Ultra-thin gold cluster films by Langmuir-Blodgett-techniques.
The extraordinary electronic properties of the full-shell cluster Au55(PPh3)12Cl6 and its ligand modified derivs. make them one of the most attractive building blocks in future nanoelectronics. The reason is the ability to act as a single electron switch or transistor at room temp. As a consequence of this knowledge, further developments to organize these quantum dots in two dimensions are necessary. In this study, the Langmuir-Blodgett (LB) technique has been applied to generate extended two-dimensionally organized arrangements of Au55(PPh3)12Cl6, Au55[(cyclopentyl)7Si8O12(CH2)3 SH]12Cl6 and of Au55(PhSH)xCl6. Film formation was performed by spreading dichloromethane or pentane solns. of the clusters onto the water surface in a LB trough, followed by compression by means of a film balance. From the p-A isotherms exact cluster dimensions could be calcd. from monolayers, except for Au55[(cyclopentyl)7Si8O12(CH2)3 SH]12Cl6, the size of which resulted as too small. The reason is to be seen in the formation cluster double layers. Brewster angle microscopy (BAM) investigations of the thin films on the water surface, at. force microscopy (AFM) and transmission electron microscopy (TEM) studies of transferred films clearly demonstrated formation of densely packed monolayers and of double layers, resp. These extended mono- and double layers are now available for elec. investigations and the construction of layered systems. Those works are in progress.
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