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

Stationary-orbits, According to uncertainity stationary orbits are accepted...

According to uncertainity stationary orbits are accepted or not?please give reason Ans) According to uncertainity stationary orbits are not accepted because according to station

Introduction of physics- physics essentials, Introduction of physics- Physi...

Introduction of physics- Physics Essentials Why do most people believe physics is too hard? Most people get hung up by the feeling that they do not 100% totally understand what

Electricity, help by post offoce box explan rasistance of a wire

help by post offoce box explan rasistance of a wire

Cyclotron, what is cyclotron

what is cyclotron

Not gate, project on not gate

project on not gate

Explain about centrifugal force, Q. Explain about Centrifugal force? Th...

Q. Explain about Centrifugal force? The centrifugal force is F c =mv 2 /r, Where r is the radius of the orbit and m is the mass of the object and v is the velocity. The

Like and unlike parallel forces, #what are practical examples of like and u...

#what are practical examples of like and unlike parallel forces?#

Physics assignment, A 32.53 N light hangs at equilibrium from two cables at...

A 32.53 N light hangs at equilibrium from two cables at angles 78.3 and 60.2 with respect to the ceiling. What is the tension in the first cable?

What is potential gradient, What is Potential Gradient Magnitude of ele...

What is Potential Gradient Magnitude of electric field at a point on an equipotential surface equal's rate of alter of potential, ΔV, with distance Δx, as point moves perpendic

What are coherent sources, Q. What are coherent sources? Two sources a...

Q. What are coherent sources? Two sources are alleged to be coherent if they emit light waves of the same wave length and start with same phase or have a constant phase differ

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