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ABC effect in double-pionic nuclear fusion and a pn resonance as its possible origin

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Chinese Physics C 2010年第9期34卷 1339-1341页

作者： M.Bashkanov Physikalisches Institut Univ.Tübingen

A short overview over the ABC phenomenon is given,which is known since 50 years without any satisfactory explanation.On the basis of new exclusive and kinematically complete data obtained with the WASA detector at COSY we show that this phenomenon is linked with a resonant energy dependence in the total cross section of isoscalar double-pionic fusion processes.This resonance structure is connected with the baryon-baryon system,in particular with the pn and ΔΔ systems,however,has a mass,which is 90 MeV below the nominal ΔΔ threshold and a width of only 70 MeV,i.e.,five times smaller than expected from a conventional t-channel ΔΔ scenario.

关键词： ABC effect baryon-baryon resonance double-pionic fusion isoscalar resonance

Deeply virtual compton scattering at HERMES

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Chinese Physics C 2010年第9期34卷 1476-1478页

作者：俞伟林 Physikalisches Institut Justus-Liebig-Universitt Gieβen

Generalized Parton Distributions （GPDs） provide a way to access total angular momenta of partons and give a multidimensional picture of the nucleon structure.Deeply Virtual Compton Scattering （DVCS） is the most direct exclusive process to study GPDs.Different azimuthal cross-section asymmetries with respect to beam helicity,beam charge,and target polarization have been measured in the HERMES experiment.A recoil detector was installed at HERMES to directly detect the recoil proton.

关键词： compton scattering QCD nucleon structure

Ga_xIn_(1-x)P/AlGaInP多量子阱的吸收/反射光谱:多光束干涉的影响与消减

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Journal of Semiconductors 2004年第6期25卷 651-656页

作者：邵军 4 Physikalisches Institut

通过测量GaAs基GaxIn1-xP/AlGaInP多量子阱的光学吸收谱 ,揭示出采用吸收谱研究该量子阱系统所遭遇的困难 ,并判明吸收谱中高频振荡干扰的来源为多光束干涉 ,从而指出消减振荡干扰的有效途径在于降低量子阱样品的有效厚度 .提出了适用... 详细信息

通过测量GaAs基GaxIn1-xP/AlGaInP多量子阱的光学吸收谱 ,揭示出采用吸收谱研究该量子阱系统所遭遇的困难 ,并判明吸收谱中高频振荡干扰的来源为多光束干涉 ,从而指出消减振荡干扰的有效途径在于降低量子阱样品的有效厚度 .提出了适用于反射光谱测量的样品结构 ,并在实验中观察到激子跃迁 .通过对反射谱进行导数操作 ,达到了准确测定激子跃迁能量的目的。

关键词：吸收谱反射谱多量子阱多光束干涉谱导数

Acoustic plasmonics of Au grating/Bi2Se3 thin film/sapphire hybrid structures

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Chinese Physics B 2020年第6期29卷 49-53页

作者：李伟武 Konstantin Riegel 刘传普 Alexey Taskin Yoichi Ando 廖志敏 Martin Dressel 严缘 Physikalisches Institut Universitat StuttgartPfaffenwaldring 5770550 StuttgartGermany State Key Laboratory for Mesoscopic Physics School of PhysicsPeking UniversityBeijing 100871China Physics institute Ⅱ University of Cologne50937 KolnGermany Physikalisches Institut der Universitat Wurzburg 97074 WurzburgGermany institute for Topological Insulators 97074 WurzburgGermany

The surface plasmon polaritons of the topological insulator Bi2Se3 can be excited by using etched grating or grave structures to compensate the wave vector mismatch of the incident photon and plasmon. Here, we demonstrate novel gold grating/Bi2Se3 thin film/sapphire hybrid structures, which allow the excitation of surface plasmon polaritons propagating through nondestructive Bi2Se3 thin film with the help of gold diffractive gratings. Utilizing periodic Au surface structures,the momentum can be matched and the normal-incidence infrared reflectance spectra exhibit pronounced dips. When the width of the gold grating W(with a periodicity 2 W) increases from 400 nm to 1500 nm, the resonant frequencies are tuned from about 7000 cm-1 to 2500 cm-1. In contrast to the expected ■ dispersion for both massive and massless fermions,where q ~π/W is the wave vector, we observe a sound-like linear dispersion even at room temperature. This surface plasmon polaritons with linear dispersion are attributed to the unique noninvasive fabrication method and high mobility of topological surface electrons. This novel structure provides a promising application of Dirac plasmonics.

关键词： surface plasmon polaritons topological insulator infrared optoelectronics nanophotonics

The β-relaxation in metallic glasses

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National Science Review 2014年第3期1卷 429-461页

作者： Hai Bin Yu Wei Hua Wang Hai Yang Bai Konrad Samwer I. Physikalisches Institut Universit?t G?ttingen institute of Physics Chinese Academy of Sciences

Focusing on metallic glasses as model systems, we review the features and mechanisms of the β-relaxations,which are intrinsic and universal to supercooled liquids and glasses, and demonstrate their importance in understanding many crucial unresolved issues in glassy physics and materials science, including glass transition phenomena, mechanical properties, shear-banding dynamics and deformation mechanisms,difusion and the breakdown of the Stokes–Einstein relation as well as crystallization and stability of glasses.We illustrate that it is an atractive prospect to incorporate these insights into the design of new glassy materials with extraordinary properties. We also outline important questions regarding the nature ofβ-relaxations and highlight some emerging research directions in this still-evolving ield.

