Atoms Producing Radiation

Atoms Producing Radiation

1. Lasers

   • Wavelengths are all the same
   • Light waves are in-step/coherent
   • Light is polarized
   • Stimulated Emission
     • Photon (which precisely matches the energy difference between energy states) stimulates emission of two photons which are identical
     • Photon excites electron to high "pump state"
       • Electron drops down to "long-lived metastable state"
         • Stimulated emission from this state to ground state
   • Popular Inversion
     • Need high number of atoms in high energy states
       • Cavity = enhances particular wavelengths, reinforces constructive and destructive interference

2. Energy level structure

   • Lyman (UV)
     • Ephoton = En - E1
   • Balmer (Visible)
     • Ephoton = En - E2
   • Paschen (IR)
     • Ephoton = En - E3
   • En = -hcR / n^2
     • En = -13.6 eV / n^2