Electronic confinement in two-dimensional metal nanostructures

There is a great deal of interest in size-specific cluster properties induced by coordination and confinement effects. In transition metals, for example, such effects lead to new electronic, magnetic, and catalytic properties. Surface-supported clusters consisting of only a few atoms provide an ideal model case to explore how electronic properties evolve with size. Assembled Cu/Cu(111) adatom islands of successive size represent an instructive case in this respect: starting from the discrete Cu atom 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.

Figure:

Three-dimensional plot of the topographic STM image (35 Å x 35 Å) of a compact triangular Cu/Cu(111) island consisting of 15 Cu atoms (left) and spectroscopic image of the differential tunneling conductance dI/dV showing the wave function symmetry of a bound electronic quantum state of the Cu₁₅ island (right).

Related publications:

J. Lagoute, X. Liu and S. Fölsch, Link between Adatom resonances and the Cu(111) Shockley surface state, Phys. Rev. Lett. 95, 136801-1/136801-4  (2005)