Scanning Tunneling Microscopy Study For Self-assembly Of 2,3,5,6-Tetra (2’-pyridyl) Pyrazine On Au(111) Surface

It is very important for our understanding the physical,chemical,biological,and many other processes to study the organic molecular adsorbates systems on metallic surface.And,supramolecular self-assembly is also an important way to construction new artificial structures and functional devices in the bottom-up scheme.In this thesis,we have investigated the Self-assembly of 2,3,5,6-Tetra(2-pyridyl)pyrazine(TPPZ)molecule on Au(111)surface by an ultrahigh vacuum low-temperature scanning tunneling microscope.In Chapter 1,we briefly introduced the fundamental principles and methods of STM and STM system with theoretical method used in this thesis.In the end,we described the system of the ultrahigh vacuum low-temperature scanning tunneling microscope used in this work.In Chapter 2,we reviewed the recent progress in the study of organic molecular adsorbates systems on metallic surface.This chapter is the introduction of our work.In Chapter 3,we have investigated the Self-assembly of 2,3,5,6-Tetra(2-pyridyl)pyrazine(TPPZ)molecule on Au(111)surface by an ultrahigh vacuum low-temperature scanning tunneling microscope.The TPPZ molecules exhibit topography multiplicity in their two-dimensional self-assembled adlayers depending on the coverage of the molecules.The molecules show the preferential adsorption on the step edges at 120 K and at low coverage the molecules gather into chiral trimers with a random distribution on the substrate.When the coverage reaches a threshold value the molecules will form strip superstructures and Honeycomb-like.And the TPPZ molecules will form three-molecule chain close packed structure at one monolayer.After annealing to 380 K the strip structure and three-molecule chain close packed structure will transfer to the honeycomb-like structure,and this structure are stable until annealing to 410 K.