Eur. Phys. J. D 17, 37-41 (2001)
https://doi.org/10.1007/s100530170034

Production of large metallocarbohedrene clusters using a pulsed arc cluster ion source

Fachbereich für Physik, Universität Konstanz, 78457 Konstanz, Germany

Corresponding author: ^a gerd.gantefoer@uni-konstanz.de

Received: 20 December 1999
Revised: 18 May 2001
Published online: 15 October 2001

Abstract

The hypothesis of the existence of multi-cage structures of metallocarbohedrene clusters ("metcars" ) bases on the observation of certain magic numbers in the mass spectra corresponding to an excess of carbon atoms with respect to the bulk stochiometry (1:1 for TiC). E.g., the appearance of the magic number cluster Ti₁₃C₂₂ has been explained by assuming a double-cage structure. However, the same magic number can be assigned to a cube (= Ti₁₃C₁₄) with 8 additional carbon atoms forming carbon dimers at the corners of the cube. We recorded mass spectra of Ti_nC_m clusters using a pulsed arc cluster ion source with an additional annealing discharge. For the positive ions, Ti₈C is the major peak in the mass spectrum. For the anions, much larger clusters could be generated. The maxima of the larger Ti_nC clusters including Ti₁₃C are located at masses slightly above the fcc cubic shell closings. The shift can be explained by the bonding of additional C atoms at the corners of the cubes.