Secondary ion mass spectrometer for analyzing positive and negative ions

摘要

A secondary ion mass spectrometer analyzes secondary ions by separating and detecting positive and negative secondary ions generated from a sample when the sample is irradiated with a high speed primary beam. The sample is irradiated with a primary beam such as a high speed atom beam and secondary ions are emitted from the sample. The emitted secondary ions are separated and detected by a quadrupole mass spectrometer. Downstream of the quadrupole mass spectrometer, a plurality of metallic rod electrodes are provided parallel to each other, some of which are supplied with a positive voltage and the rest of which are supplied with a negative voltage. An electrostatic shield surrounds the metallic rod electrodes. The secondary ions are separated into positive and negative secondary ions by the electric fields formed by the metallic rod electrodes. The separated secondary ions are respectively converted into currents by corresponding secondary electron multipliers or Faraday cups.