title: Functional group-selective adsorption using scanning tunneling microscopy.
abstract: In this study, we selectively enhanced two types of adsorption of 3-mercaptoisobutyric acid on a Ge(100) surface by using the tunneling electrons from an STM and the catalytic effect of an STM tip. 3-Mercaptoisobutyric acid has two functional groups: a carboxylic acid group at one end of the molecule and a thiol group at the other end. It was found that the adsorption occurring through the carboxylic acid group was selectively enhanced by the application of electrons tunneling between an STM tip and the surface. Using this enhancement, it was possible to make thiol group-terminated surfaces at any desired location. In addition, via the use of a tungsten STM tip coated with a tungsten oxide (WO(3)) layer, we selectively catalyzed the adsorption through the thiol group. Using this catalysis, it was possible to generate carboxylic acid group-terminated surfaces at any desired location. This functional group-selective adsorption using STM could be applied in positive lithographic methods to produce semiconductor substrates terminated by desired functional groups.
authors.affiliation: Department of Chemistry, Molecular-Level Interface Research Center, KAIST, Daejeon 305-701, Republic of Korea.
authors.forename: Young Hwan
authors.initials: YH
authors.lastname: Min
authors.forename: Eun Hee
authors.initials: EH
authors.lastname: Park
authors.forename: Do Hwan
authors.initials: DH
authors.lastname: Kim
authors.forename: Sehun
authors.initials: S
authors.lastname: Kim
mesh_terms: D000327:Adsorption; D002384:Catalysis; D005857:Germanium / Q000737:chemistry*; D016252:Microscopy, Scanning Tunneling; D008958:Models, Molecular; D008968:Molecular Conformation; D013438:Sulfhydryl Compounds / Q000737:chemistry*; D013499:Surface Properties
chemical_list: D013438:Sulfhydryl Compounds; D005857:Germanium; C014650:mercaptoisobutyric acid