Resonant Laser-Induced Desorption Of Metal Atoms: A Fully Relativistic Density-Functional Theory Study

Within full relativistic four-component ab initio density-functional calculations we studied the desorption of metal atoms induced by laser light. Recent experiments with K and Na nanoparticles showed a nonthermal resonant dependence of the desorption rate with respect to the applied photon energy without being accompanied by surface plasmon excitations. Using a cluster model of the metal surfaces we were able to identify localized electronic excitations and to calculate the corresponding energies that were in very good agreement with the experiments. We were able to explain the high desorption rates at these specific laser frequencies by localized electronic excitations that shift certain atoms to an antibonding potential energy curve causing the desorption.