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

Units and measurement.., the unit of force and length are doubled, the unit...

the unit of force and length are doubled, the unit of energy will be

Resolution of forces, Resolution of Forces: This topic is important, bu...

Resolution of Forces: This topic is important, but is really the opposite to Addition of forces. Recalling that two forces can be added to give a single force known

Thermodynamics, according to the first law of thermodynamics , obtain the r...

according to the first law of thermodynamics , obtain the relationship between specific hears of gases

Conservation of energy, CONSERVATION OF ENERGY 1.   Potential energy ...

CONSERVATION OF ENERGY 1.   Potential energy is, as the word suggests, the energy "locked up" up somewhere and which can perform work. Potential energy Potential energy can b

Newtons laws skydiving, Newtons Laws Skydiving Assume the motion of the...

Newtons Laws Skydiving Assume the motion of the skydiver below. As the skydiver falls and he encounters the force of air resistance. An amount of air resistance is dependent up

Distance of the earth from the moon and the sun is, Distance of the earth f...

Distance of the earth from the moon and the sun is? The distance of the earth from the moon is 2,40,000 miles or24 x 104 miles and that from the sun is 93,000,000 or 93x106 mil

At which rate any part of a wave travels, Which of the answers listed below...

Which of the answers listed below best completes the statement: The rate at which any part of a wave travels from one place to another determines the waves: a) Propagati

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

Determine the speed of ball, Tiger Woods can hit a golf ball with 55 N of f...

Tiger Woods can hit a golf ball with 55 N of force. How hard does the ball hit back on the club? (a) more than 55 N of force, (b) less than 55 N of force, (c) exactly 55 N of force

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