absorption of
photon
excited
state of atom
atomic decay w/
photon emission
hn = Eupper - Elower
3
radiative processes :
• photon absorption
• spontaneous decay w/ emission of photon
• stimulated emission
2
collisional processes:
• collisional excitation
• collisional de-excitation
D E
= Efinal - Einitial = hn (radiation)
, 1/2 mv2 (collisional)