Quantum-confinement effects in the conduction band of deposited germanium nanocrystals are measured to be greater than in similar-sized silicon nanocrystals. The germanium particles are condensed out of the gas phase and their electronic properties are determined with x-ray absorption spectroscopy. The conduction band edge shifts range from 0.2 eV for 2.7 nm particles up to 1.1 eV for 1.2 nm particles.

A scanned-energy mode photoelectron diffraction study of the Si͑100͒-͑2 3 1͒ surface with adsorbed NH 2 provides quantitative determination of key structural parameters previously only predicted from theoretical calculations. In particular, the N atoms occupy off-atop sites at a dimerized surface Si atom with N-Si bond lengths of 1.73 6 0.08 Å and bond angle relative to the surface normal of 21 ± 6 4 ± . The adsorption greatly reduces the Si dimer asymmetry relative to that of the clean surface.[ S0031-9007(97)03662-4]

Over the last few years it has been shown that information about the bulk band structure can be obtained by resonant inelastic X -ray scattering (RIXS) in the soft X -ray regime. However, conceptual differences exist about the underlying pictures involving keywords such as "resonant Xray emission" processes, "electronic resonant Raman scattering", and "core exciton formation". To understand and clarify the applicability of the different concepts, we have studied the properties of a new class of materials -beryllium chalcogenides (i.e., BeS, BeSe, and BeTe) -with soft X-ray K α emission following a resonant Be 1s core hole formation. Be chalcogenides constitute interesting candidates for several electronic applications of II-VIsemiconductors, e.g., in ZnSe-based blue light-emitting devices or Mn-containing spin aligner systems. We will show that even for such large band gap materials with an indirect gap, the observed spectral variations can be nicely correlated to the band structure derived from accompanying LDA-, EXX-, and GW-calculations taking the involved matrix elements into account. Furthermore, we observe Raman-like inelastic scattering features below the absorption threshold. Finally, "core excitonic" features above the valence band maximum can be observed for sufficiently high excitation energies. In the case of BeS, we will demonstrate that such information can even be obtained from insulating powder samples. The obtained results will be discussed in correlation with the above mentioned theoretical band structures, in view of the different conceptual approaches, and with a discussion of the underlying physical processes contributing to a loss of k-conservation and the appearance of a major non-coherent fraction in the observed spectra.The experiments were performed at beamline 8.0

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The electronic and chemical structure of Cu(In,Ga)(S,Se) 2 (CIGSSe) thin film surfaces and of relevant interfaces in CIGSSe-based thin film solar cells is investigated with a combination of X-ray emission spectroscopy (XES) and photoelectron spectroscopy. Examples of sulfur L 2,3 XES spectra of CdS and CIGSSe are discussed in view of resonant excitation, surface oxidation, and chemical bonding. The combination of the two techniques proves to be a powerful tool to identify spectral features correlated to certain chemical states or bonds. By monitoring these features in interface formation sequences, chemical and electronic information about buried interfaces can be obtained, which will be discussed in detail for the ZnO/CIGSSe interface. The experimental results provide valuable information on the CIGSSe surface and the ZnO/CIGSSe interface and, in general, demonstrate some of the spectroscopic advantages of X-ray emission spectroscopy.