Berlin 2014 – scientific programme

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A: Fachverband Atomphysik

A 6: Clusters (with MO)

A 6.2: Talk

Monday, March 17, 2014, 10:45–11:00, BEBEL SR144

Vibrational Spectra and Structres of Silicon Hydride Cluster Cation — •Martin Andreas Robert George, Marco Savoca, Judith Langer und Otto Dopfer — IOAP TU Berlin, Germany

Silanes and their derivatives and ions are fundamental species in a variety of chemical disciplines. IR spectra of silicon hydride cluster cations Si_xH_y⁺ produced in a supersonic plasma molecular beam expansion of SiH₄, He, and Ar are inferred from photodissociation of cold Si_xH_y⁺-Ar/Ne complexes obtained in a tandem quadrupole mass spectrometer coupled to an electron impact ionization source and an octopole ion trap. In addition, the clusters are characterized in their ground electronic states by quantum chemical calculations to investigate the effects of ionization and Ar/Ne complexation on their geometric, vibrational, and electronic structure. We present initial results for Si₂H₆⁺ [1], Si₂H₇⁺ [2] and Si₃H₈⁺ [3], which have complex potential energy surfaces, with low-energy isomers featuring unusual three-center two-electron (3c-2e) bonding. The IR spectrum of disilanium, Si₂H₇⁺, a fully H-passivated Si₂ core with a Si-H-Si bridge is described by a 3c-2e bond. The excess proton in the Si-H-Si bridge generates three additional fundamentals, which provide the fingerprint of the 3c-2e bond.

[1] M. Savoca, M.A.R George, J. Langer and O. Dopfer, Phys. Chem. Chem. Phys. 15, 2774-2781 (2013) [2] M. Savoca, J. Langer and O. Dopfer, Angewandte Chemie 125, 1376 (2013) [3] M.A.R George, M. Savoca, O. Dopfer, Chem. Eur. J. 19 45 (2013)