Marie Curie Actions Early Stage Researcher Training Network Interdisciplinary Nanoscience Center (iNANO) Department of Physics and Astronomy University of Aarhus (Denmark) 1st October 2007, Berlin Nataliya Kalashnyk Molecular Networks at Phase Boundaries MONET workshop

“Self-assembly of Molecular Nano-Structures on Dielectric Substrates” Brief Description of my PhD project  Growth of 1D metallic wires on the dielectric films by trapping evaporated metal atoms under the molecules (e.g. Lander molecules) To apply principles of molecular self-assembly in combination with metal deposition to synthesize and investigate nanowires and molecule-electrode nano- contacts relevant for the “molecular electronics” Goal:  Growth of ultrathin dielectric layer by thermal evaporation of NaCl on metallic substrates in UHV  Formation of 1D molecular wires by complementary A-B-A-B- interaction Objectives:

 Herringbone reconstruction is preserved  Ultrathin NaCl(001) film covers step edge of the Au(111) in a “carpet”-like mode  The 1st NaCl layer, named 1 DL, consists of two monoatomic layers of NaCl  On top of 1 DL, the 2 nd (2 ML) and 3 rd (3 ML) monoatomic NaCl layers are formed Au(111)NaCl(001) Growth of NaCl on Au(111) substrate

1st NaCl layer is doublelayer (1DL) 2nd NaCl layer is monolayer (2ML)

Co-adsorption of CA and M on Au(111) 102 x 104 Å 2  Typical ‘rosette motif’: CA:M=1:1, Obtained upon simultaneous deposition.  Hydrogen-bonded, Eb = 0.82 eV/molecule (6 O..H bonds, 3 N..H bonds) Melamine (M) Cyanuric Acid (CA) Rosette structure

Au(111) NaCl CA:M=1:1 on Au(111) E b = 0.82 eV/mol. NaCl (001) on Au (111) CA 1 M 1 structure on NaCl/Au(111) N. Kalashnyk, C. Bombis et al. manuscript in preparation Self-assembly of CA and M on NaCl

Molecular Self-assembly on NaCl/Au(111)

CA structure on NaCl/Au(111) CA 1 M 1 and NaCl islands on Au(111)

Conclusions NaCl growth on metallic substrates:  Growth of large NaCl islands with (100) orientation on Au(111) by thermal evaporation The “1 st layer“ consists of 2 NaCl layers The “2 nd and 3 rd layers” are NaCl monolayer.  Over gold step edges, NaCl presents a carpet like growth mode. Molecular self-assembly on NaCl/Au(111):  CA and M have natural tendency to sit on Au(111) surfaces free of NaCl layers.  However, in several cases, it was clearly observed that CA and M are growing from step edges of NaCl on Au(111).  In some images, we notice that CA and M molecules are stabilized on top of NaCl/Au(111). Stabilization of organic molecules on the insulating layer is achieved by the self-assembly approach.

“Self-assembly of Molecular Nano-Structures on Dielectric Substrates” Brief Description of my PhD project  Growth of 1D metallic wires on the dielectric films by trapping evaporated metal atoms under the molecules (e.g. Lander molecules) To apply principles of molecular self-assembly in combination with metal deposition to synthesize and investigate nanowires and molecule-electrode nano- contacts relevant for the “molecular electronics” Goal:  Growth of ultrathin dielectric layer by thermal evaporation of NaCl on metallic substrates in UHV  Formation of 1D molecular wires by complementary A-B-A-B- interaction Objectives:

On Cu(110) Molecular moulding Molecules from A. Gourdon, CNRS Toulouse Self-assembly of Lander-type molecules M. Yu, W. Xu et al. work in progress

Self-assembly of Lander-type molecules Molecular moulding on Au(111) NaCl (001) on Au (111)