Marie Curie ActionsEarly Stage Researcher Training Network

Interdisciplinary Nanoscience Center (iNANO)Department of Physics and AstronomyUniversity of Aarhus (Denmark)

1st October 2007, Berlin

Nataliya Kalashnyk

Molecular Networks at Phase BoundariesMONET 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 2nd (2 ML) and 3rd (3 ML) monoatomic NaCl layers are formed

Au(111) NaCl(001)

Growth of NaCl on Au(111) substrate

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 Å2

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)

Eb= 0.82 eV/mol.

NaCl (001) on Au (111)

0 22 44 66 88 110

-0.8

0.0

0.8

1.6

2.4

Heig

ht / Å

Length / Å

1.78 Å

CA1M1 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)

0 55 110 165 220 275

-1.5

0.0

1.5

3.0

4.5 SL1 SL2

Hei

ght /

Å

Length / Å

3.22 Å

1.3 Å1.44 Å

Molecular Self-assembly on NaCl/Au(111)

0 50 100 150 200 2500.0

1.3

2.6

3.9

5.2

6.5

Hei

ght /

Å

Length / Å

2.37 Å

1.45 Å

Molecular Self-assembly on NaCl/Au(111)

0 60 120 180 240 300-0.5

0.0

0.5

1.0

1.5

2.0

Heig

ht / Å

Length / Å

0.72 Å

CA structure on NaCl/Au(111)CA1M1 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 “1st layer“ consists of 2 NaCl layers The “2nd and 3rd 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)