Grant Johnson - Charge Retention by Gold Clusters on Surfaces Prepared Using Soft Landing of Mass Selected Ions

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      Publication Details (including relevant citation   information):


      Volume:   6

        Issue: 1

        Pages: 573-582


    Published: JAN 2012


        Monodisperse gold clusters have been prepared on surfaces in   different charge states through soft landing of mass-selected   ions. Ligand-stabilized gold clusters were prepared in methanol   solution by reduction of chloro(triphenylphosphine)gold(I) with   borane tert-butylamine complex in the presence of   1,3-bis(diphenylphosphino)propane. Electrospray ionization was   used to introduce the clusters into the gas phase, and mass   selection was employed to isolate a single ionic cluster species   (Au11L53+, L = 1,3-bis(diphenylphosphino)propane), which was   delivered to surfaces at well-controlled kinetic energies. Using   in situ time-of-flight secondary ion mass spectrometry   (TOF-SIMS), it is demonstrated that the Au11L53+ cluster retains   its 3+ charge state when soft landed onto the surface of a   1H,1H,2H,2H-perfluorodecanethiol self-assembled monolayer (FSAM)   on gold. In contrast, when deposited onto 16-mercaptohexadecanoic   add (COOH-SAM) and 1-dodecanethiol (HSAM) surfaces on gold, the   clusters exhibit larger relative abundances of the 2+ and 1+   charge states, respectively. The kinetics of charge reduction on   the FSAM and HSAM surfaces are investigated using in situ Fourier   transform ion cyclotron resonance (FT-ICR) SIMS. It is shown that   an extremely slow interfacial (harp reduction occurs on the FSAM   surface while an almost instantaneous neutralization takes place   on the surface of the HSAM. Our results demonstrate that the size   and charge state of small gold clusters on surfaces, both of   which exert a dramatic influence on their chemical and physical   properties, may be tuned through soft landing of mass-selected   Ions onto carefully selected substrates.

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