| 1. |
- Ablikim, M., et al.
(författare)
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Measurements of (XcJ)-> K+K-K+K- decays
- 2006
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Ingår i: Physics Letters B. - : Elsevier BV. - 0370-2693 .- 1873-2445. ; 642:3, s. 197-202
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Tidskriftsartikel (refereegranskat)abstract
- Using 14M psi(2S) events taken with the BESII detector, chi(cJ) -> 2(K+K-) decays are studied. For the four-kaon final state, the branching fractions are B(chi(c0,1,2) ->.2(K+K-)) = (3.48 +/- 0.23 +/- 0.47) x 10(-3), (0.70 +/- 0.13 +/- 0.10) x 10(-3), and (2.17 +/- 0.20 +/- 0.31) x 10(-3). For the phi K+K- final state, the branching fractions, which are measured for the first time, are B(chi(c0,1,2) -> phi K+K-) = (1.03 +/- 0.22 +/- 0.15) x 10(-3), (0.46 +/- 0.16 +/- 0.06) x 10(-3), and (1.67 +/- 0.26 +/- 0.24) x 10(-4). For the phi phi final state, B(chi(c0,2) -> phi phi) = (0.94 +/- 0.21 +/- 0.13) x 10(-3) and (1.70 +/- 0.30 +/- 0.25) x 10(-3).
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| 2. |
- Lu, Yuan-Yuan, et al.
(författare)
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A clinical study of microcirculatory disturbance in Chinese patients with sudden deafness
- 2008
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Ingår i: Acta Oto-Laryngologica. - : Informa UK Limited. - 0001-6489 .- 1651-2251. ; 128:11
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Tidskriftsartikel (refereegranskat)abstract
- Conclusion. Cochlear microcirculation disturbance is closely associated with sudden deafness. Objectives. To investigate the relationship between cochlear microcirculation and sudden deafness. Subjects and methods. Clinical laboratory parameters (clinical chemistry, hemorheology, hematology, and hemostasis determinations) were studied in 86 patients with sudden deafness and 30 healthy control subjects. Results. The levels of total cholesterol (TCH), triglyceride (TG), and lipoprotein A were significantly higher in patients with sudden deafness than in control subjects. Plasma viscosity, ratio viscosity of whole blood, reduced viscosity of whole blood, high and low shear relative viscosity of whole blood, index of red blood cells transmutation, and fibrinogen level in the plasma of patients with sudden sensorineural hearing loss (SSNHL) were also significantly elevated in comparison with those in control subjects. White-collar workers with psychological and behavioral abnormalities tend to suffer from sudden deafness.
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| 3. |
- Meng, Qing-Ling, et al.
(författare)
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Anatomic study of maximum intensity projection of the membranous labyrinth and the internal auditory meatus- MRI scan in 16 Chinese adults
- 2007
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Ingår i: Acta Oto-Laryngologica. - : Informa UK Limited. - 0001-6489 .- 1651-2251. ; 127:11, s. 1150-6
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Tidskriftsartikel (refereegranskat)abstract
- CONCLUSION: Three-dimensional reconstruction of maximum intensity projection (MIP) might document objectively, stereoscopically and directly the minute structures of the membranous labyrinth and internal auditory meatus. In this study, we establish magnetic resonance imaging (MRI) measurement criteria of the inner ear in Chinese adults.OBJECTIVE: The goal of this study was to provide an anatomic basis for otolosurgery and neurosurgery in Chinese adults.MATERIALS AND METHODS: Sixteen healthy volunteer subjects were scanned by a GE-signa 1.5T MRI scanner. All original images were transferred to an MRI workstation and all the structures of the inner ear were reconstructed, rotated at various angles and measured with an MIP program.RESULTS: Anatomic structures of the membranous labyrinth and internal auditory meatus were well demonstrated in MIP images in all volunteers. All inner ear structures including utricle, saccule, cochlear duct, internal auditory meatus and three semicircular ducts produced high intensity signals.
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| 4. |
- Gao, Shiwu, 1963, et al.
(författare)
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Emergence of collective plasmon excitation in a confined one-dimensional electron gas
- 2005
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Ingår i: PHYSICAL REVIEW B. ; 72:12, s. art. no. 121406-
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Tidskriftsartikel (refereegranskat)abstract
- We present a theoretical study of the electronic excitation in a confined one-dimensional electron gas, which is utilized to model atomic chains created in recent experiments. The length dependence of the excitation spectra is obtained from the linear response theory within the random phase approximation and time-dependent density functional theory. As the length of the chains increases, the dipole excitation spectra show a transition from electron-hole pair excitations to collective plasmon excitation. The trend of the length-dependent plasmon resonance is predicted, and the nature of the plasmon resonance is also elaborated.
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| 5. |
- Langhammer, Christoph, 1978, et al.
(författare)
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Plasmonic Properties of Supported Pt and Pd Nanostructures
- 2006
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Ingår i: Nano Letters. ; 6:4, s. 833-838
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Tidskriftsartikel (refereegranskat)abstract
- The plasmonic properties of nanodisk arrays of Pt, Pd, and, for comparison, Ag are studied over a large size and spectral range and analyzed theoretically by an electrostatic model. Pt and Pd nanodisks exhibit broad localized surface plasmons with a higher sensitivity of the plasmon to the disk aspect ratio compared to Ag. Extinction cross-sections are generally about 50% smaller for Pt and Pd. The spectral plasmon positions, line-widths, and extinction cross-sections are well reproduced by the model.
