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

Spectrum and light, impure and pure spectrum

impure and pure spectrum

Geometrized units, Geometrized units: A system of units in which certa...

Geometrized units: A system of units in which certain fundamental constants (G, c, k, and h) are set to unity. It makes calculations in certain theories, such like general rel

Acceleration, when an object is dropped, what is its acceleration at the mo...

when an object is dropped, what is its acceleration at the moment of release? Explain with reasoning.

Schottky diode, what are the v-i characteristics of schottky diode?

what are the v-i characteristics of schottky diode?

Explain electricity and static electricity, Explain Electricity and static ...

Explain Electricity and static electricity Electricity - study of stationary (static) or moving charges Static Electricitiy (Electrostatics) - electric charges at rest

Explain magnetic dipole moment., Consider a current loop where the circulat...

Consider a current loop where the circulating current is I. This may be for an example of a coil carrying a current. We will assume that the current loop lies within a single plane

State the demerits of ultrasonic magnetostriction method, Illustrate the de...

Illustrate the demerits of ultrasonic magnetostriction method. Limitations of ultrasonic magnetostriction method: a. This can produce frequencies up to 3 MHz simply. b.

Defects of vision, Defects of Vision Long Sightened When a person ...

Defects of Vision Long Sightened When a person can see far objects clearly but cannot see near object clearly then this defect of vision is called as long sightedness.

Are fibers safe, Are fibers safe? Fiber optics are passive components, ...

Are fibers safe? Fiber optics are passive components, hence do not use power to generate light, like the case with lamps. When light conductors only carry light from one point

Variable resistor, The variable resistor is a resistor whose value can be a...

The variable resistor is a resistor whose value can be accustomed by turn a shaft or sliding a control. They are also referred to as potentiometers or rheostats and permit the resi

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