| definition |
In this technique, the target element is first chemically separated from the sample
before it is placed in a sample holder in the AMS instrument. The sample element is
then bombarded by cesium ions to sputter the analyte element from the sample as negative
ions. The analyte ions are then accelerated down a beam tube by a positive potential
difference of several million volts, passed through an electron stripper to convert
them to positive ions, and accelerated back down the beam tube toward common potential
where ion velocities approach a few percent of the speed of light. Using a series
of magnetic and electrostatic mass filters, the ion beam containing all isotopes of
the analyte element is then separated into separate beams containing the (usually
unstable) isotope of interest and other isotopes, and each of the isotopes is counted
by a separate detector. (Skoog, Holler & Crouch, p. 271). Components: 1) sample preparation:
chemical concentration of analyte; 2) ionization: ion beam; 3) mass analyzer: accelerator
Mass spectrometer; 4) detector: not specified.
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