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

Dimensions, find the dimensions of the following i.power ii.velocity iii.fo...

find the dimensions of the following i.power ii.velocity iii.force

Determine weight and density of metal in kg per meter cubed, A block of met...

A block of metal which weighs 60 newtons in air and 40 newtons under water has a density, in kilograms per meter cubed, of: a) 1000 b) 3000 c) 5000 d) 7000

Exam question 1, #questia 17KG cat is shot out of a hole in the side of a c...

#questia 17KG cat is shot out of a hole in the side of a charged plate when the voltage is suddenly turned up to 5000V. The cat has a charge of 2.377^16c. He lands in a 3kg crate o

Third harmonic- standing waves on a string, Third Harmonic- Standing Waves ...

Third Harmonic- Standing Waves on a String There are a variety of patterns that could be generates through vibrations inside slinky, a string, or rope. Each pattern corresponds

Electrical charges, An electron is constrained to the central perpendicular...

An electron is constrained to the central perpendicular axis of a ring of charge of radius 2.2 m and charge 0.015 mC. See Section 22-6. Suppose the electron is released from rest a

Motion in a straight line, is average speed the magnitude of average veloci...

is average speed the magnitude of average velocity?justify your answer with a suitable example?

What is the magnitude of the component, A 105-N suitcase sits on a rubber r...

A 105-N suitcase sits on a rubber ramp at an airport carousel at a 25° angle. The weight vector can be broken into two perpendicular components. a. What is the magnitude of the

Working model, sir, I am in class xii and i have to submit a project:workin...

sir, I am in class xii and i have to submit a project:working model on any topic in physics. so please help me figure this out

Optical microscopy, Determine whether you can examine a microstructure of d...

Determine whether you can examine a microstructure of dimension 10^(-3)mm distinctly with a magnifying lens of focal length 2cm,assuming that your eye has the average visual acuity

Energy transformation for a dart, Energy Transformation for a Dart In t...

Energy Transformation for a Dart In that case of the dart being launched from the spring gun and the just forces doing work upon the dart are internal forces. Initially, the da

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