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

Explain the self inductance of the coil, A silicon iron ring is wound with ...

A silicon iron ring is wound with 800 turns, the ring having a mean diameter of 120mm and a cross-sectional area of 400mm 2 . If when carrying a current of 0.5 A the relative p

What is the universal law of universal gravitation, What is the universal l...

What is the universal law of universal gravitation? Statement that any particle of matter in the universe attracts any other with a force varying directly as the product of the

How many joules of heat are radiated in 10 seconds, The potential differenc...

The potential difference across a 4 ohm resistor is 20 volts.  Suppose that all of the energy dissipated by this resistor is in the form of heat, how many joules of heat are ra

What is the length of the string, The mass of a string is 4.20 x 10 -3 kg,...

The mass of a string is 4.20 x 10 -3 kg, and it is stretched so the tension in it is 135 N. A transverse wave traveling on this string has a frequency of 260 Hz and a wavelength o

What is utilisation count, What is Utilisation Count? Utilisation Count...

What is Utilisation Count? Utilisation Count shows status of every processor in a particular mode it implies that overhead mode, idle mode and busy mode with respect to progres

Force and motion - a light object moves faster, A light object moves faster...

A light object moves faster Mark off a half-metre on a table top with chalk. Separate this equally into centimetres. Secure a long rubber band and two spring clothes pegs. Atta

Polarized light and unpolarized light, Unpolarized light: In ordinary ligh...

Unpolarized light: In ordinary light (light from sun, bulb etc.) the electric field vectors are given in all directions in a light is known as unpolarized light. The oscillation o

Electrostatics, What is quantisation of electric charge?

What is quantisation of electric charge?

Characteristics of capacitors, (1)         CAPACITANCE: The value of c...

(1)         CAPACITANCE: The value of capacitance depends upon the area of conducting plates, thickness of dielectric material and its permittivity. The frequency of operation

Coherence, COHERENCE : 1) Visible light energy is emitted when the exc...

COHERENCE : 1) Visible light energy is emitted when the excited electrons in atoms undergo transitions to the ground state. 2) In ordinary light sources, these transitions

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