Pure and Doped Silicon Clusters
Ground state structure of Si16V+ with T
symmetry. Several Si-Si and Si-V bonds
are not indicated to emphasize the distortion
from the Td structure, which is predicted as
a low laying transition state. The possibility
for structural interconversion becomes evident
in the fluxional behavior of this cluster.
Silicon is undoubtedly an important material in electronic devices; therefore silicon clusters attract great attention as building blocks for nanomaterials. However, elemental silicon clusters are initially unsuitable as building blocks since they are chemically reactive due to their dangling bonds. This deficiency can be overcome by properly doping the silicon clusters, e.g., with metal atoms or by passivation of the surface. Via choosing a suitable dopant atom one obtains the possibility to steer and fine-tune the chemical, electronic, optical, or magnetic properties of the doped clusters. The changes in the d orbital occupation and excitation energies along the transition metals make them particularly interesting for controlling the cluster properties.
In the previous years we have within a fruitful collaboration with the groups of P. Lievens and M.-T. Nguyen from the University of Leuven (Belgium) focused on the investigation of structural properties of bare as well as doped Si clusters. Approximate structural information, i.e. on the transition from exohedral to endohedral doping, has been gained from adsorption studies. Detailed geometries of small transition metal doped silicon clusters have been determined based on their vibrational fingerprints. Recently we have reported the structures of endohedrally vanadium doped silicon cages and find evidence that Si16V+ is a fluxional system with a symmetric Frank-Kasper geometry.
The investigations of doped and surface modified Si clusters are part of our contribution to the DFG Research Unit 1282: Controlling the Electronic Structure of Semiconductor Nanoparticles by Doping and Hybrid Formation.
Structural Identification of Caged Vanadium Doped Silicon Clusters P. Claes, E. Janssens, V. T. Ngan, P. Gruene, J. T. Lyon, D. J. Harding, A. Fielicke, M. T. Nguyen, and P. Lievens, Phys. Rev. Lett. 107 (2011) 173401.
Disparate Effects of Cu and V on Structures of Exohedral Transition Metal Doped Silicon Clusters: A Combined Far-Infrared Spectroscopic and Computational Study V. T. Ngan, P. Gruene, P.Claes, E. Janssens, A. Fielicke, M. T. Nguyen, and P. Lievens, J. Am. Chem. Soc. 132 (2010) 15589.
Vibrational spectroscopy of neutral silicon clusters via far-IR-VUV two color ionization (Communication) A. Fielicke, J. T. Lyon, M. Haertelt, G. Meijer, P. Claes, J. de Haeck, and P. Lievens, J. Chem. Phys. 131 (2009) 171105.
The Structures of Silicon Cluster Cations in the Gas Phase J. T. Lyon, P. Gruene, A. Fielicke, G. Meijer, E. Janssens, P. Claes, and P. Lievens, J. Am. Chem. Soc. 131 (2009) 1115.
Tuning the Geometric Structure by Doping Silicon Clusters P. Gruene, A. Fielicke, G. Meijer, E. Janssens, V. T. Ngan, M. T. Nguyen, and P. Lievens, ChemPhysChem 9 (2008) 703.
Argon physisorption as structural probe for endohedrally doped silicon clusters E. Janssens, P. Gruene, G. Meijer, L. Wöste, P. Lievens, and A. Fielicke, Phys. Rev. Lett. 99 (2007) 063401.