Self-assembly Of Alkyl Mercaptan Molecules And Preparation Of Isotropic Au Islands On The Surface

Alkanethiol adsorpt on Au(111)surface can form highly ordered two-dimensional self-assembled molecular films.This monolayer of alkanethiol film has excellent plasma response and stability in the visible spectrum thus has been widely used in plasma/sensing,catalysis and photonic/supermaterials.The systematic study of alkylthiol self-assembled film has been carried out,but there are still some problems need to be solved,such as the relationship between octanethiol molecular self-assembled structures and S-Au chemical bonds under different coverage.Break key reorganization and so on.In order to solve these problems through experiments,we have carried out detailed analysis and research from the following aspects using the ultra-high vacuum variable temperature scanning tunneling microscope(VT-STM)produced by Omicron,.First part of this thesis is working on the structure properties of octanethiol on Au(111)surface under the different coverage and different annealing temperature level.The molecular self-assembly structure of octanethiol on Au(111)surface has a certain dependence on molecular coverage.With the change of annealing temperature,the surface structure of molecules under different coverage of Au(111)surface is also different.This paper explores the relationship between different structures of octanethiol molecules under low coverage,and finds that as the coverage decreases,the octanethiol molecules change from dense phase structure under saturated coverage to low coverage.The strip-like structure also found a grid-like molecular structure with a lower coverage.It is found that the grid-like structure has a period of 8a and is adsorbed on the Au(111)surface in a lying manner.The molecular structure of octanethiol is a novel molecular structure.Therefore,the second part of our thesis is that use the grid-like molecular structure as a template to successfully control the molecular spectrum of octanethiol by precisely controlling the evaporation temperature and beam current of gold atoms.An isotropic triangular gold island was prepared on the surface of the structure.Through the analysis of the growth mechanism of the Golden Island,it is found that this isotropic triangular gold island is formed by the combination of molecular boundary energy and Jindao step energy.The third part of this thesis,we have studied the molecular chain phase of ethanethiol,which was spontaneously broken and recombined on the surface of Au(111),and was studied by scanning tunneling microscopy(STM)combined with density functional theory(DFT)and molecular dynamics(MD).Self-assembly stability of the RS-Au-SR(R=CH2CH3)/Au(111)interface.It was found by STM image analysis that although the adsorption of the ethanethiol molecule on the Au(111)surface as a whole maintains the strip phase structure,the Au-SR bond occurs in the structural unit(RS-Au-SR)which constitutes the strip phase.Constant breakage and recombination.