Monday, March 25, 2013

What is an Exciton?

  • It is a bound state of an electron & hole which are attracted to each other by the electrostatic coulomb force.

Exciton Energy Levels


  • An Exciton forms when a photon is absorbed by a Semiconductor (Semiconductor is a material that has a small band gap between the VB & CB).
  • Exciton exists in insulators, semiconductors & some liquids.
  • An Exciton pair is defined as an electron & hole that it leaves behind when it is excited up to the CB.
  • An Exciton Bohr Radius is the distance in an electron - hole pair.

Monday, March 18, 2013

Difference between Aerogel & Xerogel


Aerogel
  • Has very amorphous pattern.
  • Clusters were randomly dispersed. 

Aerogel
     

Xerogel
  • Some peaks in pattern were considerably enhanced.
  • Very distorted by intercalation.

Xerogel


Etiquette

1 . Don’t call someone more than twice continuously. If they don’t pick up your call, presume they have something important to atte...