User Account

All Pages

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

Two elementary particles which have infinite life units, Name any two eleme...

Name any two elementary particles which have almost infinite life time? Electron and proton have almost infinite life time.

Explain projectile motion, PROJECTILE: "When a body is thrown upward mak...

PROJECTILE: "When a body is thrown upward making a particular angle 'Q' with the horizontal and moves freely under the action of gravity, it is known as a projectile". EXAMP

Digital principles, define definition priniciples?

define definition priniciples?

Determine the self inductance of the coil, What do you mean by transformer ...

What do you mean by transformer ratio? A current of 2A is passed through a coil of 1000 turns to produce a flux of 0.5µwb. Determine the self inductance of the coil.

Periodic motion, why phase is defined only for periodic motion ?

why phase is defined only for periodic motion ?

Law, define varigonon law

define varigonon law

Calculate the photon fluence rate, The photon fluence rate is 10 7 photons...

The photon fluence rate is 10 7 photons mm -2 sec -1 for a beam of γ rays. One fourth of the photons have energies of 100 keV, one half have energies of 80 keV and the remaining

Banking of curves., assignment

assignment

Can multiple illuminators change colors simultaneously, Can multiple illumi...

Can multiple illuminators change colors simultaneously? Yes. Usually the standard disc rotating motors are of the synchronous form, very reliable, and geared to the most suffi

Describe the construction and working of acousting grating, Describe the co...

Describe the construction and working of acousting grating. Construction and Working of Acousting Grating: The liquid is acquired into a glass cell. The Piezo-electric cryst

Write Your Message!

Captcha
Order Assignment

Featured Services

Order Now

Popular Subjects

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!

Submit Assignment

Academics

Major Subjects

Majors

Get In Touch

whatsapp: +91-977-207-8620

Phone: +91-977-207-8620

Email: [email protected]

TERMS & POLICIES

HELP & SUPPORT

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