A simple theoretical derivation of the maximum cross-talk isolation achievable in full-duplex single-strand multi-mode fiber-optic systems operating at a single wavelength is performed. For a commercial fiber of 1 km length with a total attanuation of 8 dB/km and a NA of 0.16, the measured cross-talk isolation was 42 dB for a single 130 ns, 0.9 μm pulse in agreement with the theory. 相似文献
Search for baryon pairs production ine+e? annihilation at \(\sqrt s = 2386 MeV\) is reported. The data relate to a luminosity of 161 nb?1 collected by the DM2 experiment at DCI, the Orsay colliding ring. First measurements of directe+e? annihilation into \(\Lambda \bar \Lambda \) and ofe+e?→ \(p\bar p\) at this energy are presented. First observation of a goode+e?→ \(n\bar n\) candidate is reported and upper limits are given fore+e?→ \(n\bar n, \Lambda \bar \sum ^0 + c.c.\) and \(\Sigma ^0 \bar \Sigma ^0 \) . 相似文献
We consider a class of elliptic random matrices which generalize two classical ensembles from random matrix theory: Wigner matrices and random matrices with iid entries. In particular, we establish a central limit theorem for linear eigenvalue statistics of real elliptic random matrices under the assumption that the test functions are analytic. As a corollary, we extend the results of Rider and Silverstein (Ann Probab 34(6):2118–2143, 2006) to real iid random matrices. 相似文献
Rollover cyclometalated complexes constitute a family of derivatives which differ from classical cyclometalated species in certain aspects. Various potential application fields have been developed for both classes of compounds, which have both similarities and differences. In order to uncover the relationships and distinctions between these two families of compounds, four Pt(II) cyclometalated complexes derived from 2-phenylpyridine (ppy) and 2,2′-bipyridine (bpy), assumed as prototypical ligands, were compared. For this study, an electron rich isostructural and isoelectronic pair of compounds, [Pt(N^C)Me(PPh3)], and an electron-poorer compound, [Pt(N^C)Cl(PPh3)] were chosen (N^C = ppy or bpy). DFT calculations, cyclic voltammetry, and UV-Vis spectra also helped to shed light into these species. Due to the presence of the more electronegative nitrogen in place of a C-H group, the rollover bpy-H ligand becomes a slightly weaker donor than the classical ppy-H ligand, and hence, generates (slightly) more stable cyclometalated complexes, lower energy frontier molecular orbitals, and electron-poorer platinum centers. On the whole, it was revealed that classical and rollover complexes have overall structural similarity, which contrasts to their somewhat different chemical behavior. 相似文献
Sharp resonant structures in the cross section of the atomic electron-ion collision process of dielectronic recombination are exploited to study isotope shifts and hyperfine interaction of heavy highly-charged ions. This novel approach provides a conceptual alternative to existing methods. In this contribution, we present a series of measurements, which we performed at the heavy ion storage ring ESR of the GSI Helmholtzzentrum für Schwerionenforschung, Darmstadt, Germany. In a first experiment the stable isotopes A = 142 and A = 150 of three-electron neodymium ANd57?+? were studied. Isotope shifts of dielectronic resonances associated with 2s???2pj (j?=?1/2, 3/2) transitions were extracted from the measured data. The evaluation of the energy shift was performed within a full QED framework and yielded a change in the mean-square charge radius of $^{142,150}\delta \langle r^2 \rangle = -1.36(1)(3)$ fm2. At GSI, in addition to the investigation of stable isotopes unstable species can be artificially synthesized and studied. Radioisotopes produced in-flight from fragmentation of a 238U primary beam were injected into the ESR and were subsequently separated by their mass-to-charge ratio. This enabled us to perform first DR experiments with the exotic nuclei 237U89?+? (Z = 92 )and 234Pa88?+? (Z = 91). 相似文献
Matrix assisted laser desorption ionization imaging mass spectrometry (MALDI-IMS) is a technique that has seen a sharp rise in both use and development. Despite this rapid adoption, there have been few thorough investigations into the actual physical mechanisms that underlie the acquisition of IMS images. We therefore set out to characterize the effect of IMS laser ablation patterns on the surface of a sample. We also concluded that the governing factors that control spatial resolution have not been correctly defined and therefore propose a new definition of resolution.
13 C NMR spectroscopy as well as the short bond between the platinum and the C4 atom of the pyridine ring in 1 (1.95 Å) indicate the formation of a novel carbene species. Compound 1 is remarkably stable (m.p. 246°C), probably due to the presence of intramolecular hydrogen bonds, and is formed instead of the expected cyclometalated product. R=n-hexyl. 相似文献