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

Cryogenics, define

define

When a body is said to be in motion, MOTION: A body is said to be in ...

MOTION: A body is said to be in motion if it alters its position with respect to its surroundings.

Inclined plane frictionless motion help, A block initial located 3m up a fr...

A block initial located 3m up a frictionless inclined plane is given an initial velocity of 6m/s up the ramp. The plane is 10m long and titled by 30 degree. a) How long does it tak

Circular motion, A car of mass 800 kg is pulling a trailer of mass 300 kg u...

A car of mass 800 kg is pulling a trailer of mass 300 kg up the slope of angle ? to the horizontal where sine ? = 1/200. Resistance to motion (apart from gravity) is 1.5 N per kg o

Electric motor, sir please tell me about it

sir please tell me about it

Explain pn-junction diode, PN-Junction Diode: Introduction: An ele...

PN-Junction Diode: Introduction: An electronic device which is made by linking together P-type semi-conductor and N-type semiconductor is known as p-n junction diode or a

Polarisation, what is the working of Nicol prism as polarize r and analyzer...

what is the working of Nicol prism as polarize r and analyzer?

Michelson''s interferometer construction and working in detai, Construction...

Construction and working of michelson''s interferometer in detail

D/a converter, what is virtual ground

what is virtual ground

Potential barrier, Potential barrier One either side of the junction, t...

Potential barrier One either side of the junction, the region ‘D' becomes free from mobile charge carriers. That is on n-type side of D, no free electrons exist and on p-type s

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