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

Electronics, define opto isolators?

define opto isolators?

Determine the maximum bending moment, The weightless simply supported beam ...

The weightless simply supported beam below has a VDL of P61kN/m, a point load of P62 kN and a UDL of P63 kN/m as shown.  Determine the vertical reaction force at A the maximum bend

Rotational motion, how rotational motion was investigate

how rotational motion was investigate

Ergosphere, Ergosphere The region about a rotating black hole, among t...

Ergosphere The region about a rotating black hole, among the event horizon & the static limit, where rotational energy can be extracted through black hole.

Maximum power transfer in dc circuit, Maximum power transfer: Every sou...

Maximum power transfer: Every source of EMF has internal resistance.  If it is required to develop the maximum possible amount of power in an external load, then the load resis

Bread-board, The holes in bread board in horizontal direction have same vol...

The holes in bread board in horizontal direction have same voltage when a potential is given and same is the case with the verticle holes in the middle portion...May I know the rea

Radius of an atom is of the order, The radius of an atom is of the order of...

The radius of an atom is of the order of: (1) 10 -10 cm (2) 10 -13 cm (3) 10 -15 cm (4) 10 -8 cm Ans: (4)10 -8 cm

Rayleigh-jeans law, Rayleigh-Jeans law For any blackbody at thermodyna...

Rayleigh-Jeans law For any blackbody at thermodynamic temperature T, the radiancy R onto a range of frequencies among nu & nu + dnu is provided by R = 2 pi nu 2 k T/c 2 .

Experiment of a uniform motion, Uniform motion When a body falls by a f...

Uniform motion When a body falls by a fluid, the pull of gravity is soon balanced by the frictional forces set up, and it continues to move at a constant velocity. If this is t

Define cathode rays, Cathode rays, discovered by Sir Willium Crooke are the...

Cathode rays, discovered by Sir Willium Crooke are the stream of electrons. They may be given by using a discharge tube containing gas at a low pressure of the order of 10-2 mm of

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