| dc.description.abstract | In this study,the adsorption of single and mix thiol molecules on Au(111) were investigate by cyclic voltammetry and scanning tunneling microscopy(STM). First,MAA, MPA, and MPS were separately added to a 0.1 M sulfuric acid .Both MPA and MAA molecules are adsorbed in bilayer configurations, indicating the important intermolecular interaction of hydrogen bonds via –COOH groups in these molecules. Lowering potential of Au(111) electrode results in dissolution of these bilayer structures, yielding patches of MAA and MPA monolayer directly bonded to Au(111). Molecular-resolution STM imaging is used to determine the spatial structures of these molecules. Mercaptopropanic sulfonic acid (MPS) is also examined and compared with MAA and MPA. MPS appears to be adsorbed in monolayer on Au(111). The structures seen with MPA and MPS monolayer adsorbed on Au(111) are all different, indicating that the interaction between terminal groups of these thiol molecules plays an important role in their surface organizations.
In the mix system, MAA+MPA and MPA+MPS were adsorbed on Au(111). In the MAA and MPA parts, the same functional groups cause them to be uniformly mixed and adsorbed on Au (111). In the STM image, the two molecules are different. MPA is brighter than MAA. The ratio of surface adsorption molecule MPA:MAA is not proportional to the composition of the solution, which may be related to the speed of molecular adsorption, and the rate of MPA adsorption is faster. In the MPA and MPS parts, two new structures are observed, which are(√13×√21) and( 3×√13), and molecules are uniformly mixed. | en_US |