Structure and growth of 4-methyl-4′-mercaptobiphenyl monolayers on Au(111): a surface diffraction study

T. Y.B. Leung, P. Schwartz, G. Scoles, F. Schreiber, A. Ulman

Research output: Contribution to journalArticlepeer-review

130 Scopus citations

Abstract

In an attempt to quantify the role played by the rigidity of the molecular backbone on the self-assembly process, monolayers of 4-methyl-4′-mercaptobiphenyl assembled on Au(111) were characterized by grazing incidence X-ray diffraction and low-energy atomic beam diffraction. Two phases of different density were observed. In the low-density 'striped' phase, the diffraction pattern is consistent with a commensurate rectangular (8 × 2√3) surface lattice. Systematic absences and the intensity modulation in the diffraction pattern suggest that the structure can be composed by staggered molecular rows arranged in a head-to-head orientation with their molecular axes close to the surface. The diffraction pattern of the high-density phase can be described by a commensurate (√3 × √3)R30° surface lattice. The measured intensity variation along the (1,1) Bragg rod is consistent with a tilt angle of at most 19° from the surface normal. Therefore, both similarities and differences with the diffraction patterns of the low-density phase and the high-density phase of the monolayers of n-alkanethiol on Au(111) have been detected. The thermal behavior of the monolayers of 4-methyl-4′-mercaptobiphenyl was also examined. Both phases are found to be thermally more stable than the corresponding phases of monolayers of n-alkanethiols. Finally, the growth behavior of the monolayers of 4-methyl-4′-mercaptobiphenyl was investigated and various growth protocols were tried. Compared with the case of n-alkanethiol monolayers, the high-density phase of the monolayers of 4-methyl-4′-mercaptobiphenyl is more difficult to prepare.

Original languageEnglish
Pages (from-to)34-52
Number of pages19
JournalSurface Science
Volume458
Issue number1
DOIs
StatePublished - 20 Jun 2000
Externally publishedYes

Bibliographical note

Funding Information:
The authors thank Dr A. Eberhardt and Dr P. Fenter for their help and advice in the GIXD measurements, and Professor A. Kahn and Dr G. Poirier for the STM measurements. F. Schreiber acknowledges the financial support from the DFG. A. Ulman thanks the NSF for support through the MRSEC for Polymers at Engineered Interfaces. The GIXD studies were supported by the Department of Energy under Grant No. DE-FG02-93ER45503. The GIXD measurements were carried out at the National Synchrotron Light Source, which is supported by Department of Energy Contract No. DE-AC0276CH-00016.

Funding

The authors thank Dr A. Eberhardt and Dr P. Fenter for their help and advice in the GIXD measurements, and Professor A. Kahn and Dr G. Poirier for the STM measurements. F. Schreiber acknowledges the financial support from the DFG. A. Ulman thanks the NSF for support through the MRSEC for Polymers at Engineered Interfaces. The GIXD studies were supported by the Department of Energy under Grant No. DE-FG02-93ER45503. The GIXD measurements were carried out at the National Synchrotron Light Source, which is supported by Department of Energy Contract No. DE-AC0276CH-00016.

FundersFunder number
National Science Foundation
U.S. Department of EnergyDE-FG02-93ER45503, DE-AC0276CH-00016
Materials Research Science and Engineering Center, Harvard University
Deutsche Forschungsgemeinschaft

    Fingerprint

    Dive into the research topics of 'Structure and growth of 4-methyl-4′-mercaptobiphenyl monolayers on Au(111): a surface diffraction study'. Together they form a unique fingerprint.

    Cite this