The surface valence-band densities of states (DOS) of Pt(3)M (M=Ti,V,Cr,Fe,Co,Ni) polycrystalline alloys were investigated with ultraviolet photoemission spectroscopy. Upon annealing the ion-sputter-cleaned alloys at high temperatures, the observed valence-band DOS spectra clearly show the modified electronic structures on the surfaces suggesting the surface segregation of Pt as predicted in thermodynamic models. The measured d-band centers and widths for the annealed alloy surfaces show qualitatively the same trend as predicted by density-functional-theory calculations based on the model of a Pt "skin" on the topmost surface layer and a subsurface layer enriched in the 3d transition metal.

The first elastic electron scattering has been successfully performed at the self-confining RI ion target (SCRIT) facility, the world's first electron scattering facility for exotic nuclei. The SCRIT technique achieved high luminosity (over 10 27 cm −2 s −1 , sufficient for determining the nuclear shape) with only 10 8 target ions. While 132 Xe used in this time as a target is stable isotope, the charge density distribution was firstly extracted from the momentum transfer distributions of the scattered electrons by comparing the results with those calculated by a phase shift calculation.The charge density distribution of the nucleus is one of the most important factors in the nuclear structure investigations, as it directly relates to the superimposition of the squared wave functions of all protons in the nucleus. Following the monumental measurements by R. Hofstadter and his colleagues [1] in the latter half of the 20th century, many stable nuclei have been studied by elastic electron scattering experiments. However, with few exceptions, electron scattering from short-lived unstable nuclei has been precluded by the difficulty in preparing the target material for these nuclei. Realizing electron scattering for unstable nuclei has been long waited, as it has been revealed that some of nuclei far from the stability valley exhibit exotic features such as neutron halo, neutron skin, etc.[2] which are totally unknown in stable nuclei.We have invented an internal target-forming technique called self-confining RI ion target (SCRIT) [3] in an electron storage ring, which three-dimensionally traps the target ions along the electron beam axis. The ions are confined by transverse focusing force given by the electron beam itself and an electrostatic potential well provided by electrodes put along the beam axis. After a successful feasibility study [4,5], we have recently completed the construction of the SCRIT electron scattering facility [6] at RIKEN's RI Beam Factory, which is dedicated to the study of exotic nuclei. The luminosity required for elastic electron scattering (10 27 cm −2 s −1 ) was achieved with only 10 8 target ions as available at an conventional isotope separation on line (ISOL) facility. In traditional electron scattering experiments, the number of target nuclei is typically of the order of 10 20 . This advancement enables electron scattering not only from unstable nuclei, but also from stable nuclei that have not been studied to date.In this Letter, we report the first elastic electron scattering results of 132 Xe nuclei obtained at the SCRIT facility. Although 132 Xe is a stable nucleus, it has never been investigated by electron scattering [7]. Interestingly, stable xenon isotopes have been recently utilized as targets for dark matter searches [8][9][10], and in neutrinoless double beta decay experiments [11]. To calculate the cross sections in these experiments, the form factors of the Xe isotopes are required. However, transition X-ray measurements of muonic atoms have yielded only the rootmean-squa...

Polarization dependence of soft-x-ray Raman scattering was investigated at the Ti 2p absorption edge of TiO 2 . Strong Raman scattering feature appears about 14 eV below elastic peaks with strong polarization dependence. These Raman scattering structures are charge transfer excitations to the antibonding state between 3d 1 L Ϫ1 and 3d 0 states, because they are enhanced when the incident photon energies are tuned at satellite structures of Ti 2p absorption spectrum. Broad Raman scattering structures are found between 3 eV and 10 eV below elastic peaks. They are assigned to be nonbonding type charge transfer excitations or interband transition from O 2p valence to Ti 3d conduction bands, which includes the crystal field splitting in D 2h symmetry with two Ti-O bond lengths.

Corrosion products formed on copper plates exposed in urban, rural/coastal, and hot spring areas in Japan were characterized by X-ray photoelectron spectroscopy, X-ray diffraction ͑XRD͒, and coulometric reduction. The exposure tests were carried out for a month in summer. XRD patterns showed that hydrated copper sulfate ͓Cu 4 SO 4 (OH) 6 •H 2 O, posnjakite͔ and cuprite Cu 2 O were formed on copper surfaces exposed in urban and rural/coastal areas. The existence of sulfate salt agrees well with the XPS spectra. Sulfur dioxide and particulate sulfate such as ammonium sulfate and sea salt are both possible origins of this sulfate. In contrast, XRD revealed that the only corrosion product formed on the copper exposed in the hot spring area was cuprite Cu 2 O, although the amount of sulfur on the surface of this sample was the highest. Coulometric reduction analysis showed that there was copper sulfide Cu 2 S in corrosion products formed on copper exposed in the hot spring area. Posnjakite Cu 4 SO 4 (OH) 6 •H 2 O is initially formed in addition to cuprite Cu 2 O when copper is exposed in urban and rural/coastal atmospheres. This crystalline phase is located at and near the copper surface. Initially formed posnjakite Cu 4 SO 4 (OH) 6 •H 2 O may change to brochantite Cu 4 SO 4 (OH) 6 , which is a typical patina component that appears after further exposure.

Two-dimensional electrons in a magnetic field can form new states of matter characterized by topological properties and strong electronic correlations as displayed in the integer and fractional quantum Hall states. In these states, the electron liquid displays several spectacular characteristics, which manifest themselves in transport experiments with the quantization of the Hall resistance and a vanishing longitudinal conductivity or in thermodynamic equilibrium when the electron fluid becomes incompressible. Several experiments have reported that dissipationless transport can be achieved even at weak, non-quantizing magnetic fields when the electrons absorb photons at specific energies related to their cyclotron frequency. Here we perform compressibility measurements on electrons on liquid helium demonstrating the formation of an incompressible electronic state under these resonant excitation conditions. This new state provides a striking example of irradiation-induced self-organization in a quantum system.

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Articles you may be interested inSilicon nanocrystals with high boron and phosphorus concentration hydrophilic shell-Raman scattering and Xray photoelectron spectroscopic studies

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