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 15-20 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 • 10 000 K to 5 000 K

8. Spectrometers • Most spectrometer from 170 nm to 800 nm • 3 basic types • Sequential • Simultaneous multichannel • Fourier transform • Sequential • 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