Site-selective, resonant photochemical desorption of metal atoms with laser light: manipulation of metal surfaces on the atomic scale

Abstract

We have investigated non-thermal desorption of metal atoms using laser light in a wide wavelength range, i.e. from 355 to 1064 nm. Rough Na and K films served as model systems for bond breaking of Na and K atoms. The results demonstrate that localized electronic excitations on metal surfaces can be exploited to desorb atoms from a well-defined binding site. The desorption rate even depends resonantly on the applied photon energy making detachment site-selective. We also find that the reservoir from which atoms are released can be depleted and refilled repeatedly. Furthermore, the binding site depleted by desorption could be identified as fourfold coordinated adatoms on terraces by comparing the experimental data to the results of relativistic density functional calculations. The conclusions of this paper are not only of interest for the understanding of localized electronic states at metal surfaces but should also have essential impact for reducing the roughness of metal surfaces by manipulating and smoothing the topography with laser light on the atomic scale.