Scanning tunneling microscopy of the formation, transformation, and property of oligothiophene self-organizations on graphite and gold surfaces.
Two alkyl-substituted dual oligothiophenes, quarterthiophene (4T)-trimethylene (tm)-octithiophene (8T) and 4T-tm-4T, were used to fabricate molecular structures on highly oriented pyrolytic graphite and Au(111) surfaces. The resulted structures were investigated by scanning tunneling microscopy. The 4T-tm-8T and 4T-tm-4T molecules self-organize into long-range ordered structures with linear and/or quasi-hexagonal patterns on highly oriented pyrolytic graphite at ambient temperature. Thermal annealing induced a phase transformation from quasi-hexagonal to linear in 4T-tm-8T adlayer. The molecules adsorbed on Au(111) surface in randomly folded and linear conformation. Based on scanning tunneling microscopy results, the structural models for different self-organizations were proposed. Scanning tunneling spectroscopy measurement showed the electronic property of individual molecules in the patterns. These results are significant in understanding the chemistry of molecular structure, including its formation, transformation, and electronic properties. They also help to fabricate oligothiophene assemblies with desired structures for future molecular devices.
Yang
Zhi-Yong
ZY
Beijing National Laboratory for Molecular Sciences, Institute of Chemistry, and Graduate School, The Chinese Academy of Sciences, Beijing 100080, People's Republic of China.
Zhang
Hui-Min
HM
Yan
Cun-Ji
CJ
Li
Shan-Shan
SS
Yan
Hui-Juan
HJ
Song
Wei-Guo
WG
Wan
Li-Jun
LJ
D002621:Chemistry / Q000379:methods; D004563:Electrochemistry; D004566:Electrodes; D006046:Gold / Q000737:chemistry; D006108:Graphite / Q000737:chemistry*; D006859:Hydrogen / Q000737:chemistry; D016252:Microscopy, Scanning Tunneling / Q000379:methods*; D008956:Models, Chemical; D008968:Molecular Conformation; D015394:Molecular Structure; D013499:Surface Properties; D013876:Thiophenes / Q000737:chemistry*
D013876:Thiophenes; D006046:Gold; D006108:Graphite; D006859:Hydrogen