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

Tesla, Tesla; T (after N. Tesla, 1870-1943): The derived SI unit of ma...

Tesla; T (after N. Tesla, 1870-1943): The derived SI unit of magnetic flux density, described the magnetic flux density of magnetic flux of 1 Wb by an area of 1 m 2 ; thus it

Michelson interferometer, how Michelson interferometer can be used to measu...

how Michelson interferometer can be used to measure the wavelength of sodium light.

Is it is possible to have charge of 7.2*10^-19 c?, No;(Personal Note:Please...

No;(Personal Note:Please Rate this and let me know if this helps) Reason: From the quantisation of charge charactersistic, we can say that charge comes in integral multiple of e (

Determine the total current flowing, Resistors of 20Ω ,20 Ω and 30Ω  are co...

Resistors of 20Ω ,20 Ω and 30Ω  are connected in parallel. What resistance must be added in serieswith the combination to obtain a total resistance of 10 . If the complete

Spacechargeanddiffusincapacitance, what is space charge and diffusin capaci...

what is space charge and diffusin capacitance.

Define term echo, Echo: The sound heard after reflection from an obstac...

Echo: The sound heard after reflection from an obstacle is known as echo.

Engineering materials and engineering materials properties, Engineers and t...

Engineers and technologist engage themselves in the design and manufacturing of machine like latches, engines, motors, generators, bulldozers etc. And in the fabrication of vehicle

Michelson interferometer, michelson interferometer

michelson interferometer

Radio waves and microwaves, Radio waves and microwaves: What are micro...

Radio waves and microwaves: What are microwaves and radio waves? Ans: Microwaves: 1. The wavelength ranges from 10μm to10m 2. Commonly produced by Electromagnetic osc

Uniform magnetic field, A positively-charged subdivision is moving southwar...

A positively-charged subdivision is moving southward in a downward-directed uniform magnetic field. The magnetic force is the merely force if any acting on the particle. Throughout

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