FORMATION OF GIANT FULLERENE GAS-PHASE IONS ESS-THAN-OR-EQUAL-TO-2N-LESS-THAN-OR-EQUAL-TO-500) - LASER DESORPTION ELECTRON IONIZATION FOURIER-TRANSFORM ION-CYCLOTRON RESONANCE MASS-SPECTROMETRIC EVIDENCE(), 60)

Laser desorption (followed by electron ionization) Fourier-transform i on cyclotron resonance (LD/EI-FTICR) mass spectra have been obtained f or thin and thick deposits of purified C60 as well as benzene extracts of fullerene-laden arc-welded graphite soot under identical mass spec tral conditions. Thick (but not thin) deposits exhibit 'giant fulleren e'-like carbon cluster-ion distributions, in either positive- or negat ive-ion mode; giant fullerene ions observed by mass spectrometry there fore do not necessarily prove that neutral giant fullerenes were prese nt in the original sample, which is consistent with recent laser vapor ization and plasma desorption mass spectrometry results. FTICR-MS of t he residual soot remaining after benzene extraction yielded much more abundant 'giant fullerene' ions extending above C500+, which are proba bly derived both directly from the corresponding giant neutral carbon clusters in the sample and by the nucleation process seen for thick de posits of the extracts. The results shown here firmly establish the im portance of sample thickness in the mass spectrometric examination of fullerene soot.