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Accurate electron affinity of atomic cerium and excited states of its anion

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Chinese Physics B 2020年第7期29卷 275-280页

作者： Xiao-Xi Fu Ru-Lin Tang Yu-Zhu Lu Chuan-Gang Ning Department of Physics State Key Laboratory of Low-Dimensional Quantum PhysicsTsinghua UniversityBeijing 100084China Collaborative Innovation Center of Quantum Matter Beijing 100084China

electron affinities(EA)of most lanthanide elements still remain unknown owing to their relatively lower EA values and the fairly complicated electronic *** the present work,we report the high-resolution photoelectron spectra of atomic cerium anion Ce−using the slow electron velocity-map imaging method in combination with a cold ion *** electron affinity of Ce is determined to be 4840.62(21)cm^-1 or 0.600160(26)***,several excited states of Ce(^4H9/2,^4I9/2,^2H9/2,^2G9/2,^2G7/2,^4H13/2,^2F5/2,and ^4I13/2)are observed.

关键词： electron affinity cerium anion slow electron velocity-map imaging cold ion trap

Observation of positive and small electron affinity of Si-doped AlN films grown by metalorganic chemical vapor deposition on n-type 6H–SiC

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Chinese Physics B 2016年第5期25卷 369-372页

作者：梁锋陈平赵德刚江德生赵志娟刘宗顺朱建军杨静刘炜何晓光李晓静李翔刘双韬杨辉张立群刘建平张源涛杜国同 State Key Laboratory on Integrated Optoelectronics Institute of Semiconductors Chinese Academy of Sciences Center for Physicochemical Analysis and Measurement Institute of Chemistry Chinese Academy of Sciences Suzhou Institute of Nano-tech and Nano-bionics Chinese Academy of Sciences State Key Laboratory on Integrated Optoelectronics College of Electronic Science and Engineering Jilin University

We have investigated the electron affinity of Si-doped AlN films（N_（Si）= 1.0 × 10^（18）–1.0 × 10_（19）cm^（-3）） with thicknesses of 50, 200, and 400 nm, synthesized by metalorganic chemical vapor deposition（MOCVD） under low pressure on the ntype（001）6H–SiC substrates. The positive and small electron affinity of AlN films was observed through the ultraviolet photoelectron spectroscopy（UPS） analysis, where an increase in electron affinity appears with the thickness of AlN films increasing, i.e., 0.36 eV for the 50-nm-thick one, 0.58 eV for the 200-nm-thick one, and 0.97 e V for the 400-nm-thick *** the x-ray photoelectron spectroscopy（XPS） analysis on the surface contaminations, it suggests that the difference of electron affinity between our three samples may result from the discrepancy of surface impurity contaminations.

关键词： AlN electron affinity photoelectron spectroscopy metalorganic chemical vapor deposition

Work Function and electron affinity of Semiconductors:Doping Effect and Complication due to Fermi Level Pinning

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Energy & Environmental Materials 2021年第3期4卷 273-276页

作者： Guosheng Shao State Center for International Cooperation on Designer Low-carbon and Environmental Materials Zhengzhou UniversityZhengzhou 450001China School of Materials Science and Engineering Zhengzhou UniversityZhengzhou 450001China Zhengzhou Materials Genome Institute XingyangZhengzhou 450100China

Semiconductors are a major category of functional materials essential to various applications to sustain the modern *** applied materials or devices utilizing semiconductors are enabled by interfaces or junctions,such as solar cells,electronic/photonic devices,environmental sensors,and redox ***,the author provides a critical commentary on photoemission measurement of the work function and,more importantly,the electron affinity of semiconductors essential for energy band diagram of *** effort is made towards addressing complications associated with Fermi level pinning due to surficial states of doped semiconductors.

关键词： band edges electron affinity Fermi pinning ultraviolet photoelectron spectroscopy work function

Measurement of electron affinity of Atomic Lutetium via the Cryo-SEVI Method

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Chinese Journal of Chemical Physics 2019年第2期32卷 187-192,I0002页

作者： Xiao-xi Fu Ru-lin Tang Yu-zhu Lu Chuan-gang Ning Department of Physics State Key Laboratory of Low-Dimensional Quantum Physics Tsinghua University Beijing 10084 China Collaborative Innovation Center of Quantum Matter Beijing 100084 China

electron affinities (EAs) of most lanthanide elements still remain unknown due to their relatively low EA values. In the present work, the cryogenically controlled ion trap is used for accumulating atomic lutetium anion Lu^-, which makes the measurement of electron affinity of lutetium become practicable. The high-resolution photoelectron spectra of Lu^- are obtained via the slow-electron velocity-map imaging method. The electron affinity of Lu is determined to be 1926.2(50) cm^-1 or 0.23882(62) eV. In addition, two excited states of Lu^- are observed.

