Regensburg 2004 – wissenschaftliches Programm

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SYOH: Organic and Hybrid Systems for Future Electronics

SYOH 5: Poster

SYOH 5.17: Poster

Donnerstag, 11. März 2004, 18:00–21:00, B

Substrate and temperature dependent lateral order in N,N’-dibutyl-substituted quinacridone monolayer studied by MBD-LEED — •Feng Lin, Dingyong Zhong, Lifeng Chi, and Harald Fuchs — Physikalisches Institut, Universität Münster, D-48149 Münster, Germany

Ordered monolayers of N,N’-dibutyl-substituted quinacridone (QA4C) were prepared by vacuum sublimation on Cu(110),Ag(110), and Ag(111) surfaces. Using Low energy electron diffraction that was designed specially to follow the growth processes and thus obtain the kinetics of growth phenomena, the nucleation, grwoth, and superstructures of QA4C monolayers were investigated and compared. The strong interlayer interaction between the QA4C molecules and Cu(110) surface results in very low surface diffusivity at room temperature. Consequently, the commensurate monolayer structure of QA4C was only obtained when annealing the substrate up to 420 K and its crstallographic parameters were determined by the substrate lattice rather than the bulk structure of QA4C itself. While for Ag(110) surface, the QA4C monolayer tended to arrange the molecules in accordance with its bulk crystallography. The microscopic mechanism might be the intralayer interaction of H-bond between molecules which becomes significant since the interlayer interaction is weaker than the case of Cu(110). Temperature induced structural transition was observed on Ag(111), where the six symmetry-equivalent domains at room temperature was changed to a single domain that was more similar to its bulk crystallography at about 200 K.