Showing papers by "Colin Greaves published in 2008"
TL;DR: In this article, the authors measured the quantum efficiency of Cu(111) for different impinging light angles with photon energies just above the work function and observed that the vectorial photoelectric effect, an enhancement of the QE due to illumination with light with an electric vector perpendicular to the sample surface, is stronger in the more surface sensitive regime.
Abstract: The quantum efficiency (QE) of Cu(111) is measured for different impinging light angles with photon energies just above the work function. We observe that the vectorial photoelectric effect, an enhancement of the QE due to illumination with light with an electric vector perpendicular to the sample surface, is stronger in the more surface sensitive regime. This can be explained by a contribution to photoemission due to the variation in the electromagnetic potential at the surface. The contributions of bulk and surface electrons can then be determined.
13 citations
TL;DR: The local environments of cations in a recently reported δ-Bi2O3-related phase stabilised by erbium and rhenium, and which shows exceptionally high oxide ion conductivity at low temperatures, have been examined by Bi LIII-, Er LIII- and Re LIII edge extended X-ray absorption fine structure (EXAFS) measurements.
9 citations
TL;DR: In this article, a structural transition at 158 °C in Na0.63CoO2 is associated with a resistivity anomaly and it is suggested that the change in Na order is linked to a change in the electronic band structure, which is reflected in the resistivity anomalies.
Abstract: A structural transition at 158 °C in Na0.63CoO2 is associated with a resistivity anomaly. Raman spectroscopy suggests a change in Na ordering at the transition and, for the first time, we have identified the nature of this rearrangement using variable temperature neutron powder diffraction. On heating, some Na ions migrate to the thermodynamically less stable (Na1) site from Na2, consistent with loss of an incommensurate superstructure. It is suggested that the change in Na order is linked to a change in the electronic band structure, which is reflected in the resistivity anomaly.
7 citations
TL;DR: In this article, a mass-flow controlled reducing reaction was used to synthesize NdBaMnCoO{sub 5} and then low (800 deg. C) temperature oxidation was performed to produce ndBaNCoO {sub 6}.
4 citations
01 Jan 2008
TL;DR: The work of the photocathode R&D program at LBNL is presented in this article, where the quantum efficiency of Cu(111) is measured for different impinging light angles with photon energies just above the work function.
Abstract: The work of the photocathode R&D program at LBNL is presented. The quantum efficiency (QE) of Cu(111) is measured for different impinging light angles with photon energies just above the work function. We observe that the vectorial photoelectric effect, an enhancement of the quantum efficiency due to illumination of light with an electric vector perpendicular to the sample surface, is stronger in the more surface sensitive regime. This can be explained by a contribution to photoemission due to the variation of the electromagnetic potential at the surface. The contributions of bulk and surface electrons can then be determined. Angle-resolved photoemission data let us obtain the dispersion relation of the surface state, which in turn allows us to determine the thermal emittance of the electrons emitted from the surface.
1 citations