Unoccupied states of individual silver clusters and chains on Ag(111)

Size-selected silver clusters on Ag(111) were fabricated with the tip of a scanning tunneling microscope. Unoccupied electron resonances give rise to image contrast and spectral features which shift toward the Fermi level with increasing cluster size. Linear assemblies exhibit higher resonance energies than equally sized compact assemblies. Density functional theory calculations reproduce the observed energies and enable an assignment of the resonances to hybridized atomic 5s and 5p orbitals with silver substrate states.Comment: 9 pages, 8 figure

Photoelectron Spectroscopy of II-VI Semiconductor Heterostructures

We are growing ZnSe, ZnS and CdSe layers epitaxially on GaAs(001) substrates by atomic layer epitaxy and molecular beam epitaxy. The substrates are prepared by a H-plasma method in order to obtain a sharp interface between substrate and layer. The quality of our samples is controlled by reflection high energy diffraction and X-ray diffraction. Furthermore, the samples are characterized in situ by photoelectron spectroscopy. We observe resonant Zn 3d$\text{}^{8}$ and Cd 4d$\text{}^{8}$ satellites, which are used to check the layer quality. As a result, the valence band offsets of CdSe/ZnSe and ZnSe/CdSe were obtained. The values are ΔE$\text{}_{v}$(ZnSe/CdSe) = -(0.13 ± 0.07) eV and ΔE$\text{}_{v}$(CdSe/ZnSe) = -(0.13 ± 0.07) eV, which confirm the commutativity rule