Results of measurements of sulphur x-ray emission spectra of CuS and , excited by synchrotron radiation near the sulphur 2p threshold, are presented. An excitation energy dependence of the sulphur XES is only observed for CuS, and is attributed to the presence of inequivalent sulphur atoms in CuS. Two thirds of the sulphur atoms form dimers (as in ) while the remaining ones are single (as in ). This conclusion is confirmed by XPS measurements and LMTO band structure calculations for CuS, and . It is shown that selective excitation of x-ray emission valence spectra can be used to determine the atom-decomposed partial density of states for inequivalent sites in solids, occupied by chemically identical species.

This Letter proposes a characteristic length scale on surfaces and demonstrates its impact on nanorod growth. The proposed length scale is the dimension of a surface segment bounded by multiple-layer steps. Lattice kinetic Monte Carlo simulations, taking Cu as the prototype of nanorods, show that the proposed length scale (i) exists as the result of a diffusion barrier of adatoms down multiple-layer steps, (ii) dictates that the diameter of metallic nanorods is on the order of several hundred nanometers, and (iii) sets the upper limit of the facet dimension.

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The results of measurements of x-ray photoelectron ͑XPS͒, x-ray emission ͑XES͒, and x-ray absorption spectra and local spin-density approximation band structure ͑LSDA͒ calculations of Pr 0.5 Sr 0.5 MnO 3 are presented. The excitation energy dependence of Mn L 2,3 and O K␣ x-ray emission spectra of Pr 0.5 Sr 0.5 MnO 3 is measured using tunable synchrotron radiation. The XES measurements yielded no photon energy dependence for the O K␣ spectra, but the Mn L 2,3 spectra yielded inelastic scattering losses of 2 and 6 eV, corresponding to features in the structure of the occupied part of the valence band. Comparing XPS and XES measurements with LSDA band-structure calculations, one concludes that the electronic structure of the compound consists mainly of Mn 3d and O 2p states. States of 3d character localized at the Mn site predominate near the top of the valence band ͑VB͒. Some differences in the Mn 3d distribution in this part of the XPS valence band and Mn L 3 XES with d symmetry due to spin-selection rules that govern the Mn L 3 XES. In addition, the Mn 3d states distribution is hybridized with the O 2 p part of the VB. Mn L 3 XES spectra were determined relative to the Fermi energy by assuming normal x-ray emission begins from the lowest level of the p 5 d nϩ1 L intermediate state ͑which is the Mn 2p ionizatation threshold͒. From the local spin-density approximation, the orbital character of the Mn 3d electrons can be assigned e g symmetry at the top of the valence band T 2g in the central part of the VB, and equal contributions of e g and t 2g states at the bottom of the valence band.