  The photon-like electronic dispersion of graphene bestows its charge carriers
with unusual confinement properties that depend strongly on the geometry and
strength of the surrounding potential. Here we report bottom-up synthesis of
atomically-precise one-dimensional (1D) arrays of point charges aimed at
exploring supercritical confinement of carriers in graphene for new geometries.
The arrays were synthesized by arranging F4TCNQ molecules into a 1D lattice on
back-gated graphene devices, allowing precise tuning of both the molecular
charge state and the array periodicity. Dilute arrays of ionized F4TCNQ
molecules are seen to behave like isolated subcritical charges but dense arrays
show emergent supercriticality. In contrast to compact supercritical clusters,
extended 1D charge arrays exhibit both supercritical and subcritical
characteristics and belong to a new physical regime termed frustrated
supercritical collapse. Here carriers in the far-field are attracted by a
supercritical charge distribution, but have their fall to the center frustrated
by subcritical potentials in the near-field, similar to the trapping of light
by a dense cluster of stars in general relativity.
