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

Find total capacity of each container, Containers in Illustrations C and D ...

Containers in Illustrations C and D are identical Each container is 3.25'w x 3.25'w  x 8.4'l Total capacity of each container 88.725 cubic feet Each container is filled wi

Define wave, A wave is a disturbance which transmits power and momentum fro...

A wave is a disturbance which transmits power and momentum from one place to the other without the transport of matter.

Properties of bulk matter, Why hot air rises up ?

Why hot air rises up ?

#title.motion in 1 d., #questionsolved assignments..

#questionsolved assignments..

Calculate maximum range r, A tank is filled up to a height 2H by a liquid a...

A tank is filled up to a height 2H by a liquid and is placed on a platform of height H from the ground .the distance x from the ground where a small hole is punched to get maximum

Average speed, A boy goes to market with a average speed of 29 km/h.He retu...

A boy goes to market with a average speed of 29 km/h.He returns back half the way he went with a average speed of 40 km/h.Find average speed for whole journey.

Advantages of three phase system over single phase system, Advantages of th...

Advantages of three phase system over single phase system  a) Rotating magnetic field can be set up, by passing three-phase current by stationary coils.   b) Polyphase s

Coil length of motor , Relationship among current, voltage, Torque,speed,co...

Relationship among current, voltage, Torque,speed,coil diameter,coil length of motor and if any of the above changes how other parameters get affected. Ans) The maximum torque h

Complex variables and rlc circuits, The project consists of a word processe...

The project consists of a word processed (typed) report submitted by the project report due date. Late submissions are penalized 10% of the mark per day, including Saturdays and Su

What is utilisation count, What is Utilisation Count? Utilisation Count...

What is Utilisation Count? Utilisation Count shows status of every processor in a particular mode it implies that overhead mode, idle mode and busy mode with respect to progres

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