M. Hershfinkel et al., NESTED POLYHEDRA OF MX(2) (M=W, MO X=S, SE) PROBED BY HIGH-RESOLUTIONELECTRON-MICROSCOPY AND SCANNING-TUNNELING-MICROSCOPY, Journal of the American Chemical Society, 116(5), 1994, pp. 1914-1917
Extensive investigation of the newly discovered fullerene-like nested
polyhedra (NP) and nanotubules of metal dichalcogenides by scanning tu
nneling microscopy (STM) and high-resolution transmission electron mic
roscopy is reported. Long-term spontaneous (room temperature) and elec
tron beam assisted crystallization of amorphous precursor into NP or M
X(2) (M = W, Mo; X = S, Se) was observed. This, along with other findi
ngs, suggests that the NP constitute a new metastable phase between th
e starting amorphous material and the thermodynamically stable bulk 2H
allotrope. Characterization of the apex angles by STM suggests that t
he apexes of the NP may contain geometrical elements such as triangles
and rhombuses, which do not exist in nested carbon fullerenes. The en
ergy bandgap of the NP, determined using STM, was found to be somewhat
smaller than that of the bulk 2H phase, and possible explanations for
that phenomenon are forwarded.