High performance SIMS system

The performance of a high‐sensitivity secondary ion mass spectrometer is described. The spectrometer is used for studies of gas–surface interactions and operates under ultrahigh vacuum conditions with a mass‐analyzed primary beam of low energy. The secondary ion detection system incorporates a retardation/acceleration energy analyzer with a large acceptance angle and a central stop which improves the signal/noise ratio. The analyzer emittance was designed to match the acceptance of a quadrupole mass filter. A calibration procedure is used to correct for the velocity discrimination of the quadrupole mass analyzer. Some applications to SIMS and to electron‐induced desorption are illustrated.