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

The basic capacitor, THE BASIC CAPACITOR If we have two metal plates cl...

THE BASIC CAPACITOR If we have two metal plates close together, but separated by an insulator or dielectric (which could be air) and we apply a voltage across them, electrons a

Electrostatic, Why we are showing work done over a closed path is zero to ...

Why we are showing work done over a closed path is zero to prove that electrostatic forces are conservative

Rotational kinematics.., A wheel is mounted on a stationary axle starts at ...

A wheel is mounted on a stationary axle starts at rest and is given the following angular acceleration a =(9-12t) (SI units)where t is the time after the wheel begins to rotate.Fin

Bronze, Bronze: Copper when alloyed with tin (8% to 16%) and a very small ...

Bronze: Copper when alloyed with tin (8% to 16%) and a very small percentage of a third element like cadmium, beryllium, phosphorous, silicon etc, is called Bronze. Bronzes are gi

Solid state physics, can you do assignments ?

can you do assignments ?

Like and unlike parallel forces, #what are practical examples of like and u...

#what are practical examples of like and unlike parallel forces?#

Explain capacitor, A new 90.0-V battery with a storage capacity of 2.5 x 10...

A new 90.0-V battery with a storage capacity of 2.5 x 10 4 C charges a 6800 μF capacitor with the switch in position A. Then the switch is thrown to position B to discharge th

Gold, Gold:                          Atomic number ...

Gold:                          Atomic number 79 Symbol Au Atomic weight 196.9665 discov

Write the full form of esr, Mention two salient features of immunity theory...

Mention two salient features of immunity theory of ageing. Write the full form of ESR. What does the increase in ESR indicate?

What are the basic components of lead acid cell, What are the basic compone...

What are the basic components of Lead Acid cell? Ans. Basic components of Lead Acid cells are: a) Positive Plates, which are tubular n shape, prepared by PBO 2 b) Negativ

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