Small Carbon Clusters (Cn(0), Cn(+), Cn(-)) from Acyclic and Cyclic Precursors. Neutralization-Reionization Mass Spectrometry and Theory
CORNELL UNIV ITHACA NY BAKER LAB
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Ab initio calculations of isomeric carbon clusters C sub n0 and C sub n, n 2-4, yield structures and energies similar to previous reports, although five not two C4 structures have local energy minima. Dissociative ionization of structurally varied precursors was used to prepare C3 and C4 ionic and neutral isomers however, their mass spectra from collisionally activated dissociation CAD and neutralization-reionization NR under a wide variety of conditions are indistinguishable, indicating only one isomer or the same mixture of isomers. Likewise, CAD and NR spectra of C4 and C40 from 13 CH2CHCH13CH2 and C3 and C30 from CH213CHCH3 show complete 13C12 C scrambling. CAD cross sections are consistent with C4 - C6 ions as mainly linear isomers and C7 ions from cyclic precursors as mainly cyclic. Product abundances from the unimolecular dissociation of C sub 0, C sub n-, and C sub n allow the selection of thermodynamic data that should be of higher relative accuracy, such as 11.4 eV for the C3 ionization energy from reported values of 10.0-13.0 eV.
- Polymer Chemistry
- Nuclear Physics and Elementary Particle Physics