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

Equilibrium, this article is about equilibrium types but it is dealing with...

this article is about equilibrium types but it is dealing with states of equilibrium. location: http://www.expertsmind.com/course-help/?p=forces-and-equilibrium-types-assignment-he

What sources electromagnetic radiation, Question: What sources electrom...

Question: What sources electromagnetic radiation (a.k.a. light a.k.a. electromagnetic waves)? select the one BEST answer. Answer: Note the significant distinction betwe

Write an expression for interest rate parity, Q. Write an expression for in...

Q. Write an expression for interest rate parity under the condition of imperfect asset substitutability. Answer:  R = R* + (E e - E)/E + a where R denotes the risk premium tha

Weight removed from earth and it consequences., With mans lust for the unkn...

With mans lust for the unknown in space exploration, what will happen to our planet by removing so much weight in the form of spacecraft that will never return and can the earth re

For 9th, can i get this job?

can i get this job?

Inkjet printer, definition, Working principal, applications ??

definition, Working principal, applications ??

Define the process - liquid-solid-liquid, Define the Process - Liquid-Solid...

Define the Process - Liquid-Solid-Liquid? A small quantity of water of mass m = 50g in a container at temperature T = 273 K is placed inside a vacuum chamber which is expatria

The number of unpaired electrons in the fe2+ ion is, The number of unpair...

The number of unpaired electrons in the  Fe2 +   ion is: (1) 0          (2) 4         (3) 6   (4)3 Ans: 4

Degenerate and non-degenerate semiconductor, THE SEMICONDUCTOR in which num...

THE SEMICONDUCTOR in which number of electrons or holes is smaller than N c  and N v  density of state in CB or VB are called non-degenerate semiconductor. The general exponential

Physics of radiation therapy, Physics of radiation therapy The probabi...

Physics of radiation therapy The probability  of  your  having cancer during your lifetime is about 1 out of 4 .Currently three major methods are used alone or in combination

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