Annealing carbon cluster ions. A mechanism for fullerene synthesis

Journal Article · Thu Feb 17 04:00:00 EST 1994 · Journal of Physical Chemistry; (United States)

DOI:https://doi.org/10.1021/j100058a015· OSTI ID:5147308

Hunter, J M; Fye, J L; Roskamp, E J; Jarrold, M F ^[1]

---

1. Northwestern Univ., Evanston, IL (United States)

We describe studies of the annealing and dissociation of even-numbered carbon cluster ions containing 50-70 atoms. The polycyclic polyyne ring isomers for cluster ions in this size regime can be annealed almost entirely into the fullerene geometry, with a small fraction being converted into an isomer which appears to be a large monocyclic ring. Surprisingly, we find that C[sub 60][sup +] behaves essentially the same as other similarly-sized clusters (such as C[sub 58][sup +]). This has important implications for understanding the mechanism of these structural transformations, as well as the overall scheme for fullerene synthesis. The activation energies for conversion of the polycyclic rings to fullerenes are low and relatively independent of cluster size, though the efficiency of forming a fullerene (rather than a large monocyclic ring) increases with cluster size. Based on our experimental results, a detailed mechanism is proposed to account for conversion of the polycyclic polyyne rings into fullerenes. According to this mechanism, a fullerene fragment is prepared by a Bergman enediyne cyclization followed by a radical-induced ring closure and a retro [2 + 2] process. The polyyne chains are then configured to spiral around the fullerene fragment and zip up to form a spheroidal fullerene. We also consider how these processes fit into an overall scheme for fullerene synthesis from small carbon fragments and describe a scheme that is consistent with the experimental results presented here. 36 refs., 14 figs., 1 tab.

• OSTI ID: 5147308
• Journal Information: Journal of Physical Chemistry; (United States), Journal Name: Journal of Physical Chemistry; (United States) Vol. 98:7; ISSN JPCHAX; ISSN 0022-3654
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360601 -- Other Materials-- Preparation & Manufacture
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400201* -- Chemical & Physicochemical Properties
ANNEALING
CARBON
CHARGED PARTICLES
CHEMICAL ACTIVATION
DISSOCIATION
ELEMENTS
FULLERENES
HEAT TREATMENTS
IONS
ISOMERS
NONMETALS
SOLID CLUSTERS
SYNTHESIS