Unusual nucleation and growth
Fabrication of molecular films with a defined functionality requires the full understanding of the underlying physics. However, several molecular systems show an unusual growth behavior, for example, biphenyl dicarboxylic acid deposited on copper substrate simultaneously displays strong interaction with substrate and low interaction with substrate step edges.
A direct visualization of the system at molecular level provided by the complex UHV system of CEITEC Nano allows explaining the observed unusual growth.
Employing scanning tunneling microscopy, Lukáš Kormoš with his colleagues revealed that the strong molecular substrate interaction is even more pronounced at substrate step edges. This results in the formation of a molecular row decorating step edge, which prevents the attachment of the any further molecules there. On a mesoscopic level this is expressed as molecular repulsion from the step edges.
L. Kormoš, P. Procházka, T. Šikola, J. Čechal: Molecular Passivation of Substrate Step Edges as Origin of Unusual Growth Behavior of 4,4′-Biphenyl Dicarboxylic Acid on Cu(001), J. Phys. Chem. C 2018, 122, 2815.