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

Benefits of fiber-optic sensors for harsh environments, What are benefits o...

What are benefits of fiber-optic sensors for harsh environments? Benefits of fiber-optic sensors for harsh environments are illustrates below: a. Small, contact measurements

Basic electronics, varacter diode

varacter diode

What is equipotential surface, What is Equipotential Surface Equipoten...

What is Equipotential Surface Equipotential Surface - surface of constant potential.  No work is required in moving charges with such a surface. Electric fields are perpend

Jet propulsion is made possible by action and reaction, Jet propulsion is m...

Jet propulsion is made possible by action and reaction Fit a small cardboard stabilizer to the neck of a balloon by means of adhesive tape. Inflate the balloon, and close the m

A simple model of the earth and moon, A simple model of the earth and moon ...

A simple model of the earth and moon The earth can be shown by an orange or other round object stuck on a piece of bamboo or a meat skewer. A piece of bent wire or knitting nee

Rydberg formula, Rydberg formula (Rydberg): A formula which define all...

Rydberg formula (Rydberg): A formula which define all of the characteristics of hydrogen's spectrum, comprising the Lyman, Paschen, Balmer, Pfund series and Brackett,. For

How much kinetic energy has an electron, In a vacuum tube, electrons accele...

In a vacuum tube, electrons accelerate from the cathode element to the plate element, which is maintained at a positive potential with respect to the cathode. If the plate voltage

What is deforming force, If a force applied on a body causes a alteration i...

If a force applied on a body causes a alteration in the normal positions of the molecules of the body, resulting in a alteration in the configuration of the object either in length

How much work is the wind doing on the locomotive, A train locomotive whose...

A train locomotive whose mass is 1 x 106 kilograms is travelling EAST at a speed of 100 kilometers per hour.  A NORTHERLY wind is applying a force of 100 Newtons on the locomo

Determine the gravitational force of attraction, Two steel balls are at a d...

Two steel balls are at a distance S from one another. As the mass of ONE of the balls is doubled, the gravitational force of attraction between them is: a) Quartered b) H

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