Langmuir films of thiolated gold nanoparticles transferred onto functionalized substrate: 2-D local organization

The aim of this work is to fabricate ordered arrays of thiolated gold nanoparticles grafted through electrically conductive molecular tethers onto gold electrodes. Dodecanethiol-capped gold nanoparticles were synthesized in a two-phase liquid–liquid system. Cluster size selection by the vapor transfer technique was repeatedly performed in order to obtain a narrow nanoparticle core diameter distribution that peaked around 2 nm. Transmission electron microscopy (TEM) imaging of drop cast films prepared onto carbon-coated grids allowed us to assess the performance of each fractionalization process step and the corresponding particle aggregation behavior. A 1,4-benzenedimethanethiol self-assembled film onto hetero-epitaxial gold on mica has been chosen as a grafting substrate for sizeselected gold nanocluster films. Using an air, room temperature scanning tunneling microscopy (STM), the behavior of drop cast and Langmuir nanocluster films onto this substrate was investigated. Better results in terms of adhesion and 2-D aggregation were obtained in the case of Langmuir films. This performance has been further enhanced by application of the multi-step creep method during the Langmuir film making.