Small Carbon Nano-Onions: An Ion Mobility Mass Spectrometric Study

Abstract

Structures and charges of nanocarbon cluster ions, C n z+ (100 ≤ n ≤ 800, z = 1 and 2), have been determined using ion mobility mass spectrometry. For singly charged ions, a compact cluster ion series was observed in addition to monolayer fullerene ions for n = 260−700 continuously. Previous electron microscopic observations indicated that the compact clusters were bilayer fullerenes (nano-onions), in which the inner and outer layers grow from a structure close to [C 30 @C 230 ] + at n = 260. The present study also suggests that several combinations of inner and outer layer fullerenes were produced. The results indicated that the interlayer distance depended on different combinations of inner and outer layers and that the observed lower limit of the interlayer distance agreed well with that of graphite (3.35 Å). The upper limit corresponded to bilayer structures in which the number of atoms of the inner layer was constant at about 30, the smallest fullerene size observed in this study. Series of monolayers and compact bilayers of doubly charged ions with cross sections that coincided with those of monocations were observed in nearly the same size region as monocations.

Structures of Magnesium Oxide Cluster Cations Studied Using Ion Mobility Mass Spectrometry

“…On the other hand, the two series of Mg n O n + and Mg n O n –1 + were mainly observed in the mass spectrum at E inj = 250 eV (Figure c). The one oxygen-rich and one oxygen-poor series were clearly distinguished in this size range up to n = 27 ( m / z ≈ 1080) because the resolving power between Mg n O n +1 + and Mg n +1 O n + , up to 1080/8 ≈ 140, is much smaller than the mass resolution of the apparatus, m /Δ m ≈ 230 . The Mg n O n + and Mg n O n –1 + series were also observed in previous mass spectroscopic studies. − As the injection energy increases, collision-induced dissociation (CID) is likely to occur more efficiently at the entrance of the cell.…”

“…The one oxygen-rich and one oxygen-poor series were clearly distinguished in this size range up to n = 27 (m/z ≈ 1080) because the resolving power between Mg n O n+1 + and Mg n+1 O n + , up to 1080/8 ≈ 140, is much smaller than the mass resolution of the apparatus, m/Δm ≈ 230. 41 + , which contains one more Mg atom than the latter magic number composition, was extremely low in Figure 1c. This feature was also observed in previous mass spectrometric studies.…”

Geometrical Structures of Gas-Phase Cerium Oxide Cluster Cations Studied by Ion Mobility Mass Spectrometry

“…The experimental CCSs of the observed ions were calculated from the measured arrival time by using eqs –. In the present ion mobility measurements, the E / N value is 7.5–9.1 Td (1 Td = 10 –17 V cm 2 ), which is similar to or less than that used in our previous IMMS studies − and is considered to be low enough so that the drifting ions can be regarded as thermalized.…”

Probing the structure of giant fullerenes by high resolution trapped ion mobility spectrometry

“…Apart from C 60 , larger carbon clusters ranging in size up to C 240 formed upon laser vaporization of graphite in a continuous flow of helium have also been investigated by IMS and results interpreted in terms of closed shell fullerene cage structures. 32 Recently Misaizu et al 33 have used IMS to study even larger carbon clusters formed in this way. They showed that apart from single-shelled cages, double-shelled fullerene onion cages begin to be observed starting at roughly C 260…”