Bridging the quasi-atomic state and the state of condensed matter

Surface-supported clusters comprised of only a few atoms provide an ideal model case to explore how solid-state properties evolve with size. Low-temperature STM-based manipulation and spectroscopy of assembled Cu/Cu(111) adatom structures allows us to perform such studies with atomic-scale precision: starting from the discrete Cu adatom we observe the formation of a series of quantum states which merge into the traditional Shockley surface state in the limit of large islands. Our results show that there is a natural physical link between this archetype electronic surface property, the quantum confinement in compact adatom structures, and the sp_z hybrid state associated with the single adatom.

Three-dimensional plot of the topographic STM image of a compact triangular Cu₁₅/Cu(111) island (left) and spectroscopic image of the differential tunneling conductance dI/dV showing the wave function symmetry of a bound electronic quantum state (right).

J. Lagoute, X. Liu, and S. Fölsch, Link between Adatom resonances and the Cu(111) Shockley surface state, Phys. Rev. Lett. 95 (2005), 136801.