Anomalous stability of B+13 clusters

✍ Scribed by Ryoichi Kawai; John H. Weare

• Publisher: Elsevier Science
• Year: 1992
• Tongue: English
• Weight: 242 KB
• Volume: 191
• Category: Article
• ISSN: 0009-2614
• DOI: 10.1016/0009-2614(92)85306-u

✦ Synopsis

Electronic and geometric isomers of boron 13 clusters have been calculated in the local density approximation. Simulated annealing was used to identify the lowest energy atomic configuration. The filled icosahedral structure is unstable and evolves with continuously decreasing energy to a locally stable structure based on a capped hexagon. While locally stable, heating and slow cooling leads to a considerably more stable structure (0.68 eV) with high symmetry (C3v) and relatively high coordination which is also based on capped hexagons. The remarkable stability of this isomer may explain the measured high survival of Bi% clusters on collision and its relatively low reactivity.

Despite increasing technological interest in boronrich materials [ 1,2 ], little is known about bare boron clusters. A most interesting property of these aggregates is the remarkable change in stability and reactivity with size. Recently a series of experiments on the isolated B~ have been reported by . The mass spectra of clusters from a laser ablation source [3] exhibits anomalously high intensity at N= 13 in comparison with N= 12 and 14. Measurement of collision-induced dissociation [ 3 ] also indicates that high kinetic energy B~+3 is anomalously stable against the collision with rare gas atoms. Even more interestingly, cross sections of reactive collision with deuterium [4 ] and water [ 5 ] show a dramatic decrease at N= 13. These data suggest that B ~-3 is mechanically and chemically more stable than Bi%. The unique properties of the 13 atom boron system deserve special attention. In