1. Atomic Emission Spectroscopy
Emission sources
Applications
Samples
AES operates by exciting elements
Rapid relaxation accompanied by emission of UV or visible light
Properties
Low interelement interference
Excitation for wide range of elements under same conditions
High temperatures

2. Sources Plasma source Ar plasma generally used High temperatures
Inductively coupled plasma (ICP)
Direct current plasma (DCP)
Microwave induced plasma (MIP)
ICP and DCP are main sources

3. ICP source ICP torch components Ar gas 5-20 L/min 3 quartz tubes
RF source
0.5-2 kW
27 or 41 MHz
Ionization initiated by Tesla coil
Ions and e- interact with magnetic field
Flow and heating
Quartz cooling by Ar

4. Sample introduction Samples in Ar in torch center
Nebulizers used for liquid samples
Cross flow of Ar
Fine droplets carried by gas into plasma
Ultrasonic method can also be used
Electrothermal vaporization
Ablation

5. Electrothermal vaporization

6. Plasma Characteristics
Large temperature variation
Spectra collected mm above coil
Free from Ar
Ar is chemically inert
No oxide formation
Little reabsorption

7. Direct Current Plasma 3 electrodes 2 graphite anode
Ar flows from anode to cathode
Contact between anode and cathode
K to K

8. Spectrometers Most spectrometer from 170 nm to 800 nm 3 basic types
Sequential
Simultaneous multichannel
Fourier transform
Move from one element line to the next
Different components for UV and visible

9. Spectrometers Multichannel
Simultaneous collection of different wavelengths
Requires more detectors
CCD or PMT

10. ICP-AES

11. Samples Dissolved samples
Introduction and retention of samples can cause errors
Wide variety of elements
Most elements have several emission lines
Calibration normally linear
Self-absorption can limit linearity

12. Elements detected by AES

13. ICP-AES data

14. Calibration curve