A Scanning Tunneling Microscope Was Used To Study The Behavior Of Halogenated Aromatic Hydrocarbon Small Molecules On Metal Surfaces

In on-surface synthesis,the final product is regulated by the self-assembly of molecules,the formation of polymers during annealing,and the final dehydrogenation cycle.It is very important to study various surface reaction mechanisms and explore the regulation mode of surface reaction for accurate on-surface synthesis.This paper mainly used epitaxial growth(MBE),ultra-high vacuum and low-temperature scanning tunneling microscope(STM),Raman and other research methods to study the modes and mechanisms of regulating molecular behaviors in surface reactions at different stages,as follows:1.Study on self-assembly structure of 4,6-Dichloro-2,5-diphenylpyrimidine(DCDPP)molecule on Au(1 1 1)and Cu(1 1 1).DCDPP molecules have many ordered self-assembling structures on Au(1,1,1)and Cu(1,1,1).The mechanism of the influence of molecular coverage on self-assembled structure was studied through the changes of self-assembled structure under different molecular coverage.2.Study on structure of 4,4'-dibromo-[1,1'-biphenyl]-2,2 –diamine,(DBBPD)on the Au(1 1 1).DBBPD forms a honeycomb-like self-assembly structure on Au(1 1 1).We found that the migration of free radicals on the carbon skeleton occur after the debromination.Two structures can be formed from unmigrated molecules and migrated molecules,and we found that adjusting the annealing temperature can regulate the proportion of the two structures.3.Preparation of graphene nanoribbon arrays and Study of Polarized Raman spectroscopy.Using 10,10'-dibromo-9,9'-bianthracene(DBBA)synthesis of N=7 armchair graphene nanoribbons,and using 6,12-dibromochrysene(DBCh)synthesis graphene nanoribbons.DBCh molecules have chirality on the surface,and two nanoribbons are synthesized by different dehydrogenation cyclization paths during the on-surface synthesis,one is serrated nanoribbons,the other is nanoribbons with five rings.On Au(11 11 12)surfaces,both N=7 armchair graphene nanoribbons and graphene nanoribbons form DBCh grow along Au(1 1 1)steps and form an array.Two kinds of graphene nanoribbon arrays have been characterized by polarized Raman spectroscopy.