The Epitaxial Growth of Self-Assembled Ternaphthalene Fibers on Muscovite Mica

• Published in: Crystal growth & design 2014-02, Vol.14 (2), p.442-449
• Main Authors: Simbrunner, Clemens, Schwabegger, Günther, Resel, Roland, Dingemans, Theo, Sitter, Helmut
• Format: Article
• Language: English
• Subjects: Alignment; Cross-disciplinary physics: materials science; rheology; Crystallites; Diffraction; Exact sciences and technology; Fibers; Materials science; Methods of crystal growth; physics of crystal growth; Methods of nanofabrication; Mica; Molecular structure; Morphology; Muscovite; Physics; Self-assembly; Theory and models of crystal growth; physics of crystal growth, crystal morphology and orientation
• ISSN: 1528-7483; 1528-7505
• DOI: 10.1021/cg400912t

The morphology and structure of 2,2′:6′,2″-ternaphthalene (NNN) deposited on muscovite mica(001) substrates was investigated by scanning force microscopy (SFM) and specular X-ray diffraction measurements. Consistently, both methods reveal the coexistence of needle-like structures with a {111} contact plane and {001} orientated island-like crystallites, which are built up by almost upright standing NNN molecules. Both orientations are characterized by a well-defined azimuthal alignment relative to the substrate surface, which is analyzed by X-ray diffraction pole figure (XRD-PF) measurements. Based on XRD-PF and SFM analysis, the azimuthal alignment of {001} orientated crystallites is explained by ledge-directed epitaxy along the fibers’ sidewalls. These fibers are found to orient along two dominant directions, which is verified and explained by a doubling of the energetically preferred molecular adsorption site by mirror symmetry of the substrate surface. The experimental findings are confirmed by force-field simulations and are discussed based on a recently reported growth model.