2004 Volume 2 Pages 89-92
We have investigated monolayer and multilayer islands of La2@C80, La@C82 and La2@C72 grown on a hydrogen-terminated Si(100)-2×1 surface by ultra-high-vacuum scanning tunneling microscopy/spectroscopy. The observed La2@C80 molecule has a spherical shape, consistent with a recent result by synchrotron X-ray measurements. The La2@C72 molecules are observed by STM as ellipsoids, consistent with a recent report by the 13C-NMR structural analysis. The energy gap for the La2@C80 multilayer islands is measured to be 1.3-1.5 eV, whereas that for La@C82 is 0.5 eV, indicating that the Ih cage of the La2@C80 molecule is highly stabilized by an electron transfer from the encaged La atoms. The energy gap of the La2@C72 multi-layer islands is measured by STS as 1.0-1.2 eV, suggesting that the C72 carbon cage is stabilized by a localized electron transfer from the encaged La atoms to the fused-pentagon area of the fullerene cage. [DOI: 10.1380/ejssnt.2004.89]
