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

What is photoelectric effect, Q What is photoelectric effect? Photoelec...

Q What is photoelectric effect? Photoelectric release is the phenomena by which a good number of substances chiefly metals emit electrons under the influence of radiation such

What is angular velocity, The power of change of angular displacement with ...

The power of change of angular displacement with respect to time is known as angular velocity.

Calculate the volumetric substrate utilization rate, Batch fermentation ...

Batch fermentation For aerobic cultivation of yeast the cell mass concentration, X t , and the concentration of the limiting substrate component (glucose), S t , has been deter

LOGIC, : Construct a regular proof to derive the conclusion of the followin...

: Construct a regular proof to derive the conclusion of the following argument: 1. (A & U) ~R 2. ~(~R v ~A) / ~U

Define wave, A wave is a disturbance which transmits power and momentum fro...

A wave is a disturbance which transmits power and momentum from one place to the other without the transport of matter.

Uncontrollable fission chain reactions, what are uncontrollable fission cha...

what are uncontrollable fission chain reactions complete detail

Find the weekly expense on using the iron box, Q. An iron box of 400 W powe...

Q. An iron box of 400 W power is used daily for 30 minutes. If the cost per unit is 75 paise, find the weekly expense on using the iron box. Energy obsessive in 30 minutes

Newtons laws elephant and feather - free fall, Newtons laws Elephant and Fe...

Newtons laws Elephant and Feather - Free Fall Assume that an elephant and a feather are dropped off a extremely tall building from the similar height at the similar time. Assum

Adiabatic reversible expansion of an ideal gas, Derive the mathematical exp...

Derive the mathematical expression PV r = constant for an ideal gas undergoing adiabatic reversible expansion.

Calculate the fiber volume fraction, An engineer is using DSC to determine ...

An engineer is using DSC to determine the fiber volume fraction of a carbon fiber / epoxy prepreg. It is known that the heat of reaction of the pure, fresh epoxy resin (no carbon

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