atomic decay w/
photon emission
absorption of
photon
excited state of atom
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)