Atomic Emission Spectroscopy - might need to add to

AES

Analytical technique for element detection

-emission of light by atoms in excited states

-provides qualitative and quantitative info

-widely used in chem, bio, environmental, and material sciences

AES Principle

-Atoms absorb energy and are excited to higher energy levels

-when they return to ground state, photons are emitted

-each element has a characteristic emission spectrum

-intensity of emitted light is proportional to concentration

Li - red

Na - yellow

K - violet

Rubidium - red

Mg - blue

AES Instrumentation

Key Components:

1. Sample introduction - nebulizer, spray chamber (aerosolizes plasma/ serum)

2. Excitation source -flame, plasma, arc/spark - determines name of test type

3. Monochromator - disperses emitted light

4. Detector - PMT, CCD

5. Readout system - computer

Excitation Sources

1. Flame Emission Spectroscopy (FES) - simple, inexpensive, low sensitivity

2. ICP-AES - high sensitivity, multi-element detection

FES

-AES that uses flame

- sample is aspirated into the flame; aerosol converted to atomic vapor; thermally elevated to excited electronic state

-when atoms return to ground state, they emit light characteristic to that element

Photon Emission by Sodium

Bulk solution, heat -> solution in fine droplets -> solid -> gas -> reducing species; Na gas (ground state) + heat-> excited state -> Na+ photon of radiant energy