CH Bond Dissociation Energies of Polycyclic Aromatic Hydrocarbon Molecular Cations: Theoretical Interpretation of the (M-1)+ Peak in the Mass Spectra
✍ Scribed by Fujiwara, Kenji; Harada, Akinori; Aihara, Jun-ichi
- Publisher
- John Wiley and Sons
- Year
- 1996
- Tongue
- English
- Weight
- 487 KB
- Volume
- 31
- Category
- Article
- ISSN
- 1076-5174
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✦ Synopsis
PM3 molecular orbital calculations were carried out to estimate CH bond dissociation energies of 13 polycyclic aromatic hydrocarbon (PAH) molecular cations. The dissociation energy of a CH bond turned out to be almost independent of the size of the molecular cation and the environment in the cation. Therefore, when a high-energy electron impacts a PAH molecule, all hydrogen atoms must be detached with almost equal probability from the resulting molecular cation. It follows that the [ M -1 I + peak in the mass spectra of PAN molecules cannot be assigned to any particular arylium ion. The highest and the next highest occupied n-molecular orbital in some PAH molecular cations are exchanged on dehydrogenation,