Signature of carrier-induced ferromagnetism in Ti(1-x)Co(x)O(2-delta): exchange interaction between high-spin Co2+ and the Ti 3d conduction band

X-ray photoemission spectroscopy measurements were performed on thin-film samples of rutile Ti(1-x)Co(x)O(2-delta) to reveal the electronic structure. The Co 2p core-level spectra indicate that the Co ions take the high-spin Co2+ configuration, consistent with substitution on the Ti site. The high-spin state and the shift due to the exchange splitting of the conduction band suggest strong hybridization between carriers in the Ti 3d t(2g) band and the t(2g) states of the high-spin Co+2 . These observations support the argument that room temperature ferromagnetism in Ti(1-x)Co(x)O(2-delta) is intrinsic.     

Quality control of PET radiopharmaceuticals by high‐performance liquid chromatography with tris(2,2′‐bipyridyl)ruthenium(II) electrogenerated chemiluminescence detection

A highly sensitive reversed‐phase liquid chromatographic (HPLC) method was investigated to analyze a range of positron emission tomography (PET) radiopharmaceuticals using electrogenerated chemiluminescence (ECL) detection. ECL is based on the reaction of PET molecules with tris(2,2′‐bipyridyl)ruthenium(III) [Ru(bpy)₃³⁺], which is generated through the on‐line electro‐oxidation of Ru(bpy)₃²⁺. In 21 different radiopharmaceuticals studied, 18 compounds could be detected with detection limits (signal‐to‐noise ratio = 3) of 0.12–72 ng/mL per 20 μL injection. Sufficient reproducibility and linearity were obtained for the quantitative determination of PET molecules in pharmaceutical fluid. This method could be successfully applied to quality control tests of PET radiopharmaceuticals with ultra‐high specific radioactivity. Copyright © 2009 John Wiley & Sons, Ltd.     

Low Temperature CEMS of Corrosion Products by Sulfuric Acid Water

Conversion electron Mössbauer spectroscopy (CEMS) was used to study the corrosion products by sulfuric acid water. The acid water was put on the iron foil and evaporated under the atmosphere of several oxygen ratios in nitrogen-oxygen gas mixture in order to investigate the influence of oxygen contents on the corrosion products. The hyperfine fields of the observed sextets at 15 K suggest that the corrosion products consist of α-FeOOH, γ-FeOOH and γ-Fe₂O₃. The amount of γ-FeOOH becomes larger as the oxygen concentration increases. It is also found that the amount of γ-Fe₂O₃ becomes the largest at 1.4 % of the oxygen concentration.     

Synthesis and in vitro affinity for dopamine D-2 receptor of N-fluorine-substituted analogs of eticlopride

With the aim of developing fluorinated benzamides that may be useful as radioligands for positron emission tomography, fluorine analogs of eticlopride, in which the N-ethyl group was replaced by 2-fluoroethyl, 3-fluoropropyl and p-fluorobenzyl groups, were synthesized. These derivatives were tested for their ability to displace [3H]spiperone from its specific dopamine D-2 receptor. Their potencies were decreased when compared with eticlopride, but the two fluoroalkylated analogs were in the same order of magnitude as that of haloperidol.     

Application of X-ray fluorescence holography to the analysis of the interior and surface of an yttrium oxide thin film

We report on the characterization of a thin film of yttrium oxide by X-ray fluorescence holography. The sample has a layered structure with an YO base layer and an oxidized Y₂O₃ surface. Both layers are clearly observed in the atomic image reconstructions, and their local structure is analyzed. We show that by using incident energies close to the absorption edge of the fluorescing atom, it becomes possible to observe the thin surface layer clearly, even next to a base layer containing the same fluorescing element.     

Local magnetic measurements of composition-spread manganese oxide thin films with a scanning SQUID microscope

We performed scanning SQUID microscopic measurements on composition-spread La_1-xSr_xMnO₃ films deposited on various substrates. In thick films, the obtained local magnetic property as a function of x reproduces the bulk phase diagram well. In thin films (40 nm), we found that the phase boundaries significantly shifted depending on substrate materials. The stability of magnetic phases is discussed in term of the local strain associated with the lattice mismatch between film and substrate.     

Characteristics of mixed crystals Co(1−x)Fe x SO4· 7H2O

The characteristics of the mixed crystal (Fe,Co)SO₄·7H₂O (x=Fe/(Fe+Co)) are studied from the Mössbauer spectroscopy. They are quite similar atx>0.3 to those of FeSO₄·7H₂O. Whenx decreases from 0.2, the characteristics deviate from those of FeSO₄·7H₂O and approach gradually to those of CoSO₄·7H₂O.     

Formation and characterization of polyperinaphthalenic organic semiconductor nanoparticles by laser ablation of mixture targets of a perylene derivative with cobalt powder at 355 nm

Laser ablation of mixed targets of 3,4,9,10-perylenetetracarboxylic dianhydride (PTCDA) with cobalt powder (PTCDA-Co) was carried out using the third harmonic of a Nd:YAG laser (355 nm) in order to prepare nanoparticles consisting basically of polyperinaphthalene (PPN), a member of the low dimensional graphite family. The optimized content ratio of Co to PTCDA (Co:PTCDA) for effective elimination reaction of anhydride groups of PTCDA was determined. We found that the ablation at Co:PTCDA of 4:1 and 8:1 enabled us to eliminate the side groups effectively. Furthermore, surface enhanced Raman spectroscopy with a tip of an atomic force microscope was carried out to investigate the molecular structure of each nanoparticle. Amplification of the Raman intensity by more than 100 times compared with conventional micro Raman spectroscopy was achieved by tip enhancement. A nanoparticle having a diameter of approximately 70 nm prepared by this method was found to possess PPN structure. PACS 81.05.Uw; 81.16.Mk; 07.79.-v