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

Parallel forces, define like and unlike parallel forces with examples

define like and unlike parallel forces with examples

Which force holding the electrons in bohr''s theory of atom, In Bohr's theo...

In Bohr's theory of the atom, what force was responsible for holding the electrons in their orbit? Ans: Coulomb force or the force of attraction among the proton (nucleus) a

Problems regarding open organ pipes and closed organ pipes, a closed organ...

a closed organ pipe resonates with frequency 6hz and an open organ pipe resonates with frequency 12Hz. if the two organ pipes are joined to form a single organ pipe then it will re

Pfund series, Pfund series: The series which define the emission spect...

Pfund series: The series which define the emission spectrum of hydrogen while the electron is jumping to the fifth orbital. All lines are in the infrared portion of the spectr

Help, #question. A child applies a force F? parallel to the x-axis to a 10....

#question. A child applies a force F? parallel to the x-axis to a 10.0-kg sled moving on the frozen surface of a small pond. As the child controls the speed of the sled, the x-comp

What is acceptor circuit, Q. What is acceptor circuit ? Give the uses of it...

Q. What is acceptor circuit ? Give the uses of it. Acceptor circuit The series resonant circuit is frequently called an acceptor circuit. By proffering minimum impedan

Coherently illuminated one slit producing diffraction, Compare and contrast...

Compare and contrast the pattern which is seen with two coherently illuminated narrow slits in Young's experiment with that seen for a coherently illuminated one slit producing dif

Ratio of masses of proton and electron is, Ratio of masses of proton and el...

Ratio of masses of proton and electron is: (1) Infinite (2) 1.8x10 3     (3) 1.8         (4) None of these Ans: (2) 1.8x10 3

Electromagnetic induction, key headings in project file of electromagnetic ...

key headings in project file of electromagnetic induction

What is intensity-wavelength graph, At certain sharply explained wavelength...

At certain sharply explained wavelengths, the power of X-rays is very large as marked K alpha, K beta .... As shown in figure. These X-rays are called as property of X-rays. At oth

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