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21.
We predict that in strongly localized mixed-valence systems “electronic” Raman scattering corresponding to transitions between the coupled potential surfaces can be comparable to or stronger than vibrational resonance Raman scattering. The characteristics of the two patterns depend sensitively on the parameters describing the system and the exciting frequency. 相似文献
22.
K. Bekk A. Andl S. Göring A. Hanser G. Nowicki H. Rebel G. Schatz 《Zeitschrift für Physik A Hadrons and Nuclei》1979,291(3):219-230
Isotope shifts and hyperfine structure of the BaI resonance-line (λ=553.6 nm) have been measured by dye laser induced resonance fluorescence on an atomic beam for135m, 129g, 129m, 126Ba thus extending previous high resolution measurements of neutron deficient Ba nuclides (N<82). The experimental results, now available for 16Ba isotopes and isomers withA=140?126, are used to deduce differences of rms charge radii, magnetic dipole and electric quadrupole moments. While the groundstates display a pronounced odd-even staggering the h 11/2? isomers135mBa and133mBa show a decreased staggering. Conspicuously the isomer shift of theg 7/2+ isomer129m Ba proves to be negative. The nuclear structure information is discussed in the context of gammaspectroscopic studies of transitional nuclei with 50<N,Z<82 and on the basis of a quasi-particle-plus-triaxial rotor model. The isotope shift discrepancy observed is fairly well described by the droplet model. 相似文献
23.
The temperature dependence of the electric field gradient for radiation-damaged copper and for the dilute alloy Zn has been measured using the perturbed angular correlation technique. A systematically weak temperature dependence is found for distorted cubic metals compared to non-cubic metals. The strong temperature dependence for the Zn, In and Sn alloys as reported in literature has not been confirmed in the present experiment. 相似文献
24.
S. N. Liddick P. F. Mantica R. V.F. Janssens B. A. Brown M. P. Carpenter A. D. Davies M. Honma M. Horoi T. Mizusaki A. C. Morton W. F. Mueller T. Otsuka J. Pavan H. Schatz A. Stolz S. L. Tabor B. E. Tomlin M. Wiedeking 《The European physical journal. Special topics》2007,150(1):135-136
We have utilized the selective process of β decay to
populate low-energy excited states in the neutron-rich 22Ti,
23V, 24Cr, and 25Mn nuclei. The goal was to systematically
track the monopole shift of the νf5/2 single-particle
level with increased occupancy of the πf7/2 orbital.
The β-decay properties of the parent nuclides, along
with the low-energy structure of the daughters, are
presented and compared with the results of shell model calculations
employing the GXPF1 interaction. 相似文献
25.
Alexander B. Weberg Subhajyoti Chaudhuri Thibault Cheisson Christian Uruburo Ekaterina Lapsheva Pragati Pandey Michael R. Gau Patrick J. Carroll George C. Schatz Eric J. Schelter 《Chemical science》2022,13(23):6796
The separation and purification of niobium and tantalum, which co-occur in natural sources, is difficult due to their similar physical and chemical properties. The current industrial method for separating Ta/Nb mixtures uses an energy-intensive process with caustic and toxic conditions. It is of interest to develop alternative, fundamental methodologies for the purification of these technologically important metals that improve upon their environmental impact. Herein, we introduce new Ta/Nb imido compounds: M(tBuN)(TriNOx) (1-M) bound by the TriNOx3− ligand and demonstrate a fundamental, proof-of-concept Ta/Nb separation based on differences in the imido reactivities. Despite the nearly identical structures of 1-M, density functional theory (DFT)-computed electronic structures of 1-M indicate enhanced basic character of the imido group in 1-Ta as compared to 1-Nb. Accordingly, the rate of CO2 insertion into the M Nimido bond of 1-Ta to form a carbamate complex (2-Ta) was selective compared to the analogous, unobserved reaction with 1-Nb. Differences in solubility between the imido and carbamate complexes allowed for separation of the carbamate complex, and led to an efficient Ta/Nb separation (STa/Nb = 404 ± 150) dependent on the kinetic differences in nucleophilicities between the imido moieties in 1-Ta and 1-Nb.A selective separation of the critical metals tantalum and niobium was accomplished from π-bonding-based reactivity differences of imido complexes. New insights into Ta/Nb separations were gained through detailed kinetic and computational studies. 相似文献
26.
