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INVESTIGATION ON ThE VALENCE STATE OF Ce ATOMIN BULK AND NANOCRYSTAL CeO_2 BY X-RAY ABSORPTION ANDPhOTOEMISSION

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Acta Metallurgica Sinica(English Letters) 2001年第6期14卷 511-516页

作者： K. Ibrahim, Z.Y. Wu, j. Zhang, M.I. Abbas, F.Q. Liu and h.j. qian (Beijing Synchrotron Radiation Laboratory, Institute of high Energy Physics, The Chinese Academy of Sciences, P.O. Box 918, Beijing 100039, China) Beijing Synchrotron Radiat. Lab. Inst. of High Energy Phys. Chinese Acad. of Sci. P.O. Box 918 Beijing 100039 China

Valence band photoemission spectra (PES) for both bulk and nanocrystal CeO2 have been measured on and off resonance of Ce 4d-4f absorption edge. The PES show that the bulk and nanocrystal CeO2 of diameter ranging from 8nm to 50nm exhibit a peak near Fermi edge with binding energy of about 1.8eV. The 1.8eV peak shows a strong dependence on excitation energy, although it looks like the contribution of Ce3+ ion following the data reported in literatures. however, according to the results of resonance photoemission and X-ray absorption spectra at 1s edge, this electronic structure may be associated to the intermediate state charge transfer effects.

关键词： rare earth oxide photoemission electronic structure photoabsorption

RESONANT PhOTOEMISSION OF BULK CeO_(2) AND NANO-CeO_(2) FILMS

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Acta Metallurgica Sinica(English Letters) 2001年第6期14卷 539-543页

作者： M.I. Abbas, K. Ibrahim, Z.Y. Wu, j. Zhang, F.Q. Liu and h.j. qian (Beijing Synchrotron Radiation Laboratory, Institute of high Energy Physics, The Chinese Academy of Sciences, P.O. Box 918, Beijing 100039, China) Beijing Synchrotron Radiat. Lab. Inst. of High Energy Phys. Chinese Acad. of Sci. P.O. Box 918 Beijing 100039 China

Photoemission behaviors of nano-CeO2 films with particle sizes ranging from 8 nm to 50 nm and bulk CeO2 in Ce 4 d-4 f absorption region have been investigated. Resonant enhancements of Ce 4 f valance band and Ce 5 p bands for nano film and bulk material have been observed. The variation of electron density of states in valance bands of nano and bulk structures of CeO2 is discussed in terms of Ce 4 d-4 f resonance.

关键词： Nanostructured materials Optical films Oxides Photoemission Resonance

INVESTIGATION OF BONDING IN NANO-SiO_(2) BY Si L_(2,3) X-RAY ABSORPTION NEAR-EDGE STRUCTURE SPECTROSCOPY

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Acta Metallurgica Sinica(English Letters) 2001年第6期14卷 473-478页

作者： Z.Y. Wu, K. Ibrahim, G. Li, j. Zhang, F.Q. Liu, M.I Abbas, R. hu, h.j. qian and F.Q. Tang ( Beijing Synchrotron Radiation Facility, Institute of high Energy Physics, The Chinese Academy of Sciences, Beijing 100039, China) ( Laboratori Nazionali di Frascat Inst. of high Energy Phys. Chinese Acad. of Sci. Beijing 100039 China

The Si L2,3 X-ray absorption near-edge structure (XANES) can be used to probe thelocal structure around Si and derive electronic information of the unoccupied s- andd-like partial density of states in nano-size SiO2. We present Si L2,3-edge for threedifferent size silicates acquired by total electron yield (TEY) at the photoemission sta-tion of Beijing Synchrotron Radiation Facility (BSRF). The Si L2,3-edge spectra areinterpreted based on ab initio full multiple-scattering (MS) calculation. The Si L2.3-edge of nano-size materials has XANES similar to that of a-quartz. The similaritiesbetween the Si L2.3-edge shapes attest to a common molecular-orbital picture of theirSi-O bonding and the same coordination state. however, a considerable broadeningof Si L2,3-edge XANES spectra as decrease of particle size is also an indicative ofpolyhedral distortions.

