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

Evaluate kinetic energy in oscillation, How many times the kinetic energy r...

How many times the kinetic energy reach at minimum and maximum point during one oscillation?

Calculate the magnitude of the induced field, A long solenoid has a diamete...

A long solenoid has a diameter of 10.4cm. When a current I exists in its windings, a uniform magnetic field of magnitude B=37.7 mT is produced in its interior. By decreasing I, the

The fundamental particles, The fundamental particles: Although other at...

The fundamental particles: Although other atomic particles are known, the three fundamental ones are: Protons. The proton has unit mass and carries a unit positive charge.

Is this wavelength in vacuum, Is this wavelength in vacuum? Answer; as ...

Is this wavelength in vacuum? Answer; as per mass of CPH is constant, and Vc is for an alone CPH, so wavelength should be in vacuum, that there is not any gravity effect. But i

Driving nails with the help of inertia, Driving nails with the help of iner...

Driving nails with the help of inertia Extend a thin board over the edge of a table and support it well by having someone stand on the part in excess of the table. Try to drive

Magnetic field lines of a stationary bar magnet, Indicate all that is incor...

Indicate all that is incorrect about the statement The magnetic field lines of a stationary bar magnet move from the north pole of the bar magnet to the south pole of the bar magne

Kinematic, A sprinter runs 100.0 m. If he travels at constant acceleration ...

A sprinter runs 100.0 m. If he travels at constant acceleration of 1.95 m/s2 for the first 6.00 s, and then at constant velocity for the remaining time, what was his average veloci

Vector, If A=3i+j+3k, B=-2i-4j-3k and c=2i+4j+3k. Find a unit vector parall...

If A=3i+j+3k, B=-2i-4j-3k and c=2i+4j+3k. Find a unit vector parallel to 3A-2B+4C

Setellite, Discusse about motion of satellite

Discusse about motion of satellite

Explain optical interference process, Optical interference process is broad...

Optical interference process is broadly divided into two categories namely (i) division of wave front (ii) division of amplitude. Give one example for each category of interference

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