Fullerenes with metals inside

Direct detection and quantitation of He@C60 by ultrahigh-resolution Fourier transform ion cyclotron resonance mass spectrometry

“…In a recent finding, it was shown that fullerenes extracted from the Allende and Murchison meteorites contained endohedral helium [24]. The 3 He/ 4 He ratio in those fullerenes was very high, ϳ150 times greater than in the earth's atmosphere and similar to the value estimated for the early solar system. In the above studies, the noble gases were detected and quantified by pyrolyzing the material to release the gas, which was detected in either a quadrupole mass spectrometer [1,3,25] or a linear time-of-flight mass spectrometer [24].…”

“…However, that method is not suitable for analyzing He@C 60 . At the current yields of incorporation, it is not possible to resolve 4 He@C 60 from the 13 C 4 12 C 56 nuclide of C 60 with most mass analyzers. In this communication, we report negative-ion electrospray [26 -28] FT-ICR mass spectrometry [29] of C 60 samples containing 3 He@C 60 and 4 He@C 60 prepared by the labeling method.…”

“…Reduction of ion density within the cell, e.g., by SWIFT isolation and/or evaporative cooling (by lowering the axial electrostatic trapping potential in a series of steps), is necessary to achieve high resolution, because high ion population density results in significant Coulombic interactions between ions with associated coalescence and distortion of cyclotron resonances. Coalescence is especially prevalent when an ion packet of high ion density (e.g., 12 C 60 Ϫ ) orbits at a cyclotron frequency close to that of a low-abundance ion packet of interest (e.g 13 C 4 12 C 56 Ϫ ). High ion population density can also produce a non-quadrupolar variation of the electrostatic field in the ICR trap [34].…”

“…The spectrum was internally calibrated with respect to 12 Figure 1), were baselineresolved (mass resolving power, m/⌬m 50% , ϳ300,000) and the calculated mass difference was 10.9 mDa, in excellent agreement with the theoretical 10.8 mDa value. It was also possible to resolve (see inset, Figure 1) the peaks corresponding to the species, 4 He@ 13 C 12 C 59 Ϫ and 13 C 5 12 C 55 Ϫ (m/⌬m 50% Ϸ200,000). The increased relative abundance of the endofullerence in the latter mass doublet reflects the increased probability that a molecule comprising sixty C atoms contains one rather than five 13 [64,65] were observed here by electrospray, in agreement with the prior findings of Wu et al [49].…”

“…[4]) were observed [5,6] soon after the discovery of buckminsterfullerene (C 60 ) [7]. Following the development of the Krätschmer-Huffman method for preparation of fullerenes [8] (an electrical discharge between graphite electrodes in the presence of 0.2 atm of He gas), Smalley and co-workers produced macroscopic quantities of endohedral metallofullerenes in laser vaporization experiments on graphite doped with metal salts [4]. Weiske et al [9] observed helium within the fragments of C 60 ϩ following high-energy collisions between the cations and the noble gas.…”