M.A. Goetschalckx R.L. Mowery E.R. Krausz W.C. Yeakel P.N. Schatz B.S. Ault L. Andrews 《Chemical physics letters》1977,47(1):23-27
MCD measurements on XeF, XeCl, XeBr and XeI matrix isolated in Ar at low temperature are reported. Some relationships among the various spectroscopic parameters are established by combining these data existing absorption and ESR measurements. 相似文献
27.
E. Morenzoni M. Birke H. Glückler A. Hofer J. Litterst M. Meyberg C. Niedermayer Th. Prokscha G. Schatz Th. Wutzke 《Hyperfine Interactions》1997,106(1-4):229-235
At the Paul Scherrer Institute very slow, nearly 100% polarized, positive muons with an energy of \sim\mbox10 eV are produced
by moderating a secondary beam of surface muons in a thin film of an appropriate condensed gases. These epithermal muons can
be used as a source of a tertiary beam of tunable energy between \sim\mbox10 eV and \sim\mbox20 keV. Such a beam allows the
μSR technique to be extended to the study of thin films and surfaces.
In order to be able to perform time differential μSR experiments we have developed an ultra‐thin detector that registers the
passage of keV muons and permits to trigger the experiment. The results achieved so far demonstrate that first investigations
of thin film samples can be performed with the present set‐up.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
28.
29.
D.R. Demers J. Lei U. Shah P.M. Schoch K.A. Connor T.P. Crowley J.G. Schatz J.K. Anderson J.S. Sarff 《Czechoslovak Journal of Physics》2001,51(10):1065-1077
Measurement of the plasma potential in the core of MST marks both the first interior potential measurements in an RFP, as well as the first measurements by a Heavy Ion Beam Probe (HIBP) in an RFP. The HIBP has operated with (20-110) keV sodium beams in plasmas with toroidal currents of (200-480) kA over a wide range of densities and magnetic equilibrium conditions. A positive plasma potential is measured in the core, consistent with the expectation of rapid electron transport by magnetic fluctuations and the formation of an outwardly directed ambipolar radial electric field. Comparison between the radial electric field and plasma flow is underway to determine the extent to which equilibrium flow is governed by E×B. Measurements of potential and density fluctuations are also in progress.Unlike HIBP applications in tokamak plasmas, the beam trajectories in MST (RFP) are both three-dimensional and temporally dynamic with magnetic equilibrium changes associated with sawteeth. This complication offers new opportunity for magnetic measurements via the Heavy Ion Beam Probe (HIBP). The ion orbit trajectories are included in a Grad-Shafranov toroidal equilibrium reconstruction, helping to measure the internal magnetic field and current profiles. Such reconstructions are essential to identifying the beam sample volume locations, and they are vital in MST's mission to suppress MHD tearing modes using current profile control techniques. Measurement of the electric field may be accomplished by combining single point measurements from multiple discharges, or by varying the injection angle of the beam during single discharges.The application of an HIBP on MST has posed challenges resulting in additional diagnostic advances. The requirement to keep ports small to avoid introducing magnetic field perturbations has led to the design and successful implementation of cross-over sweep systems. High levels of ultraviolet radiation are driving alternative methods of sweep plate operation. While, substantial levels of plasma flux into the HIBP diagnostic chambers has led to the use of magnetic plasma suppression. 相似文献
30.
Banholzer MJ Li S Ketter JB Rozkiewicz DI Schatz GC Mirkin CA 《The journal of physical chemistry. C, Nanomaterials and interfaces》2008,112(40):15729-15734
We have developed a method to smooth the end sections of nanowires and nanograps generated via the On-Wire Lithography process and studied these rods with optical spectroscopies and theoretical modeling (Discrete Dipole Approximation). The first step of the smoothing process is a reductive one aimed at controlling the diffusion and migration of metal ions to the growing nanorod surface by adjusting the applied potential and concentration of the metal ions in the growth solution. A second oxidative smoothing step, based in part on the energetic differences between topologically rough and smooth surfaces, is used to further smooth the nanorod. The RMS roughness can be reduced over five fold to approximately 5 nm. The properties of these smoothed rods were investigated by empirical and theoretical methods, where it was found the smoothed rods have sharper plasmon resonances and decreased SERS intensity. 相似文献