Comparative electrochemical and theoretical study of diselenides and disulfides monolayers adsorbed on Au(111).

F. COMETTO; E.M. PATRITO; H. ASCOLANI; V. A. MACAGNO

San Carlos de Bariloche, Argentina

Conferencia; 13th International Conference on solid films and surfaces; 2006

Centro Atómico Bariloche, Argentina.

Since the advent of scanning probe microscopy techniques, a large number of investigations have beenconducted to illustrate the structure of n-alkanethiolate self-assembled monolayers (SAMs). However, little experimental investigations have been reported on the structure of similar SAMs with different functional headgroups. The ability to change the anchor group can potentially make self-assembled monolayer technology useful for environments where an organosulfur monolayer would be unsuitable. Molecule-metal interactions and the 2D surface structure are expected to depend on the anchoring group: structural quality of the aromatic selenolates SAMs is much better than that of thiolates, which is presumably related to a better ability of the selenolates to adjust the surface lattice of the substrate to the most favorable 2D arrangement of the selenolate molecules [1]. On the other hand, the study and characterization of the linkage of different anchoring groups, it is of great importance on the molecular electronic devices stability and conduction. Earlier studies [2] on selenolates monolayers suggest that the lower surface mobility it is due to Se-Au provides a better coupling than S-Au analogues. However, in a recent work Sulphur is shown to be a more conductive head-group than Selenium in alkanechalcogenide SAMs on Au(111) according to topographic STM and apparent tunneling barrier height (ATBH) imaging [3]. In the present work we study the comparative and competitive adsorption of Disulfides and Diselenides on Au(111) by experimental and theoretical methods. Firstly, we characterize the CH3Se-SeCH3 and CH3SSCH3 monolayers by electrochemical impedance spectroscopy (EIS) and scanning tunneling microscope (STM) images in order to compare the quality and the nature of the metal-anchor interaction. Results obtained by superficial techniches are also discussed. Simultaneously, we study the adsorption of SeCH3 and SCH3 on the theoretical point of view. Finally, we investigate the competitive adsorption between selenolates and thiolates from different mixed solutions.TIPO DE PRESENTACION: POSTER