Formation of giant fullerene gas‐phase ions (C 2n+, 60 ⩽ 2n ⩽ 500): Laser desorption/electron ionization Fourier‐transform Ion cyclotron resonance mass spectrometric evidence

Laser desorption (followed by electron ionization) Fourier‐transform ion cyclotron resonance (LD/EI‐FTICR) mass spectra have been obtained for thin and thick deposits of purified C₆₀ as well as benzene extracts of fullerene‐laden arc‐welded graphite soot under identical mass spectral conditions. Thick (but not thin) deposits exhibit ‘giant fullerene’‐like carbon cluster‐ion distributions, in either positive‐ or negative‐ion mode; giant fullerene ions observed by mass spectrometry therefore do not necessarily prove that neutral giant fullerenes were present in the original sample, which is consistent with recent laser vaporization and plasma desorption mass spectrometry results. FTICR‐MS of the residual soot remaining after benzene extraction yielded much more abundant ‘giant fullerene’ ions extending above C 500+, which are probably derived both directly from the corresponding giant neutral carbon clusters in the sample and by the nucleation process seen for thick deposits of the extracts. The results shown here firmly establish the importance of sample thickness in the mass spectrometric examination of fullerene soot.