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Au(111) 표면위에 흡착된 싸이클로헥산싸이올 분자의 치환에 의한 방향족싸이올 단분자막의 구조제어

Title
Au(111) 표면위에 흡착된 싸이클로헥산싸이올 분자의 치환에 의한 방향족싸이올 단분자막의 구조제어
Other Titles
Structural Control of Aromatic Thiol Self-Assmebled Monolayers Guided by Displacement of Cyclohexanethiols on Au(111) Surface
Author
성태현
Alternative Author(s)
Sung Taehyun
Advisor(s)
노재근
Issue Date
2015-02
Publisher
한양대학교
Degree
Master
Abstract
Self-assembled monolayers (SAMs) of organic thiols containing aromatic ring on Au(111) were characterized by means of scanning tunneling microscopy (STM), contact angle (CA), and cyclic voltammetry (CV). Simple aromatic thiol SAMs have usually disordered phases. Therefore, we used displacement method to control the structural order of such aromatic thiol SAMs, and CHT SAMs were used as transient layers because of a weak lateral interaction and a lower adsorption density. In this study, to obtain 2D ordered aromatic thiol SAMs, we used 4-fluorobenzenethiol (FBT), 4-methylbenzenethiol (MBT) and 4-hydroxybenzenethiol (HBT) because it has representative withdrawing group and donating group. It is found that CHT SAMs displaced by FBT, MBT and HBT molecules. It is obtained that partially ordered CHT and 4-FBT SAMs were formed after 1h displacement, which are described as (5 × 2√10)R48° zig-zag structure and (4√6 × √3)R5° row structure, whereas the fully covered 4-FBT SAMs were formed after 2h displacement, which is described as (2√21 × √3)R8° row structure. MBT SAMs had two kinds of surface structure by displacement time. Shorter than 20 minutes, we can only find long-range ordered MBT SAMs which can be described (2 √3 × √3)R10° and longer than 1 hour, we can find short-range ordered MBT SAMs which can be described (3 √6 × √5)R10°. In addition, it was found that short-range ordered MBT SAMs had larger contact angle results. HBT solution made disordered phases even if change the solvent but we obtain HBT SAMs through displacement method and it was strongly influenced by solvent. Increasing FBT molar ratio or coadsorption time, ordered phases became disordered phases due to FBT molecules that influenced to make disordered phases. Coadsorption of CHT and FBT molecules with a mole fraction of 1:1 created the formation of phase separated domains with FBT and CHT SAMs. Increasing immersion time or FBT mole fraction, contact angle values increased due to domainant phase of FBT molecules. From our study, we clearly revealed that the controlling surface structure could be a powerful technique for the fabrication of high-quality organic SAMs on gold surface. We can believe that our results will provide meaningful information for understanding surface structure, electrochemical behavior, adsorption condition of aromatic thiol SAMs.
URI
https://repository.hanyang.ac.kr/handle/20.500.11754/129272http://hanyang.dcollection.net/common/orgView/200000425681
Appears in Collections:
GRADUATE SCHOOL[S](대학원) > CONVERGENCE NANOSCIENCE(나노융합과학과) > Theses (Master)
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