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

Electric field intensity, If small test charge is taken as positive than w...

If small test charge is taken as positive than why measured value of electric intensity be somewhat less than the actual value of elctric intensity and vica versa

Illustrate the caesium chloride structure, The Caesium Chloride Structure ...

The Caesium Chloride Structure CsCl structure is basically a simple cubic  lattice with 2 atom basis, where one atom is attached to the lattice point and the other at ( a/2 , a

Heat, What is heat

What is heat

Vibrating strings, Two wires on a piano are the same length and are pulled ...

Two wires on a piano are the same length and are pulled by the same tension. wire 1 vibrates at a frequency 1.5 times the frequency of wire 2. Calculate the ratio of their masses (

Explain synchronous condensers, Synchronous Condensers: A synchronous moto...

Synchronous Condensers: A synchronous motor takes a leading current when over-excited and thus behaves as a capacitor. An over-excited synchronous motor running on no load is call

Q, #question 1:successive disintegration in nucluer physics

#question 1:successive disintegration in nucluer physics

Determine the maximum height the pinball rolls, Let's say I have a pinball ...

Let's say I have a pinball (solid sphere) with a given mass and radius, and it is held back at a certain distance from equilibrium on a spring. The spring constant k is given, and

Evaluate the maximum work done, 10 moles of an ideal gas expands reversibly...

10 moles of an ideal gas expands reversibly and isothermally from a volume if 5 lit. to 50 lit. at 25°C. Find the maximum work done? Express the result in Joules.

Electrostatics, the two point charges +10 nano coulomb and -20 nano coulomb...

the two point charges +10 nano coulomb and -20 nano coulomb are seperated by a distance 0.1m. calculate the neutral point along the line joining of two charges

Explain the prisms, Explain the Prisms, Dispersion and Color A ray of whi...

Explain the Prisms, Dispersion and Color A ray of white light that passes through a prism is dispersed into the visible spectrum. Red light is refracted the least, and purple lig

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