An x-pes study of the semiconductor-metal transition in NbO2

Marked changes in the Nb4d band in the X-ray photo-electron spectrum accompany the semiconductor-metal transition in NbO₂. The Nb4d band progressively shifts towards the O2p band with increase in temperature.     

X-ray and UV photoelectron spectra of the metal sesquioxides

He(I,II) and MgKα valence region photoelectron spectra of polycrystalline Ti₂O₃, V₂O₃, Cr₂O₃, Mn₂O₃, Fe₂O₃ and Rh₂O₃ have been recorded. The method of sample preparation employed gave rise to UV-PE spectra which are significantly different from those previously reported. While clear changes are observed in the spectra accompanying the semiconductor-to-metal transition of V₂O₃ at 150 K, there is no apparent modification of the Ti₂O₃ spectra accompanying its second order transition at 500 K. The remaining first row transition metal sesquioxides exhibit spectra indicative of localised 3d electrons.     

Template reactions with polynuclear complexes. The reaction of octachlorodimolybdate(II) with 2-aminobenzaldehyde

The binuclear molybdenum(II) anion [Mo₂Cl₈]^4? acts as a template for the self-condensation of 2-aminobenzaldehyde. The dimolybdenum unit is retained in the molybdenum(IV) product, [Mo₂(A)₂(H₂O)⁴⁺.4Cl^?, where A is a macrocyclic tetradentate ligand containing two Schiff base nitrogen donors. The product forms as two isomers, whose ¹H nmr spectra are discussed.     

Two centre continuum Coulomb wavefunctions in the entire complex plane

We solve the Schrödinger Equation for an electron moving in the Coulomb field of two charged nuclei. We take proper account of the analytic structure of the solutions and thus determine their mathematical form in the entire complex plane. These general solutions are then used to construct the two-centre analogue of the usual one-centre Coulomb wavefunctions.This work was supported by the Bundesministerium für Forschung und Technologie (BMFT), and by the Gesellschaft für Schwerionenforschung (GSI).     

A study of final state structure in the X-PE spectra of the rare-earth oxides Part II: Ionisation of a 4f electron

Valence region X-ray photoelectron spectra of the rare-earth oxides are reported and compared with spectra of the corresponding tris-dipivaloylmethide chelates. The results are interpreted with the aid of reported visible and UV absorption spectra and by recourse to the appropriate coupling model.     

Separation of metal cations in acidic solution by capillary electrophoresis with direct and indirect UV detection

Methods for the detectionn of metal cations under acidic conditions, near PH 2, in capillary electrophoresis (CE) were investigatged. Conditions for direct UV detection of UV absorbing metal cations such as Cr³⁺, Cu²⁺, Fe³⁺, UO₂²⁺, VO²⁺, and VO²⁺ were established With aqueous HCl or HClO₄ as the electroyte carrier. The speciation of vanadium(IV) and vanadium(V) at PH 2.3 by CE was achieved with direct detection at 185 nm. With the strong absorbance at 185 nm, no complexation was needed to detect the metal cations. An indirect UV detrection scheme for acidic conditions was also investigated. Several background carrier electolytes (BCES) were studied including 4-methylbenzylamince, nicontinamide, pyridazine, guanidine, 3-picoline, and chromium (III) to determine their effectivencess under very acidic conditions. The efect of ioni c surfactants and the nonionic surfactant, Trition X-100, on the peak heights and N Values was also studied.