The process of Fermi level equilibration in 5 nm ZnO quantum dot−metal nanojunctions has been monitored using changes to both the surface plasmon band of the metal island and the sharp exciton band of the ZnO nanocrystals following photoinduced electron accumulation. In the cases of silver, copper, and gold islands, excess electrons reside on both the quantum dot and the metal, whereas for Pt islands, the excess electrons reside exclusively on the Pt island. Electrons are transferred rapidly from Pt to the solvent ethanol, preventing accumulation on the quantum dots. The combination of exciton bleaching and surface plasmon shifts provides a simple way of probing the efficiency of small metal islands as redox catalysts on semiconductor particles.

Fermi Level Equilibration in Quantum Dot−Metal Nanojunctions†

XPS characterisation of in situ treated lanthanum oxide and hydroxide using tailored charge referencing and peak fitting procedures

The sorption of Eu(III) on anatase and rutile was studied as a function of ionic strength, humic acid (HA, 7.5 mg/L), and electrolyte anions over a large range of pH (2−12). The presence of HA significantly affected Eu(III) sorption to anatase and rutile. The sorption of Eu(III) on anatase and rutile was independent of ionic strength. Results of an X-ray photoelectron spectroscopy (XPS) analysis showed that Eu(III) was chemically present within the near-surface of TiO2 due to the formation of ≡SOEu and ≡SOHAEu complexes. An extended X-ray absorption fine structure (EXAFS) technique was applied to characterize the local structural environment of the adsorbed Eu(III), and the results indicated that Eu(III) was bound to about seven or eight O atoms at a distance of about 2.40 A. The functional groups of surface-bound HA were expected to be involved in the sorption process. The measured Eu−Ti distance confirmed the formation of inner-sphere sorption complexes on a TiO2 surface.

Eu(III) sorption to TiO2 (anatase and rutile): batch, XPS, and EXAFS studies.

Auger parameter and Wagner plot in the characterization of chemical states by X-ray photoelectron spectroscopy: a review

To identify the effect of humic acid (HA) and fulvic acid (FA) on the sorption mechanism of Eu(III) on organic--inorganic colloids in the environment at a molecular level, surface adsorbed/ complexed Eu(III) on hydrous alumina, HA-, and FA-hydrous alumina hybrids were characterized by using X-ray photoelectron spectroscopy (XPS) and time-resolved laser fluorescence spectroscopy (TRLFS). The experiments were performed in 0.1 mol/L KNO3 or 0.1 mol/L NaClO4 under ambient conditions. The pH values were varied between 2 and 11 at a fixed Eu(III) concentration of 6.0 x 10(-7) mol/L and 4.3 x 10(-5) mol/L. The different Eu(III)/FA(HA)/hydrous alumina complexes were characterized by their fluorescence emission spectra ((5D0-F1)/ (5D0 --> 7F2)) and binding energy of Eu(III). Inner-sphere surface complexation may contribute mainly to Eu(III) sorption on hydrous alumina, and a ternary surface complex is formed at the HA/ FA-hydrous alumina hybrid surfaces. The sorption and species of Eu(III) in ternary Eu-HA/FA-hydrous alumina systems are not dominated by either HA/FA or hydrous alumina, but are dominated by both HA/FA and hydrous alumina. The results are important for understanding the sorption mechanisms and the nature of surface adsorbed Eu(III) species and trivalent chemical homologues of Eu(III) in the natural environment.

Sorption of Eu(III) on humic acid or fulvic acid bound to hydrous alumina studied by SEM-EDS, XPS, TRLFS, and batch techniques.

The X-ray photoemission spectra of Nd(OH)3, Sm(OH)3, Eu(OH)3 and Gd(OH)3

The X-ray photoemission spectra of La(OH)3

A new nine-coordination system: Pentagonal interpenetrating tetrahedral polyhedron

The hydrous lanthanide oxides comprise a complicated series of both crystalline and amorphous compounds. The amorphous short-range-order (SRO) phase of hydrous erbium oxide is the subject of this work. A thorough discussion of the instrumental arrangement and electronic counting chain for the X-radiation diffraction data collection is included. The scattering profiles for hydrous erbium oxide are shown and details of the ensuing data correction procedures are given. A radial distribution analysis of the calculated interference function, Si(S), was performed. SRO interatomic distances and the first-shell coordination number are reported. The mean Er-O bond distance is found to be 2.36 A and the erbium metal is nine coordinated. Comparison of the experimental radial distribution curve to ones calculated from crystalline systems lend credibility to the experimentally determined distances.

http://journals.iucr.org/a/issues/1984/03/00/a23059/a23059.pdf

C.K.C. Lok

Papers

The X-ray photoemission spectra of Nd(OH)3, Sm(OH)3, Eu(OH)3 and Gd(OH)3

The X-ray photoemission spectra of La(OH)3

A new nine-coordination system: Pentagonal interpenetrating tetrahedral polyhedron

Short-range-order structure of amorphous hydrous erbium oxide

Electron spectroscopy for chemical analysis studies on oxyligated holmium compounds