Electronic states localized at metal surfaces are of paramount importance for surface science due to their role in variety of phenomena such as chemical reactions at surfaces, molecular electronics, and magnetism of the layered structures. In this perspective, the possibility to design artificial structures with sought electronic properties, as offered by STM manipulation, is very attractive. Spectacular progress has been reached in the case of quantum corrals, where the discretization of the 2D surface state confined inside the corral leads to the appearance of well defined resonances in the electronic density of states [1]. Atomic wires aligned at the surface represent another example of STM build structure [2,3]. In difference to quantum corrals, the 1D periodicity is preserved along the wire allowing propagating states.
In this communication we present a theoretical study of the electronic states of Cu nanowires supported on a Cu(111) surface. A wave packet propagation approach is employed for the description of the electron dynamics, and the wire induced potential has been obtained from an ab initio density functional study [4,5].
Two kinds of electronic states are specific for the nanowire: (i) the 1D unoccupied band with sp character corresponding to the excited electron propagating along the wire, and (ii) the 1D band split off the 2D surface state continuum and corresponding to the nanowire-induced localization of the Shockley surface state. We have obtained the lifetimes and energy dispersion of the electronic (i) and (ii) bands. For the case of the 1D-sp-band the travel-along-the-wire distance of excited electrons is obtained as function of the energy of excited electron. Our results also allow a discussion on how the Scanning Tunneling Spectroscopy perturbs the electronic states of the nanowire (STM as a perturbing probe).
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[3] S. Fölsch et al, Phys. Rev. Lett. 92 (2004) 056803.
[4] A.G. Borisov, A.K. Kazansky and J.P. Gauyacq, Phys. Rev. B 59 (1999) 10935.
[5] F.E. Olsson et al, Phys. Rev. Lett. 93 (2004) 206803.
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