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 instrume nt was designed to do cluster ion reactive scattering, and the availab le cluster sources and the kinematics of these reactions impose some d ifficult design considerations. Many of these considerations also appl y to ion-fullerene scattering, and this was a major application. The i nstrument incorporates a radio-frequency storage/thermalization trap t o control the internal temperature of reactant cluster ions. Cluster i ons are mass-selected by a large gap, large radius magnetic sector tha t can be electrically floated. Reactions are studied in a three sectio n octapole ion guide, equipped with a reaction cell. The reaction cell also serves as an oven to generate target vapor from non-volatile mat erials such as fullerenes. Product mass analysis is done by a large ga p, large radius double focusing mass filter, all of which floats at ac celeration potential. Ions rue detected by an in-line scintillation de tector that can operate at voltages up to 50 kV to allow efficient det ection 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.