used to measure the concentration by deleting absorption of electromagnetic radiation by atoms rather than molecules

used to measure trace metals

hollow cathode lamp

evacuation gas tight champer, anode, inert gas (helium or argon) cathode

1)voltage is applied and filler gas is ionized, ions attract to the cathode and collide with metal and knock atoms off which causes metal atoms to excite

2)when atoms return to ground state they emit light energy

3)heat of flame is used to break chemical bonds and form free, unexcited atoms

4)sample solution is aspirated into chamber where it mixes with air and fuel and pases though the baffles where large drops are caught and drained

5)light from the bulb passes through the sample of ground state atoms, the atoms absorps the light and gets excited, as it returns to ground state it emits the same light of the light energy absorbed

used to isolate the desired emission line from other emission lines

also protects the photodetector from escessive light coming from the flame