关键词： multiple scattering calculation X-ray absorption nano particle electronic structure

Network Embedding Algorithm for Vulnerability Assessment of Power Transmission Lines Using Integrated Structure and Attribute Information

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CSEE journal of Power and Energy Systems 2024年第1期10卷 351-360页

作者： Xianglong Lian Tong qian Zepeng Li Xingyu Chen Wenhu Tang Q.h.Wu School of Electric Power Engineering South China University of TechnologyGuangzhou 510640China

In power systems,failures of vulnerable lines can trigger large-scale cascading failures,and vulnerability assessment is dedicated to locating these lines and reducing the risks of such *** on a structure and attribute network embedding(SANE)algorithm,a novel quantitative vulnerability analysis method is proposed to identify vulnerable lines in this ***,a two-layered random walk network with topological and electrical properties of transmission lines is ***,based on the weighted degree of nodes in the two-layered network,the inter-layer and intra-layer walking transition probabilities are developed to obtain walk ***,a Word2Vec algorithm is applied to obtain lowdimension vectors representing transmission lines,according to obtained walk sequences for calculating the vulnerability index of transmissions ***,the proposed method is compared with three widely used methods in two test *** show the network embedding based method is superior to those comparison methods and can provide guidance for identifying vulnerable lines.

关键词： Network embedding random walk transmission lines vulnerability assessment

Localizing vitamin-C through nanoconfinement enables high-rate CO_(2) electrolysis to ethylene

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Science China Materials 2024年第3期67卷 1006-1008页

作者： Zhengyi qian Shaojun Guo School of Materials Science and Engineering Peking UniversityBeijing 100871China

The electrosynthesis of value-added fuels and chemicals from carbon dioxide reduction reaction(CO_(2)RR)is a promising approach for realizing the objectives of carbon neutrality[1].Nevertheless,the current production of desirable multicarbon(C_(2+))chemicals,such as ethylene(C_(2)h_(4)),still encounters challenges related to low selectivity,low current density,and the requirement for high-purity feeding gas[2].

关键词： enable purity dioxide

Existence and asymptotics of normalized solutions for the logarithmic Schrödinger system

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Science China Mathematics 2024年第9期67卷 2019-2048页

作者： qian Zhang Wenming Zou Department of Mathematical Sciences Tsinghua UniversityBeijing 100084China

This paper is concerned with the following logarithmic Schrodinger system:{-Δu_(1)+ω_(1)u_(1)=u_(1)u_(1)logu_(1)^(2)+2p/p+q|u_(2)|^(q)|u_(1)|^(p-2)u_(1),-Δu_(2)+ω_(2)u_(2)=u_(2)u_(2)log u_(2)^(2)+2q/p+q|u_(1)|^(p)|u_(2)|^(q-2)u_(2),∫_(Ω)|u_(i)|^(2)dx=ρ_(i),i=1,2,(u_(1),u_(2))∈h_(0)^(1)(Ω;R^(2)),where Ω=R^(N)or Ω■R^(N)(N≥3)is a bounded smooth domain,andω_(i)R,μ_(i),ρ_(i)>0 for i=1,***,p,q≥1,and 2≤p+q≤2^(*),where 2^(*):=2N/*** using a Gagliardo-Nirenberg inequality and a careful estimation of u log u^(2),firstly,we provide a unified proof of the existence of the normalized ground state solution for all 2≤p+q≤2^(*).Secondly,we consider the stability of normalized ground state ***,we analyze the behavior of solutions for the Sobolev-subcritical case and pass to the limit as the exponent p+q approaches 2^(*).Notably,the uncertainty of the sign of u log u^(2)in(0,+∞)is one of the difficulties of this paper,and also one of the motivations we are interested *** particular,we can establish the existence of positive normalized ground state solutions for the Brézis-Nirenberg type problem with logarithmic perturbations(i.e.,p+q=2^(*)).In addition,our study includes proving the existence of solutions to the logarithmic type Bréis-Nirenberg problem with and without the L^(2)-*** ∫_(Ω)|u_(i)|^(2)dx=ρ_(i)(i=1,2)by two different methods,*** results seem to be the first result of the normalized solution of the coupled nonlinear Schrodinger system with logarithmic perturbations.

关键词： logarithmic Schrodinger system Brézis-Nirenberg problem normalized solution existence and stability behavior of solutions

Luminescence regulation of Sb^(3+)in 0D hybrid metal halides by hydrogen bond network for optical anti-counterfeiting

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Opto-Electronic Advances 2024年第3期7卷 15-25页

作者： Dehai Liang Saif M.h.Qaid Xin Yang Shuangyi Zhao Binbin Luo Wensi Cai Qingkai qian Zhigang Zang Key Laboratory of Optoelectronic Technology&Systems(Ministry of Education) Chongqing UniversityChongqing 400044China Department of Physics&Astronomy College of SciencesKing Saud UniversityP.O.Box 2455Riyadh 11451Saudi Arabia Department of Chemistry and Chemical Engineering Key Laboratory for Preparation and Application of Ordered Structural Materials of Guangdong ProvinceShantou UniversityShantou 515063China Department of Oil Army Logistics Academy of PLAChongqing 401311China

