Theoretical study of electron states in Au chains on NiAl(110)

We have carried out a density functional study of unoccupied, resonance states in a single Au atom, dimers, a trimer and infinite Au chains on the NiAl(110) surface. Two inequivalent orientations of the ad-chains with substantially different interatomic distances were considered. From the study of the evolution of the electron states in an Au chain from being isolated to adsorbed, we find that the resonance states derive from the 6$s$ states of the Au atoms, which hybridize strongly with the substrate states and develop a $p$-like polarization. The calculated resonance states and LDOS images were analyzed in a simple tight-binding, resonance model. This model clarifies (1) the physics of direct and substrate-mediated adatom-adatom interactions and (2) the physics behind the enhancements of the LDOS at the ends of the adatom chains, and (3) the physical meaning of the "particle-in-box" model used in the analysis of observed resonance states. The calculated effective mass and band bottom energy are in good agreement with experimental data obtained from scanning tunnelling spectroscopy

Time Double-Slit Interference in Tunneling Ionization

We show that interference phenomena plays a big role for the electron yield in ionization of atoms by an ultra-short laser pulse. Our theoretical study of single ionization of atoms driven by few-cycles pulses extends the photoelectron spectrum observed in the double-slit experiment by Lindner et al, Phys. Rev. Lett. \textbf{95}, 040401 (2005) to a complete three-dimensional momentum picture. We show that different wave packets corresponding to the same single electron released at different times interfere, forming interference fringes in the two-dimensional momentum distributions. These structures reproduced by means of \textit{ab initio} calculations are understood within a semiclassical model.Comment: 7 pages, 5 figure

The luminosity function of the brightest galaxies in the IRAS survey

Results from a study of the far infrared properties of the brightest galaxies in the IRAS survey are described. There is a correlation between the infrared luminosity and the infrared to optical luminosity ratio and between the infrared luminosity and the far infrared color temperature in these galaxies. The infrared bright galaxies represent a significant component of extragalactic objects in the local universe, being comparable in space density to the Seyferts, optically identified starburst galaxies, and more numerous than quasars at the same bolometric luminosity. The far infrared luminosity in the local universe is approximately 25% of the starlight output in the same volume