Energy Dependence of Cu L2,3 Satellites using Synchrotron Excited X-ray Emission Spectroscopy

The L2,3 X-ray emission of Cu metal has been measured using monochromatic synchrotron radiation. The self-absorption effect in the spectra is shown to be very small in our experimental geometry. From the quantitative analysis of spectra recorded at different excitation energies, the L3/L2 emission intensity ratio and the partial Auger-width are extracted. High-energy satellite features on the L3 emission line are separated by a subtraction procedure. The satellite intensity is found to be slowly increasing for excitation energies between the L3, L2 and L1 core-level thresholds due to shake-up and shake-off transitions. As the excitation energy passes the L2 threshold, a step of rapidly increasing satellite intensity of the L3 emission is found due to additional Coster-Kronig processes.Comment: 8 pages, 3 figures, http://link.aps.org/doi/10.1103/PhysRevB.56.1223

The Relationship Between Career Paths, Institutional Types, Demogrophics and the Operational Frameworks of College and University Presidents

Leadership is an elusive quality sought by many individuals and organizations. As organizations become more complex, the search for effective leadership intensifies. Presidents of universities and colleges were, historically, identified as the key leaders on campuses, in their own states, and nationally, able to raise institutions to greatness or drag them into mediocrity through the sheer force of their personality and efforts. More recent research suggests that college and university presidents have far less to do with the success of an institution than previously thought. Some presidents are somewhat successful by adapting their leadership frames through understanding the environment and culture of the institution they currently lead. Researchers have suggested that leaders “frame” their understanding of the organizations they lead in four ways: structural, human resource, political, and symbolic. This study sought to determine if there were relationships to be found among presidents\u27 backgrounds and career experience that would indicate a pattern of leadership frame(s) correlating to common backgrounds and careers. These data could then identify which backgrounds and career paths led to the type(s) of institutions a president would most likely lead. Demographic and career background data were collected and compared against data collected from the participants that identified their most common operational frame. The survey collected demographic data from the participants to strengthen validity. The survey instrument identified the participants\u27 dominant personal frame(s) (a majority of leaders operate from at least two, and usually three frames), that they used to gather information, make decisions, and get things done. It also determined if there were relationships among presidents\u27 backgrounds and career experience that would have indicated a pattern of leadership frames correlated with common backgrounds and careers. The demographic data in this study closely mirrored national data from other recent studies. The largest number of presidents operated primarily from a symbolic frame. Almost 40% of all presidents operated from at least three of four frames when compared to others in the study. Previous career experience being a Student Services Vice-President was negatively related to selection as president of Doctoral/Research and Master\u27s institutions. Previous career experience as a department Chair was positively related to selection as president of Doctoral/Research and Master\u27s institutions and negatively related to selection as president of Associate and Other institutions

X-ray fluorescence spectra of metals excited below threshold

X-ray scattering spectra of Cu and Ni metals have been measured using monochromatic synchrotron radiation tuned from far above to more than 10 eV below threshold. Energy conservation in the scattering process is found to be sufficient to explain the modulation of the spectral shape, neglecting momentum conservation and channel interference. At excitation energies close to and above threshold, the emission spectra map the occupied local partial density of states. For the sub-threshold excitations, the high-energy flank of the inelastic scattering exhibits a Raman-type linear dispersion, and an asymmetric low energy tail develops. For excitation far below threshold the emission spectra are proportional to a convolution of the occupied and unoccuppied local partial densities of states.Comment: 10 pages, 3 figures, http://link.aps.org/doi/10.1103/PhysRevB.68.04511

Ecological Significance of a Drifting Object to Pelagic Fishes

Volume: 21Start Page: 486End Page: 49

Magnetic circular dichroism in X-ray fluorescence of Heusler alloys at threshold excitation

The results of fluorescence measurements of magnetic circular dichroism (MCD) in Mn L_2,L_3 X-ray emission and absorption for Heusler alloys NiMnSb and Co2MnSb are presented. Very intense resonance Mn L_3 emission is found at the Mn 2p_3/2 threshold and is attributed to a peculiarity of the threshold excitation in materials with the half-metallic character of the electronic structure. A theoretical model for the description of resonance scattering of polarized x-rays is suggested.Comment: 3 pages, 2 figures. Discussed at conferences, submitting process in progres

Electronic structure and chemical bonding of nc-TiC/a-C nanocomposites

The electronic structure of nanocrystalline (nc-) TiC/amorphous C nanocomposites has been investigated by soft x-ray absorption and emission spectroscopy. The measured spectra at the Ti 2p and C 1s thresholds of the nanocomposites are compared to those of Ti metal and amorphous C. The corresponding intensities of the electronic states for the valence and conduction bands in the nanocomposites are shown to strongly depend on the TiC carbide grain size. An increased charge-transfer between the Ti 3d-eg states and the C 2p states has been identified as the grain size decreases, causing an increased ionicity of the TiC nanocrystallites. It is suggested that the charge-transfer occurs at the interface between the nanocrystalline TiC and the amorphous C matrix and represents an interface bonding which may be essential for the understanding of the properties of nc-TiC/amorphous C and similar nanocomposites.Comment: 13 pages, 6 figures, 1 table; http://link.aps.org/doi/10.1103/PhysRevB.80.23510