Berlin 2014 – wissenschaftliches Programm

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A: Fachverband Atomphysik

A 6: Clusters (with MO)

A 6.1: Vortrag

Montag, 17. März 2014, 10:30–10:45, BEBEL SR144

Infrared spectroscopy of doped silicon clusters — •Nguyen Xuan Truong, Marco Savoca, André Fielicke, and Otto Dopfer — Institut für Optik und Atomare Physik, TU Berlin, Germany

Doped Si clusters are investigated with resonant infrared-ultraviolet two-color ionization (IR-UV2CI) combined with global optimization and DFT calculations. Neutral Si_mX_n clusters are irradiated with tunable IR light from a free electron laser before being ionized with UV photons from an F₂ laser. Resonant absorption of IR photons leads to an enhanced ionization efficiency for the neutral clusters and provides the size-specific IR spectra. Structural assignment of the clusters is achieved by comparing the calculated linear absorption spectra of the most stable isomers with experimental data. For Si_mC_n (with m+n=6), we found the systematic transition from chain like geometries for C₆ to 3D structures for Si₆ [1]. For further first row doped Si₆X (with X = Be, B, C, N, O) clusters, additional properties have been calculated, such as binding and ionization energies, and natural bond orbitals. All X dopant atoms in Si₆X have a negative net charge suggesting that Si atoms act as electron donors within the clusters. Moreover, the overall structures of Si₆X strongly depend on the nature of the dopant atom (size and valency). While for some of the most stable Si₆X clusters one Si atom in the original Si₇ structure is simply substituted (X = Be, B, C), other cases exhibit a completely different geometry (X = N, O).

[1] M. Savoca, A. Lagutschenkov, J. Langer, Dan J. Harding, A. Fielicke, O. Dopfer, J. Chem. Phys. A 117, 1158 (2013).