TANDEM FOURIER-TRANSFORM MASS-SPECTROMETRY STUDIES OF SURFACE-INDUCEDDISSOCIATION OF BENZENE MONOMER AND DIMER IONS ON A SELF-ASSEMBLED FLUORINATED ALKANETHIOLATE MONOLAYER SURFACE

A new instrument configuration based on a Finnigan FTMS-2000 platform has been applied to the study of surface-induced dissociation (SID) in this research. Benzene monomer ions C6H6+ and dimer ions (C6H6)(2)(+) were impacted on a fluorinated self-assembled monolayer surface at co llision energies ranging from 1 to 70 eV. Benzene cations were chosen for this study because the fragmentation characteristics of the molecu lar cation are well known and its SID has been thoroughly investigated . SID spectra obtained by FTMS-SID are very similar to those reported in the literature for the same surface but exhibit much higher mass re solution. A comparison study of collision-induced dissociation (CID) a nd SID of benzene molecular cations was performed utilizing the same I CR cell and ion detection protocol. It is demonstrated that SID provid es both much higher energy deposition and a narrower internal energy d istribution than CID. The present instrument geometry and experimental protocol demonstrate much higher efficiencies than previous SID studi es by FTMS and much higher mass resolution than previous SID studies u sing other types of mass analyzers.