The Sb^(3+) doping strategy has been proven to be an effective way to regulate the band gap and improve the photophysical properties of organic-inorganic hybrid metal halides(OIhMhs).however,the emission of Sb^(3+) ions in OIhMhs is primarily confined to the low energy region,resulting in yellow or red *** date,there are few reports about green emission of Sb^(3+)-doped ***,we present a novel approach for regulating the luminescence of Sb^(3+) ions in 0D C_(10)h_(2)_(2)N_(6)InCl_(7)·h_(2)O via hydrogen bond network,in which water molecules act as agents for hydrogen ***^(3+)-doped C_(10)h_(2)2N_(6)InCl_(7)·h_(2)O shows a broadband green emission peaking at 540 nm and a high photoluminescence quantum yield(PLQY)of 80%.It is found that the intense green emission stems from the radiative recombination of the self-trapped excitons(STEs).Upon removal of water molecules with heat,C_(10)h_(2)_(2)N_(6)In_(1-x)Sb_(x)Cl_(7) generates yellow emis-sion,attributed to the breaking of the hydrogen bond network and large structural distortions of excited *** water molecules are adsorbed by C_(10)h_(2)_(2)N_(6)In_(1-x)Sb_(x)Cl_(7),it can subsequently emit green *** water-induced reversible emission switching is successfully used for optical security and information *** findings expand the under-standing of how the local coordination structure influences the photophysical mechanism in Sb^(3+)-doped metal halides and provide a novel method to control the STEs emission.

关键词： indium-based halides Sb^(3+)doping hydrogen bonding network optical anti-counterfeiting

Sequential good lattice point sets for computer experiments

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Science China Mathematics 2024年第9期67卷 2153-2170页

作者： Xue-Ru Zhang Yong-Dao Zhou Min-qian Liu Dennis K.j.Lin NITFID LPMC&KLMDASRSchool of Statistics and Data ScienceNankai UniversityTianjin 300071China Department of Statistics Purdue UniversityWest LafayetteIN 47907USA

Sequential Latin hypercube designs(SLhDs) have recently received great attention for computer experiments, with much of the research restricted to invariant spaces. The related systematic construction methods are inflexible, and algorithmic methods are ineffective for large designs. For designs in contracting spaces, systematic construction methods have not been investigated yet. This paper proposes a new method for constructing SLhDs via good lattice point sets in various experimental spaces. These designs are called sequential good lattice point(SGLP) sets. Moreover, we provide efficient approaches for identifying the(nearly)optimal SGLP sets under a given criterion. Combining the linear level permutation technique, we obtain a class of asymptotically optimal SLhDs in invariant spaces, where the L1-distance in each stage is either optimal or asymptotically optimal. Numerical results demonstrate that the SGLP set has a better space-filling property than the existing SLhDs in invariant spaces. It is also shown that SGLP sets have less computational complexity and more adaptability.

关键词： contracting space maximin distance nested Latin hypercube design sequential design space-fillingdesign

Magnetic Topological Dirac Semimetal Transition Driven by SOC in EuMg_(2)Bi_(2)

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Chinese Physics Letters 2024年第1期41卷 63-67页

作者：王佳萌钱浩吉姜琦乔山叶茂 State Key Laboratory of Functional Materials for Informatics Shanghai Institute of Microsystem and Information TechnologyChinese Academy of SciencesShanghai 200050China Center of Materials Science and Optoelectronics Engineering University of Chinese Academy of SciencesBeijing 100049China Research Center for Intelligent Chips and Devices Zhejiang LabHangzhou 311121China Center for Transformative Science ShanghaiTech UniversityShanghai 201210China School of Physical Science and Technology ShanghaiTech UniversityShanghai 201210China Shanghai Synchrotron Radiation Facility Shanghai Advanced Research InstituteChinese Academy of SciencesShanghai 201204China

Magnetic topological semimetals have been at the forefront of condensed matter physics due to their ability to exhibit exotic transport *** the interplay between magnetic and topological orders in systems with broken time-reversal symmetry is crucial for realizing non-trivial quantum *** delve into the electronic structure of the rare-earth-based antiferromagnetic Dirac semimetal EuMg_(2)Bi_(2) using first-principles calculations and angle-resolved photoemission *** calculations reveal that the spin-orbit coupling(SOC)in EuMg_(2)Bi_(2) prompts an insulator to topological semimetal transition,with the Dirac bands protected by crystal *** linearly dispersive states near the Fermi level,primarily originating from Bi 6p orbitals,are observed on both the(001)and(100)surfaces,confirming that EuMg_(2)Bi_(2) is a three-dimensional topological Dirac *** research offers pivotal insights into the interplay between magnetism,SOC and topological phase transitions in spintronics applications.

关键词： spectroscopy topological Dirac