Zinc porphyrin-driven assembly of gold nanofingers.
Nanofingers of gold covered by porphyrins are prepared by a combination of atomic manipulation and surface self-organization. A submonolayer of zinc(II) 5,10,15,20-tetrakis(4-tert-butylphenyl)-porphyrin (ZnTBPP) axially ligated to a self-assembled monolayer of 4-aminothiophenol (4-ATP) on Au(111) is prepared and studied using a combination of ultrahigh vacuum techniques. Under the electric field produced by the STM tip, the relatively weakly bound Au surface atoms along the discommensuration lines become mobile due to the strong bond to 4-ATP, while the tendency of the porphyrins towards self-assembly result in a collective motion of gold clusters. The clusters diffuse onto the surface following well-defined pathways along the [112] direction and then reach the step edges where they assembled, thus forming nanofingers. First-principles density functional theory calculations demonstrate the reduction of the binding energies between the surface gold clusters and the substrate induced by adsorption of thiols. Scanning tunneling microscopy images show assemblies across three adjacent discommensuration lines of the Au(111)-(22 x square root 3) reconstruction, which collectively diffuse along these lines to form islands nucleated at step edges.
Arima
Valentina
V
National Nanotechnology Laboratory (CNR-INFM), Distretto Tecnologico ISUFI, Università degli studi di Lecce ,via Arnesano, 73100 Lecce, Italy. valentina.arima@unile.it
Blyth
Robert I R
RI
Matino
Francesca
F
Chiodo
Letizia
L
Della Sala
Fabio
F
Thompson
Julie
J
Regier
Tom
T
Del Sole
Roberta
R
Mele
Giuseppe
G
Vasapollo
Giuseppe
G
Cingolani
Roberto
R
Rinaldi
Ross
R
D003460:Crystallization / Q000379:methods*; D006046:Gold / Q000737:chemistry*; D046911:Macromolecular Substances / Q000737:chemistry; D008422:Materials Testing; D008968:Molecular Conformation; D036103:Nanotechnology / Q000379:methods*; D043942:Nanotubes / Q000737:chemistry*; D010316:Particle Size; D011166:Porphyrins / Q000737:chemistry*; D013499:Surface Properties; D015032:Zinc / Q000737:chemistry*
D046911:Macromolecular Substances; D011166:Porphyrins; D006046:Gold; D015032:Zinc