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

Atomic structure, Review guide: gases: heat, temperature, volume

Review guide: gases: heat, temperature, volume

Newtons motion, explain newtons motion law

explain newtons motion law

Electrical susceptibility, It is a measure of how easily a dielectric mater...

It is a measure of how easily a dielectric material polarizes in response to an electric field.

Disadvantages of a.c. transmission of power, Disadvantages of A.C. Transmis...

Disadvantages of A.C. Transmission of power 1. An a.c. line needs more copper than a d.c. line. 2. The construction of an a.c. transmission line is more complex than d.c. tr

Simple harmonic motion, what are characteristics of simple harmonic motion

what are characteristics of simple harmonic motion

Find tension in string, Q. The block of mass M descend with acceleration ...

Q. The block of mass M descend with acceleration a and mass of string is m. find tension in string? Ans: The tension in the string will not be same at all points as the string h

Explain what is light, Q. Explain what is light? Light is certainly ele...

Q. Explain what is light? Light is certainly electromagnetic radiation but the expression electromagnetic radiation is by no means an explanation of what light is. Light is a w

ELECTROSTATIC ., two insulated charged copper spheres A and B of identical ...

two insulated charged copper spheres A and B of identical size have charge q and -3q respectably .when they are brought in contact with each other and then separated,what are the n

Transition metal catalyst , Hydrogenation reactions are facilitated by the ...

Hydrogenation reactions are facilitated by the use of a transition metal catalyst such as Ni or Pt. Predict the signs of ΔH, ΔS and ΔG when hydrogen gas is adsorbed onto the surfac

Diffraction of water waves, Diffraction of water waves Let vibrator ...

Diffraction of water waves Let vibrator produce circular wavefronts travelling along (P). Let X, Y be two vertical glass plates immersed in the tank far away from the vib

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