The syntheses of four new tungsten(V) dimeric thio-complexes with disulphido bridge are reported. The complexes have been identified by IR and electronic spectra, magnetic susceptibilities and analytical data. On the basis of the physical measurements we propose these complexes the following formula W2S4(Rdtc)2, where dtc = dithiocarbamate and R = morpholine, piperidine, N-ethylaniline and N,N-methylcyclohexyl. The low values of magnetic moments show a WW interaction. IR spectral results support a bidentate ligand behaviour and show a band in the 550-525 cm?1 region, that we attribute to a W S bond. 相似文献
In this work the magnetic and structural properties are investigated by Mössbauer spectrometry, Vibrating Sample Magnetometry and X-ray diffraction of Nd2(Fe100?xNbx)14B powdered alloys with x?=?0, 2 and 4 prepared by arc melting. The Mössbauer spectra of the samples were fitted with several contributions from: Nd2Fe14B, α-Fe and a paramagnetic phase associated with Nd1.1Fe4B4 for x?=?0 and additionally from NbFeB and Nd2Fe17 for x?=?2 and x?=?4. The relative fractions of α-Fe and Nd2Fe14B are smaller for x?=?4 than for x?=?0, indicating that the amount of these two phases is reduced with increasing Nb content, while the relative fraction of Nd2Fe17 increases. The α-Fe grain size slightly decreases while that of the Nd2Fe14B phase is increasing, when the Nb content increases. The hysteresis loops indicate that these samples behave as hard ferromagnets, with a coercive field which decreases when the Nb content increases, but with rather low remanent magnetization. 相似文献
NA60 is a fixed-target experiment at the CERN SPS which measured dimuon production in nucleus–nucleus and proton–nucleus collisions.
The experiment collected muon pair samples of unprecedented quality in heavy-ion experiments. This paper presents a high quality
measurement of the pT distribution of the φ meson, covering a broad pT window. The data were collected in 2003 in In-In collisions at 158 GeV per nucleon. The results, presented as a function
of centrality, were studied against several possible sources of systematic effects and proved to be fairly stable. We show
that the inverse mT slope measured in In-In collisions, in the φ→μμ decay channel, depends significantly on the range used to perform the fit.
When the fit is performed at low transverse momentum, the effective inverse slope increases from peripheral to central collisions,
as measured by other experiments. We finally show that our measurement for In-In is compatible with the overall systematics
of T slope versus mass, measured in different collision systems by the NA49 experiment
PACS 25.75.Nq; 25.75.-q; 25.75.Dw; 14.40.Cs; 12.38.Mh 相似文献
The optical properties of binary and ternary germanate glasses 40.3GeO2-59.7PbO, 31.3GeO2-26.8PbO-41.9Bi2O3 and 31.5GeO2-40.4PbO-28.1Bi2O3 (wt%) doped with Er3+ were investigated. The Judd-Ofelt intensity parameters were calculated and the near-infrared luminescence as well as the upconversion efficiency was analyzed. We observed that the ternary germanate glass containing the highest concentration of Bi2O3 presented the largest emission bandwidth for 4I13/2 → 4I15/2 transition and the highest infrared-to-visible upconversion efficiency among the samples studied. These results demonstrate that not only the presence of Bi2O3 but also the careful choice of its molecular weight plays a key role in optimizing parameters for using germanate glasses for photonics applications. 相似文献
We report results of a search for the lepton-family number violating decay K+-->pi(+)&mgr;(+)e(-) from data collected by experiment E865 in 1996 at the Alternating Gradient Synchroton of Brookhaven National Laboratory. We place an upper limit on the branching ratio at 3.9x10(-11) ( 90% C.L.). Together with results based on data collected in 1995 and an earlier experiment, E777, this result establishes a combined 90% confidence level upper limit on the branching ratio at 2.8x10(-11). We also report a new upper limit on the branching ratio for pi(0)-->&mgr;(+)e(-) of 3.8x10(-10) ( 90% C. L.). 相似文献
Summary: A novel class of polymer has been prepared by reaction of a copolyimide containing carboxylic acid groups, and a cobalt phthalocyanine peripherally substituted with a reactive hydroxyl group. The incorporation of the phthalocyanine ring was achieved by esterification of the carboxylic acid groups of the polyimide with the free hydroxyl group of the phthalocyanine. In this work, a limited number of phthalocyanine rings have been introduced in order to avoid extensive modification of the copolyimide properties. The extent of modification (percentage of esterified carboxylic groups) was estimated to be about 18%. The resulting material showed good thermal stability and a high glass transition temperature (above 300 °C). The incorporation of the bulky phthalocyanine ring brought about a light decrease of thermal properties, relative to those of the initial polyimide. The presence of phthalocyanine was confirmed by the absorption band at 670 nm showing in the visible region for the modified polyimide. The novel copolyimide also exhibited a remarkable emission peak at 430 nm, when excited at 350 nm, corresponding to the emission of the cobalt phthalocyanine moiety.
Schematic representation of the PI‐CoPc molecule and the chemical structure of the repeat unit. 相似文献