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

Driving nails with the help of inertia, Driving nails with the help of iner...

Driving nails with the help of inertia Extend a thin board over the edge of a table and support it well by having someone stand on the part in excess of the table. Try to drive

State lenzs law, Q State Lenz's law. Lenz's law declares that the indu...

Q State Lenz's law. Lenz's law declares that the induced current produced in a circuit always flows in such a direction that it opposes the change or cause that produces it.

Explain radio waves, Radio Waves: Radio waves are electromagnetic waves...

Radio Waves: Radio waves are electromagnetic waves with large range of wavelength from a few millimetres to many meters.

Illustrate the polarity of barrier potential, Illustrate the polarity of Ba...

Illustrate the polarity of Barrier potential. The  free  electrons  which  cross  over  the  junction  recombine  with  the holes of p-type and uncover some of the negative ac

Bread board, what is the function and uses of bread board

what is the function and uses of bread board

How do these short-duration high-intensity bursts originate?, There is stro...

There is strong evidence that some short-duration gamma-ray bursts occur in systems with no star formation and where no massive stars are present, such as elliptical galaxies and g

#title.motion in a vertical circle., why the direction of centripetal force...

why the direction of centripetal force isnot marked in diagram

Explain quasi-static isothermal expansion, Explain quasi-static isothermal ...

Explain quasi-static isothermal expansion A method is reversible only if it is quasi-static and non dissipative.   E.g. A quasi-static isothermal expansion of an ideal gas

What is the sum momentum of the combination object, Regard as two cars both...

Regard as two cars both moving eastward along a straight road. Car 1 is in facade of car 2. Car 1 has a mass of 1200 kg as well as a speed of 24 m/s. Car 2 has a mass of 1100 kg as

Working of single –phase induction motor, Working of Single –phase inductio...

Working of Single –phase induction motor Working : Construction of a single -phase motor is same to that of a three -phase induction motor except that the stator is given wit

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