Remarkable Periodicities in the Mass Spectra of Carbon Aggregates

Mass spectra of carbon \({{\rm{c}}^{\rm{ + }}}_{\rm{n}}{\rm{,}}{{\rm{c}}^{\rm{ - }}}_{\rm{n}}{\rm{,}}{{\rm{c}}^{{\rm{2 + }}}}_{\rm{n}}\) aggregates produced by various techniques show three different n regions. For n ≲ 10, an alternation behaviour appears with aggregates more abundant for a given parity of n. For 10 ≲ n ≲ 30, the mass spectra exhibit a modulo-4 periodicity. For n ≳ 40, an alternation behaviour appears again and some species as \({{\rm{c}}^{\rm{ + }}}_{60}\) are very intense. These results which are related to the stabilities of the aggregates are discussed.