Elementary structural motifs in a random network of cytosine adsorbed on a gold(111) surface.
Nonsymmetrical organic molecules adsorbed on solid surfaces may assemble into random networks, thereby providing model systems for organic glasses that can be directly observed by scanning tunneling microscopy (STM). We investigated the structure of a disordered cytosine network on a gold(111) surface created by thermal quenching, to temperatures below 150 K, of the two-dimensional fluid present on the surface at room temperature. Comparison of STM images to density functional theory calculations allowed us to identify three elementary structural motifs (zigzag filaments and five- and six-membered rings) that underlie the whole supramolecular random network. The identification of elementary structural motifs may provide a new framework for understanding medium-range order in amorphous and glassy systems.
Otero
Roberto
R
Interdisciplinary Nanoscience Center, Centre for DNA Nanotechnology and Department of Physics and Astronomy, University of Aarhus, 8000 Aarhus C, Denmark.
Lukas
Maya
M
Kelly
Ross E A
RE
Xu
Wei
W
Laegsgaard
Erik
E
Stensgaard
Ivan
I
Kantorovich
Lev N
LN
Besenbacher
Flemming
F