posted on 2022-09-23, 23:43authored byPhilipp D’Astolfo, Xing Wang, Xunshan Liu, Marcin Kisiel, Carl Drechsel, Alexis Baratoff, Ulrich Aschauer, Silvio Decurtins, Shi-Xia Liu, Rémy Pawlak, Ernst Meyer
Crystalline nanoporous
molecular networks are assembled
on the
Ag(111) surface, where the pores confine electrons originating from
the surface state of the metal. Depending on the pore sizes and their
coupling, an antibonding level is shifted upward by 0.1–0.3
eV as measured by scanning tunneling microscopy. On molecular sites,
a downshifted bonding state is observed, which is occupied under equilibrium
conditions. Low-temperature force spectroscopy reveals energy dissipation
peaks and jumps of frequency shifts at bias voltages, which are related
to the confined states. The dissipation maps show delocalization on
the supramolecular assembly and a weak distance dependence of the
dissipation peaks. These observations indicate that two-dimensional
arrays of coupled quantum dots are formed, which are quantitatively
characterized by their quantum capacitances and resonant tunneling
rates. Our work provides a method for studying the capacitive and
dissipative response of quantum materials with nanomechanical oscillators.