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

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

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

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

Electrothermal vaporization

Plasma Characteristics Large temperature variation Spectra collected 15-20 mm above coil Free from Ar Ar is chemically inert No oxide formation Little reabsorption

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

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

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

ICP-AES

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

Elements detected by AES

ICP-AES data

Calibration curve