Dynamic Observation of Confined Molecules in Self-Assembled Molecular Corrals

Molecular corrals self-assembled on a Si(111)-(7 × 7) surface after pyrrole exposure, enclosing silicon adatom sites where trimethylphosphine (TMP) was then datively adsorbed. The phosphine’s dynamic motion was investigated by scanning tunneling microscopy. The TMP was confined by the corral, hopping on adatom sites within it. Density functional theory calculations showed covalent bonding between the pyrroles and surface silicon atoms because of N–H dissociative adsorption. An electropositive potential around the TMP/Si cluster may induce electrostatic repulsion between the adsorbed molecules.