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

Direct current, A) Explain the flow of direct current? ( describe direct...

A) Explain the flow of direct current? ( describe direct current) b) Explain  the effect of resistance in circuits? (Describe  effect of resistance)

Elastic collision-car-truck collisions, Elastic Collision Collisions am...

Elastic Collision Collisions among objects are governed through laws of momentum and energy. While a collision occurs in an isolated system, the whole momentum of the system of

what is excatly phase? , Phase in sinusoidal functions or in waves has two...

Phase in sinusoidal functions or in waves has two different, but closely related, meanings. One is the initial angle of a sinusoidal function at its origin and is sometimes called

Which atomic model did erwin schrodinger create, Illustrate which atomic mo...

Illustrate which atomic model did Erwin Schrodinger create? Answer:- Schrödinger's wave equation was on the basis of Heisenberg uncertainty principal that the position and

Measuring with a micrometer caliper, Measuring with a Micrometer Caliper ...

Measuring with a Micrometer Caliper A simple animation of using a micrometer to measure the width of a pencil.

Charles law, Charles' law (J.A.C. Charles; c. 1787) At constant pressur...

Charles' law (J.A.C. Charles; c. 1787) At constant pressure the volume of ideal gas is proportional to the thermodynamic temperature of that gas.

Define the tea in thermos, Define the Tea in Thermos? One liter of tea...

Define the Tea in Thermos? One liter of tea at 90° C is poured keen on a vacuum-insulated container (thermos). The surface area of the thermos walls A=600 cm 2 . The volume am

Photoelecric effect, A radiation of 500nm is incident on a metal surface wh...

A radiation of 500nm is incident on a metal surface whose work function is 3ev.why do we not observe the phenomenon of photoelecric effect? Ans) we do not observe the phenomenon

Electromagnetic waves, Electromagnetic waves: Electromagnetic waves wi...

Electromagnetic waves: Electromagnetic waves with different ranges of frequency constitute an electromagnetic spectrum. Electromagnetic waves are transverse in nature. Visible

Working of a simple microscope, What are lens aberrations? Give reasons for...

What are lens aberrations? Give reasons for them. Illustrate the working of a simple microscope and give a mathematical expression for its magnifying power.

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