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

simulation, what is meaning simulation laser produced plasm

what is meaning simulation laser produced plasma

Top of a tower a stone, From top of a tower a stone is thrown up and it rea...

From top of a tower a stone is thrown up and it reaches the ground in time t1. A second stone is thrown down with the same speed and it reaches the ground in t2. A third stone is r

Can you define solar constant, Q. Can you define Solar Constant? The lu...

Q. Can you define Solar Constant? The luminosity of the Sun L is 3.827×10 26 Watts. When the Sun is straight overhead on a clear day how many watts would we expect to illumina

Show the linked representation of the graph, Q. Show the linked representat...

Q. Show the linked representation of the graph.                                                            Ans: The linked representation of given graph is:

Determine the moment applied to the bolt, The wrench shown in the figure is...

The wrench shown in the figure is designed for access to the bolt at O.  The wrench lies in a vertical plane and a horizontal force of P27 (as in question 14) is applied at A perpe

Determine the length of the ramp, A skateboard track has a horizontal segme...

A skateboard track has a horizontal segment followed by a ramp that declines at a 45° angle, as shown.   Normal 0 false false false EN-IN X-

LASER, What is LASER? describe the construction and working of He-Ne Laser ...

What is LASER? describe the construction and working of He-Ne Laser with suitable diagram

Function of photodetectors in fibre optic communication, Define the functio...

Define the function of photodetectors in fibre optic communication system. Photo-detectors: At the receiver end, conversion of optical signal into analog signal is being don

Microwave, Write an assembly program to make a microwave. Need: 1.    T...

Write an assembly program to make a microwave. Need: 1.    The microwave has a clock (hh:mm:ss am/pm) and the user should be able to alter the clock at any time. 2.    For c

Force, conditions of equilibrium for concurrent force system

conditions of equilibrium for concurrent force system

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