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sp hybridization in free carbon nanoparticles—presence and stability observed by near edge X-ray absorption fine structure spectroscopy

The presence and stability of sp hybridized atoms in free carbon nanoparticles was investigated by NEXAFS spectroscopy.

L. Ravagnan et al.  Chem. Comm. 47 (2011) 2952

The presence of sp hybridization in the solid state carbon has been considered for a long time as very unlikely if not impossible. Althoug free corbons NPs with less than 20 atoms have sp-based structures as most stable configuration, they react exothermically to form sp2 structures when deposited due to the dangling bonds at the extremities of the isolated sp carbon chains (spCCs).
The feasibility of producing the sp-rich solid carbon was demonstrated a few years ago by som of us by depositing at RT and in high vacuum, pure carbon NPs produced by a Pulsed Microplasma Cluster Source (PMCS). In this source carbon atoms aggregate at remarkably lower temperature than in standard fullerene sources.
While the spectroscopic study of free pre-fullerenic NPs is essential for a better understanding of the intermediate steps of carbon NP formation, to date sp chains have been characterized only in the solid state and not as free NPs prior deposition.
Here we present the first gas phase characterization  by NEXAFS of the bonding structure of sp-rich pre-fullerenic NPs produced by a PMCS.

The experiments show that a predominant fraction of carbon atoms is found in linear sp-chains and that conversion into sp2structures proceeds already at low temperature and in the gas phase

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sp hybridization in free carbon nanoparticles - presence and stability observed by near edge X-ray absorption fine structure spectroscopy
Luca Ravagnan, Tommaso Mazza, Gero Bongiorno, Michele Devetta, Matteo Amati, Paolo Milani, Paolo Piseri, Marcello Coreno, Cristina Lenardi, Fabrizio Evangelista, Petra Rudolf
Last Updated on Thursday, 02 February 2017 21:55