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

Determine the superposition principle, Determine the Superposition Principl...

Determine the Superposition Principle The Superposition Principle for numerous electric potentials, unlike electric fields and forces, is summed algebraically.  Electric potent

Galvanometer, write principles,construction & working of a moving coil galv...

write principles,construction & working of a moving coil galvanometer

Interfacial polarization, Interfacial polarization takes place whenever the...

Interfacial polarization takes place whenever there is an storage of charge at an interface between two materials or between two regions in a material. As shown in the material ha

Electromagnetic induction, what is construction,,, principle...and working ...

what is construction,,, principle...and working of AC generator

Basic concepts of electromagnetic spectrum, Basic concepts of electromagnet...

Basic concepts of electromagnetic spectrum: BASIC CONCEPTS 1. When Sun light falls on a prism, the transmitted light produces a sequence of colours called 'Spectrum'. 2

Compute the quantity of sugar contained in the solution, Q A 300 mm long tu...

Q A 300 mm long tube containing 60 cc of sugar solution produces a rotation of 90 when placed in a polarimeter If the specific rotation is 600, Compute the quantity of sugar contai

Explain simple harmonic motion, Explain Simple Harmonic Motion Many rep...

Explain Simple Harmonic Motion Many repeating motion problems can be solved by taking the displacement as   where d is distance in meters, A is amplitude in meters,

Quantum physics, find the kinetic energy of a proton whose debroglie is 1fm...

find the kinetic energy of a proton whose debroglie is 1fm

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