Domain sensitive contrast in photoelectron emission microscopy.

We have investigated the adsorption of cesium on the Si(100) surface with photoelectron emission microscopy using linearly polarized green laser light. We observe a polarization dependent contrast between the (2 x 1) or (1 x 2) reconstructed terraces. Density-functional calculations reveal the geometric and electronic structure of the Cs/Si(100) surface. The contrast between the (2 x 1) or (1 x 2) reconstructed domains is explained on the basis of dipole selection rules for the photoemission matrix elements.

Ab initio simulation of the spin transition during chemisorption: H/Al(111).

Electronically nonadiabatic effects during the chemisorption of hydrogen atoms on an Al(111) surface are simulated ab initio using time-dependent density-functional theory for the electrons in combination with Ehrenfest dynamics for the nuclei. Strongly nonadiabatic effects close to the spin transition of the H atom are identified, and the dissipated energy as well as the electron-hole pair excitation spectra are calculated. The recent Newns-Anderson-model approach by Mizielinski et al. is confirmed. The simulations illustrate the physical processes that contribute to internal exoelectron emission.