetres to many meters.

Caluclate the work done by machine, A certain machine exerts a force of 200...

A certain machine exerts a force of 200 Newton on a box whose masses 30 kilograms.  The machine moves the box a distance of 20 meters with a horizontal floor. What amount o

MRI MACHINE, WHY HEATER IS KEPT IN CONTROL ROOM OF MRI? IS IT KEPT ON ALL T...

WHY HEATER IS KEPT IN CONTROL ROOM OF MRI? IS IT KEPT ON ALL THE TIME OR IT CAN BE TURNED OFF AT NIGHT AND RESTARTED AT MORNING

What are the components of endoscope, What are the components of endoscope?...

What are the components of endoscope? An endoscope can consist of following components • A rigid or flexible tube • A light delivery system to clarify the organ or object

What are the advantages of fibre optic communication, What are the advantag...

What are the advantages of fibre optic communication? Advantages of fibre optic communication are as follows: a. Enormous band width Coaxial cable transmission of 500 M

Define collisions, When two particles tend to each other, their motion alte...

When two particles tend to each other, their motion alters or their momentum modify because of their mutual interactions. This phenomenon is called as collision. During collision

Nicols prism, give full detail of nicols prism about 20 to 30 pages

give full detail of nicols prism about 20 to 30 pages

Physics question with infinite nonconducting uniform, Physics question with...

Physics question with infinite nonconducting uniformly charged planes? Two infinite non conducting uniformly charged planes lie parallel to each other and to the yx plane. One is

Write Your Message!

Captcha
Free Assignment Quote

Assured A++ Grade

Get guaranteed satisfaction & time on delivery in every assignment order you paid with us! We ensure premium quality solution document along with free turntin report!

All rights reserved! Copyrights ©2019-2020 ExpertsMind IT Educational Pvt Ltd