Electron ionization mass spectrometry of synthetic C₆₀

Abstract

Novel carbon clusters isolated in the solid phase have been characterized by electron ionization (EI) mass spectrometry. The crystalline material contains the Cso and C70 molecules in a ratio of 37:l. Both of these molecules form singly charged ions that appear at mlz 720 and 840, respectively, and doubly charged ions that appear at mlz 360 and 420, respectively. Only the Cm molecule produces the triply charged species, at rnlz 240. Cso undergoes fragmentation by losing successive multiples of C2 through CI6. The C,o molecule only loses the fragments Ci and C4. Collisionally activated decomposition of these molecules in the first field-free region did not reveal any more extensive fragmentation than was observed under EI conditions.The existence of an exceptionally stable carbon cluster containing 60 carbon atoms was first reported in 1985 by Smalley and coworkers' thereby marking the beginning of the study of a new form of carbon. In order to account for the unique stability of the C, molecule, a spherical, highly symmetrical, truncated icosahedral structure was proposed. The C, structure was assigned 60 vertices and 32 faces, 12 of which are pentagons and 20 of which are hexagons, thus following the model of a geodesic dome; this similarity led to the name 'buckminsterfullerene', in honor of the architect who first designed this structure, and hence, related members of this new class of carbon compounds are called 'fullerenes'.'Theoretical studies on structure of C, and the fullerenes in general have made predictions of the 'magic numbers' for these cluster^^.^ and discussed their poten-'tial involvement in soot f~rmation.',~ Interestingly, all of the experimental work on these clusters has been done in situ in the mass spectrometer after pulsed-laser vaporization of graphite and subsequent formation of supersonic carbon-cluster beams7 It seems reasonable that many interesting experiments could be performed, including analysis by classical electron ionization (El) mass spectrometry, if purified CW and the other fullerenes were avaiIable in the solid form.The recent publication of a synthetic method for the preparation and isolation of C, in purified form makes available quantities of material needed for a determination of the physical and chemical properties of 'buckminsterfullerene'.* The infrared and ultraviolet absorption spectra of the synthetic C , molecule provide evidence for the presence of a spherical, aromatic structure for the C , cluster.' This sample has also been examined for the first time using EI mass spectrometry and the results of this analysis are presented herein. EXPERIMENTALA model 90 double-focusing mass spectrometer (Finnigan MAT, Bremen, Germany) with a BE configuration was used in all of the experiments. The sample, prepared as described elsewhere,* was introduced into the Author to whom correspondence should be addressed. mass spectrometer using the direct-insertion probe with a heating rate of 2"C/s from ambient temperature to 300°C. The El mass spectrometry conditons were as follow...

Characterization and Liquid Chromatography-MS/MS Based Quantification of Hydroxylated Fullerenes

“…In addition, a peak series from m/z 720 to 576 with a spacing of 24 m/z was found. This has also been observed in earlier studies of fullerenes and has been attributed to sequential C 2 losses 42, 43, 23…”

Formation and fragmentation of C+ n clusters produced from a C60/C70 mixture in an electron-impact ion source

“…The spectrum shown in Fig. 2 and the relative intensities of these fullerene ions are very similar to that observed in the 70 eV electron-impact fragmentation and ionization experiment by Luffer et al [12]. In both cases C~-o fragments by successive loss of C2 through C16.…”

Fullerenes

“…C , для столкнови-тельного разрушения которых требуется энергия больше или порядка 1 кэВ [12, 59,62,68 ].…”