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

Thin films, 2. Surface Crystallography and Epitaxy Fe thin films are grown...

2. Surface Crystallography and Epitaxy Fe thin films are grown on a single-crystal Al (100) substrate surface. The films grow with no dislocations (if they are thin enough) which

Damping coefficient, what is the physical significance of damping coefficie...

what is the physical significance of damping coefficient?

Waves and optics, two travelling sinusoidal waves are described by the wave...

two travelling sinusoidal waves are described by the wave function, y=55

Calculated constraint relation, What is calculated constraint relation?

What is calculated constraint relation?

Kinemetics, An airplane accelerates down a runway at 3.20 m/s2 for 32.8 s u...

An airplane accelerates down a runway at 3.20 m/s2 for 32.8 s until is finally lifts off the ground. Determine the distance traveled before takeoff. I need help of an expert who ca

Derive the wave equation, Starting from Maxwell's e-m equation, get the wav...

Starting from Maxwell's e-m equation, get the wave equation for E in an ionized medium. Identify the dissipative terms in the equation.

Illustrate properties of electromagnetic waves, Q. Illustrate what two prop...

Q. Illustrate what two properties of electromagnetic waves are used to attach info to radio signals? Answer:- By changing the amplitude of a radio wave you can encode info

Electrons, after formation of bond where does electron rotate

after formation of bond where does electron rotate

Experiment on thermo electric thermometers, what are some advantages of th...

what are some advantages of the thermo-electric thermometer over the mercury in glass thermometer?

Draw a free-body diagram for a submerged beach ball, Draw a free-body diagr...

Draw a free-body diagram for a submerged beach ball as it rises toward the surface just after being released. Recognize the forces acting on the beach ball and show the directi

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