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

Diffraction interference, Derivation

Derivation

Explain displacement, Explain displacement x(t) is known as displaceme...

Explain displacement x(t) is known as displacement and it denotes the position of a body at time. If the displacement is positive then that body is to the right of the chosen

Rectifier, junction diode as a half wave rectifier

junction diode as a half wave rectifier

Electricity, Characteristics of resistances connected in parallel

Characteristics of resistances connected in parallel

Kinematics in 2-D, If zoe kicked a soccer ball with an initial velocity of ...

If zoe kicked a soccer ball with an initial velocity of 8.25 m/s at an angle of 15.0 degrees, what horizontal distance would it travel?

Physics Matlab Report, Hello, I have some computing physics coursework in...

Hello, I have some computing physics coursework involving Matlab. I would like to know if your organisation can get this coursework done for me. I am ready to upload the assignme

Polarisation, describe the construction and working of a Nicol prism.discus...

describe the construction and working of a Nicol prism.discuss how you obtain a plane polarised beam with it?

Projectile motion, a projectile is fired horizontally from an inclined plan...

a projectile is fired horizontally from an inclined plane (of inclination 45 with horizontal)with speed=50 m/s.if g=10 m/s2 the range measured along the incline is

Force, explain with the aid of a diagram what is meant by the moment of a f...

explain with the aid of a diagram what is meant by the moment of a force about point

Why does sun seems flat during sunrise and sunset, Q. Why does sun seems fl...

Q. Why does sun seems flat during sunrise and sunset? Answer:- The sun rays have to move through a larger atmospheric distance. The majority of the blue light and shorter

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