Heidelberg 2015 – scientific programme

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MO: Fachverband Molekülphysik

MO 15: Clusters in Molecular Physics (with A & MS)

MO 15.2: Talk

Wednesday, March 25, 2015, 15:00–15:15, PH/SR106

Vibrational spectra and structures of C, B, and N-doped silicon clusters — •Nguyen Xuan Truong, Bertram Jaeger, Philip Jäger, Marco Savoca, Andre Fielicke, and Otto Dopfer — IOAP, TU-Berlin, Germany

Doping Si clusters changes their physical and chemical properties in a way that might be promising for the miniaturization trend towards nanoelectronics. Here, we investigated Si clusters doped with C, B and N with resonant infrared-ultraviolet two-color ionization (IR-UV2CI) and global optimization coupled with electronic structure methods. Doped Si 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-UV2CI spectra. Structural assignment of the clusters is achieved by comparing the experimental IR-UV2CI spectrum with the calculated linear absorption spectra of the most stable isomers. Low-energy isomers are found with the help of genetic and basin-hopping algorithms. For Si_mC_n (with m+n=6), we observed the systematic transition from chain like geometries for C₆ to 3D structures for Si₆. We showed for the first row doped Si₆X (with X = Be, B, C, N, O) clusters that different structures, vibrational and electronic properties can be achieved depending on the nature of the dopant atom. All dopant atoms in Si₆X have a negative net charge suggesting that Si atoms act as electron donors within the clusters. Finally, vibrational spectra and structural assignments for B and N-doped Si clusters are discussed in detail.