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

Keplers second law, Keplers Second Law After studying a wealth of plane...

Keplers Second Law After studying a wealth of planetary data for the motion of the planets about the sun, Johannes Kepler reasons three laws of planetary motion. Kepler's secon

What is natural physics, Explain natural physics concerned about? Soluti...

Explain natural physics concerned about? Solution:  Natural physics is the branch of physics which deals the physics related to nature.For example-physics related to sunlight,re

How to calculate n factor of disproportion reaction, How to calculate n fac...

How to calculate n factor of disproportion reaction? Total number of electron change divided by no. of moles of reactant This is conventional method Total electron chan

Motion, to draw v-t graph with variable retardation

to draw v-t graph with variable retardation

Uses of radio isotopes, Uses of radio isotopes: Used in i)Medicine ...

Uses of radio isotopes: Used in i)Medicine ii) Industry iii) Agriculture iv) Meteorology and v) Radio active dating.

Gravitational force, A body of mass 2 kg thrown vertically upwards with a v...

A body of mass 2 kg thrown vertically upwards with a velocity 40 m/s comes to instantaneous rest at a height 50 m. Is there any other force (other than gravitational force), if yes

What is an illuminator, What is an illuminator? An illuminator, light g...

What is an illuminator? An illuminator, light generator or source is a box along with a lamp inside, pointing in the direction of an opening where fiber optics is secured. Obvi

Current electricity, if electrons are moving from east to west in a conduct...

if electrons are moving from east to west in a conductor is there a flow of current?

Subset [tabular method], 1.A=the set of whole numbers less tan 4 ? 2.B=the ...

1.A=the set of whole numbers less tan 4 ? 2.B=the set of prime numbers less than 19 ? 3.C=the set of first three days of week?

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