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

Applications of neodymium-yttrium-aluminium-garnet laser, What are the appl...

What are the applications of Neodymium-Yttrium-Aluminium-Garnet Laser? Applications of Neodymium-Yttrium-Aluminium-Garnet Laser: a. Used into materials processing as like we

Distinguish between negative and positive crystal, Distinguish between nega...

Distinguish between negative and positive crystal?

Stop watch, stop watch + least count+ picture of stop watch

stop watch + least count+ picture of stop watch

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

What are sheathed fibers, What are sheathed fibers? The optics, which h...

What are sheathed fibers? The optics, which has an external cladding whether transparent or opaque, affords a mechanical protection to the optics.

Electromagnetic induction, how to prepare a working model on electromagneti...

how to prepare a working model on electromagnetic induction?

Explain radar, Radar: The term radar is used for radio detection and ra...

Radar: The term radar is used for radio detection and ranging. Radar having of three types of devices, a transmitter, a receiver and indicator devices. It has very high frequen

Explain logic gates, The digital circuit that can be examined with the help...

The digital circuit that can be examined with the help of Boolean algebra is known as logic circuit or logic gate. A logic circuit has two or more inputs but only one output. Th

What is the thermal entry length, Sample Problem: Consider laminar flow thr...

Sample Problem: Consider laminar flow through two infinitely wide parallel plates spaced D apart from one another. What is the thermal entry length?

Calculate the sunrise and sunset local horizon points, This problem examine...

This problem examines the seasonal solar radiation budget at three geographical locations: the Equator, 40º North, and 80º North. NOTES: At a given geographical location, N

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