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Trace Element Accelerated Mass Spectrometry |
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Trace element AMS employs an ultra clean Negative Ion Cs Sputter Source to sputter negative ions from a target. The negative secondary ions are extracted and focus. They are then injected into the tandem accelerator. At the terminal, the atomic molecular secondary ions from the sample are stripped of a number of electrons in a gas or foil stripper. The electron stripping causes molecular break-up through a Coulomb explosion into elemental ions, which are accelerated to higher energy and exit the accelerator. If the diatomic or triatomic molecular ion is stripped to a 3+ or greater charge state, almost all molecules break up into elemental constituents. |
| With TEAMS the resulting atomic ions, which are in a number of different charge states with correspondingly different energies, are extracted from the high-energy end of the tandem accelerator. These atomic ions are then magnetically analyzed for momentum/charge (mv/q) and electrostatically analyzed for energy/charge, which together gives mass/charge (m/q) discrimination. To eliminate interferences from the possible break-up fragments that have the same m/q, the energy of the ion is measured in a surface barrier detector or ionization chamber. | 
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Typical sensitivities are on the order of 0.1ppb in depth-profiling mode and 5 ppt in the bulk analysis mode. Theoretical sensitivities of 1ppt are expected under ideal conditions. |