关键词： metallic glass β-relaxation glass transition shear transformation zone shear band difusion stability ultrastable glass

Photoproduction of ω-Mesons at ELSA and the role of azimuthal asymmetries

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Chinese Physics C 2009年第12期33卷 1146-1152页

作者： H. Schmieden Rheinische Friedrich-Wilhelms-Universitt Physikalisches Institut D-53115 Bonn Germany

Measurements of ω photoproduction of the Crystal-Barrel/TAPS experiment at the ELSA accelerator of Bonn University are presented which used linearly polarized tagged photon beam from threshold to Eγ = 1700MeV. The azimuthal asymmetries ∑and ∑πindicate s-channel resonance contributions on top of the established t-channel exchange processes. These findings are further enhanced by a very first measurement of the G-asymmetry which, in addition to the polarized photon beam, also requires a longitudinally polarized proton target. An intuitive interpretation of the specific sensitivity of the azimuthal asymmetries to the reaction mechanisms involved is given.

关键词： baryon resonances photoproduction vector mesons polarization

STABILIZATION, REFORMATION AND MELTING OF POLY(L-LACTIDE) CRYSTALLITES

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Chinese Journal of Polymer Science 2007年第1期25卷 83-94页

作者： Tai-Yon Cho Barbara Heck Gert Strobl Physikalisches Institut Albert-Ludwigs-Universitt Freiburg 79104 FreiburgGermany

The large size of the crystallites in poly（L-lactide） and the low growth rate enable detailed time- and temperaturedependent X-ray scattering studies of the ordering processes to be carded out. A layer located intermediate between crystals and melt-like regions is observed which finally takes on crystalline order. Recrystallization processes during heating change the complete stack structure rather than the crystallites individually and produce voids in the stacks, Establishment of a new stable structure after a temperature jump in the melting range can be followed in time. DSC experiments indicate times of melting of the order of minutes.

关键词： Poly（L-lactide） Polymer crystallization Small angle X-ray scattering Semicrystalline structure.

Dibaryons: Molecular versus compact hexaquarks

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Chinese Physics C 2021年第2期45卷 23-38页

作者： H.Clement T.Skorodko Physikalisches Institut der Universität Tübingen and Kepler Center for Astro and Particle Physics University of TübingenAuf der Morgenstelle 14D-72076 TübingenGermany

Hexaquarks constitute a natural extension of complex quark systems,just as tetra-and pentaquarks do.To this end,the current status of d^(*)(2380)in both experiment and theory is reviewed.Recent high-precision meas-urements in the nucleon-nucleon channel and analyses thereof have established d^(*)(2380)as an indisputable reson-ance in the long-sought dibaryon channel.Important features of this I(J^(P))=0(3^(+))state are its narrow width and deep binding relative to the 0(1232)0(1232)threshold.Its decay branchings favor theoretical calculations predict-ing a compact hexaquark nature of this state.We review the current status of experimental and theoretical studies on d^(*)(2380)as well as new physics aspects it may bring in future.In addition,we review the situation at the 0(1232)N and N^(*)(1440)N thresholds,where evidence for a number of resonances of presumably molecular nature has been found-similar to the situation in charmed and beauty sectors.Finally,we briefly discuss the situation of dibaryon searches in the flavored quark sectors.

关键词： dibaryon hexaquark molecule

Resistance switching in oxides with inhomogeneous conductivity

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Chinese Physics B 2013年第6期22卷 1-18页

作者：尚大山孙继荣沈保根 Wuttig Matthias Beijing National Laboratory for Condensed Matter Physics and institute of Physics Chinese Academy of Sciences I.Physikalisches Institut(IA) RWTH Aachen University

Electric-field-induced resistance switching （RS） phenomena have been studied for over 60 years in metal/dielectrics/metal structures. In these experiments a wide range of dielectrics have been studied including binary transition metal oxides, perovskite oxides, chalcogenides, carbon- and silicon-based materials, as well as organic materials. RS phenomena can be used to store information and offer an attractive performance, which encompasses fast switching speeds, high scalability, and the desirable compatibility with Si-based complementary metal-oxide-semiconductor fabrication. This is promising for nonvolatile memory technology, i.e., resistance random access memory （RRAM）. However, a comprehensive understanding of the underlying mechanism is still lacking. This impedes faster product development as well as accurate assessment of the device performance potential. Generally speaking, RS occurs not in the entire dielectric but only in a small, confined region, which results from the local variation of conductivity in dielectrics. In this review, we focus on the RS in oxides with such an inhomogeneous conductivity. According to the origin of the conductivity inhomogeneity, the RS phenomena and their working mechanism are reviewed by dividing them into two aspects： interface RS, based on the change of contact resistance at metal/oxide interface due to the change of Schottky barrier and interface chemical layer, and bulk RS, realized by the formation, connection, and disconnection of conductive channels in the oxides. Finally the current challenges of RS investigation and the potential improvement of the RS performance for the nonvolatile memories are discussed.

关键词： resistance switching inhomogeneous conductivity transition metal oxide