Heterodimerization via the covalent bonding of Ta@Si16 nanoclusters and C60 molecules

Masato Nakaya, Takeshi Iwasa, Hironori Tsunoyama, Toyoaki Eguchi, Atsushi Nakajima

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Abstract

Initial products prepared via the surface immobilization of Ta-atom-encapsulated Si16 cage (Ta@Si16) nanoclusters on solid surfaces terminated with monolayer films of C60 molecules were investigated using scanning tunneling microscopy (STM). The STM results indicated that marked aggregation and desorption of surface-immobilized Ta@Si16 nanoclusters were not induced, even after thermal annealing at -500 K, whereas the local vertical and lateral positions of the Ta@Si16 nanoclusters with respect to neighboring adsorption sites in the C60 film were modified. This local positional transition occurred on C60 monolayer films weakly bonded (via van der Waals forces) to substrates such as highly oriented pyrolytic graphite (HOPG) but did not occur on C60 monolayer films covalently bonded to substrates such as Si(111)7 × 7. These results indicated that the heterodimer consisting of a Ta@Si16 nanocluster and a C60 molecule, Ta@Si16-C60, was formed as an initial product via covalent bonding, which inhibited wide-range surface migration of the Ta@Si16 nanoclusters but allowed them to locally change their positions via thermally activated precessional motion. In addition, the transition temperature of the local positional shift was found to decrease as the area density of the surface-immobilized Ta@Si16 nanoclusters increased, indicating that the barrier height of the precessional motion of the Ta@Si16-C60 heterodimer was decreased due to accumulation of the elastic strain energy generated in the C60 films.

Original languageEnglish
Pages (from-to)10962-10968
Number of pages7
JournalJournal of Physical Chemistry C
Volume119
Issue number20
DOIs
Publication statusPublished - 2015 May 21

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ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Energy(all)
  • Physical and Theoretical Chemistry
  • Surfaces, Coatings and Films

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