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| 6. |
- Yan, Jun, et al.
(författare)
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End and Central Plasmon Resonances in Linear Atomic Chains
- 2007
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Ingår i: Phys. Rev. Lett.. ; 98, s. 216602-
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Tidskriftsartikel (refereegranskat)abstract
- The existence and nature of end and central plasmon resonances in a linear atomic chain, the 1D analog to surface and bulk plasmons in 2D metals, has been predicted by ab initio time-dependent density functional theory. Length dependence of the absorption spectra shows the emergence and development of collectivity of these resonances. It converges to a single resonance in the longitudinal mode, and two transverse resonances, which are localized at the ends and center of the atom chains. These collective modes bridge the gaps, in concept and scale, between the collective excitation of atomic physics and nanoplasmonics. It also outlines a route to atomic-scale engineering of collective excitations.
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| 7. |
- Yuan, Zhe, 1981, et al.
(författare)
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Landau damping and lifetime oscillation of surface plasmons in metallic thin films studied in a jellium slab model
- 2008
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Ingår i: Surface Science. - : Elsevier BV. - 0039-6028. ; 602:2, s. 460-464
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Tidskriftsartikel (refereegranskat)abstract
- The lifetime of surface plasmons in metallic thin films has been calculated using linear response theory and time-dependent local density approximation. The linewidth due to Landau damping is found to depend exponentially on the film thickness. It exhibits quantum oscillations in ultrathin films with a period that is about three times longer than the universal period λF/2 observed in other quantities. This period results from the dynamical Friedel oscillations in the collective excitation normal to the films. Its finding has general implications in quantum control of nanoplasmons and their mediated processes across the films and on their surfaces.
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| 8. |
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| 9. |
- Yuan, Zhe, 1981, et al.
(författare)
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Linear-response study of plasmon excitation in metallic thin films: Layer-dependent hybridization and dispersion
- 2006
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Ingår i: PHYSICAL REVIEW B. ; 73:(15), s. 155411-
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Tidskriftsartikel (refereegranskat)abstract
- We present a theoretical study of collective plasmon excitation in metal thin films using the jellium model. The excitation spectra are calculated in the linear response theory and the time-dependent local density approximation. The evolution from surface plasmons at large thickness to the hybridized thin film plasmons at smaller thickness is obtained as functions of atomic layers and electron momenta. The energies of the hybridized plasmons follow qualitatively the classical electrodynamical model at large to intermediate thickness. For ultrathin films with a few atomic layers, these plasmon resonances evolve into intraband and interband transitions at small momenta. The latter results from the quantized electron states normal to the films.
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| 10. |
- Yuan, Zhe, 1981
(författare)
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Theoretical studies of collective electronic excitations in low-dimensional structures
- 2008
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- During the past decade, nanoplasmonics and nanophotonicshas emerged as a new branch of nanosciences with many novelapplications. Central in this development is the localized surface plasmon resonance (LSPR) tunable by the sizes and shapes at nanometer scale. These LSPRs are usually modeled by Maxwell's equations with dielectric functions of bulk materials. Classical modeling, though successful in reproducing plasmon frequencies, does not account for two effects: 1) space quantization in reduced dimensions; and 2) dynamical relaxation and dissipation near the surfaces.This thesis is dedicated to the theoretical study of collective electronic excitations in low-dimensional nanostructures using a fully quantum-mechanical description of electrons. It aims to gain knowledge and fundamental understanding on the space quantization and its interplay with electron dynamics at surfaces in reduceddimensions. Linear atomic chains and metallic thin films with tunable thickness were utilized as prototype structures for these purposes. Using both a confined one-dimensional electron gas model and atomistic description with pseudopotentials, we elaborated how the longitudinal collective resonance emerges and develops in short chains, and how it evolves into ``classical'' plasmon resonances inthe long chain limit. Two transverse modes, the central and end mode, were obtained and shown to be the 1D analog to the bulk and surface plasmons in 2D systems. In the case of thin films, the dispersions of the surface plasmons are classical like in thick films. Reducing the thickness, the antisymmetric mode starts to loss collective behavior and transforms to electron-hole-pair excitations in ultrathin films. The lifetimes of the surface plasmons due to Landau damping also show dynamical Friedel oscillations, which are unexpected from any classical models. The last part of this thesis was devoted to the development of a computational code for dynamical response of periodic systems starting from band structures. The thesis ends with application of this approach to the dynamical response for PdH$_x$. The absorption of hydrogen results in two purely electronic effects: 1) static charge localization, and 2) dynamical screening and depolarization with increasing concentration. These effects were elaborated by a real-space density analysis and explain unambiguously the observed redshift and broadening of the plasmon resonances of palladium upon absorption of hydrogen. The knowledge gained here on the model systems has far-reaching implications to the general understanding of surface-sensitive processes and their quantum dynamics in nanoplasmonics and nanophotonics.
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