A triple sector, guided-ion-beam mass spectrometer for cluster ion and fullerene scattering

The design and operation of a unique 5-octapole, triple sector, guided ion beam mass spectrometer is described in this article. The instrument was designed to do cluster ion reactive scattering, and the available cluster sources and the kinematics of these reactions impose some difficult design considerations. Many of these considerations also apply to ion-fullerene scattering, and this was a major application. The instrument incorporates a radio-frequency storage/thermalization trap to control the internal temperature of reactant cluster ions. Cluster ions are mass-selected by a large gap, large radius magnetic sector that can be electrically floated. Reactions are studied in a three section octapole ion guide, equipped with a reaction cell. The reaction cell also serves as an oven to generate target vapor from non-volatile materials such as fullerenes. Product mass analysis is done by a large gap, large radius double focusing mass filter, all of which floats at acceleration potential. Ions rue detected by an in-line scintillation detector that can operate at voltages up to 50 kV to allow efficient detection of heavy ions. Sample results are given for reaction of carbon cluster ions with O-2, and for Mo+ scattering from C-60. Published by Elsevier Science B.V.