​​The ​DC Arc Technique

With the DC Arc technique, a small amount of sample (typically 20-500mg) is loaded into a cup shaped graphite electrode. The sample electrode and a counter electrode are inserted into the stand and connected to a DC Arc Source. 

A momentary AC spark between the electrodes ignites a high temperature DC plasma between the electrodes, exciting the sample atoms, and the plasma is maintained by the DC current flowing between the electrodes. 

As the analytical cycle progresses, elemental impurities in the sample are boiled off and excited in the arc. Different elements boil off according to their volatility and emit their characteristic wavelengths of light. The emitted light is detected by the optical spectrometer which sits adjacent to the arc stand. ​