关键词： electron affinity Cryogenically controlled ion trap Lutetium anion

Energy level engineering of charge selective contact and halide perovskite by modulating band offset:Mechanistic insights

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Journal of Energy Chemistry 2021年第3期30卷 822-829页

作者： Yassine Raoui Hamid Ez-Zahraouy Samrana Kazim Shahzada Ahmad BCMaterials Basque Center for MaterialsApplications and NanostructuresBld.Martina CasianoUPV/EHU Science ParkBarrio Sarriena s/n48940 LeioaSpain IKERBASQUE Basque Foundation for ScienceBilbao 48013Spain Laboratory of Condensed Matter and Interdisciplinary Sciences Faculty of SciencesMohammed V UniversityRabatMorocco

Mixed cation and anion based perovskites solar cells exhibited enhanced stability under outdoor conditions,however,it yielded limited power conversion efficiency when TiO_(2) and Spiro-OMeTAD were employed as electron and hole transport layer(ETL/HTL)*** inevitable interfacial recombination of charge carriers at ETL/perovskite and perovskite/HTL interface diminished the efficiency in planar(n-i-p)perovskite solar *** employing computational approach for uni-dimensional device simulator,the effect of band offset on charge recombination at both interfaces was *** noted that it acquired cliff structure when the conduction band minimum of the ETL was lower than that of the perovskite,and thus maximized interfacial ***,if the conduction band minimum of ETL is higher than perovskite,a spike structure is formed,which improve the performance of solar *** optimum value of conduction band offset allows to reach performance of 25.21%,with an open circuit voltage(VOC)of 1231 mV,a current density JSC of 24.57 mA/cm^(2) and a fill factor of 83.28%.Additionally,we found that beyond the optimum offset value,large spike structure could decrease the *** an optimized energy level of Spiro-OMeTAD and the thickness of mixed-perovskite layer performance of 26.56% can be *** results demonstrate a detailed understanding about the energy level tuning between the charge selective layers and perovskite and how the improvement in PV performance can be achieved by adjusting the energy level offset.

关键词： Device modelling electron affinity Conduction band offset Valence band offset Charge recombination Perovskite solar cell

Study of Structures and electronic Properties of Pd_(n–1)Pb and Pd_n (n≤8) Clusters

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Chinese Journal of Structural Chemistry 2007年第9期26卷 1092-1096页

作者：方芳朱瑜赵倩蒋刚王红艳 School of Information Engineering Hubei Institute for Nationalities Institute of Atom and Molecular Physics Sichuan University Chengdu 610065 China School of Physics Hubei Institute for Nationalities School of Physical Science and Technology Southwest University Institute of Atom and Molecular Physics Sichuan University

Geometric and electronic properties of Pdn–1Pb and Pdn （n≤8） clusters have been studied by using density functional theory with effective core potentials, focusing on the differences between mono- and bimetallic clusters. The average bond length of Pdn–1Pb （n≤8） bimetallic clusters is longer than that of pure palladium clusters except for n = 2 and 3. The most stable structure of Pdn–1Pb （n≤7） is the singlet where there is at least a Pd or Pb atom on its excited state. The energy gaps of Pd–Pb binary clusters are narrower than those of Pdn clusters, and then the chemical activity is strengthened when Pdn clusters are doped with Pb.

关键词： Pd-Pb bimetallic clusters equilibrium geometries,bonding energy electron affinity Ionization potential HOMO-LUMO gap

Formula for average energy required to produce a secondary electron in an insulator

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Chinese Physics B 2013年第5期22卷 540-542页

作者：谢爱根詹煜高志勇吴红艳 School of Physics and Optoelectronic Engineering Nanjing University of Information Science and Technology

Based on a simple classical model specifying that the primary electrons interact with the electrons of a lattice through the Coulomb force and a conclusion that the lattice scattering can be ignored, the formula for the average energy required to produce a secondary electron （ε） is obtained. On the basis of the energy band of an insulator and the formula for e, the formula for the average energy required to produce a secondary electron in an insulator （εi） is deduced as a function of the width of the forbidden band （Eg） and electron affinity X. Experimental values and the εi values calculated with the formula are compared, and the results validate the theory that explains the relationships among Eg, X, and ei and suggest that the formula for εi is universal on the condition that the primary electrons at any energy hit the insulator.

关键词： width of forbidden band electron affinity average energy insulator

Adsorption behaviors of gas molecules on the surface of ZnO nanocrystals under UV irradiation

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Science China(Technological Sciences) 2019年第12期62卷 2226-2235页

作者： ZHANG QiuPing XIE GuangZhong DU HongFei YANG Jing SU YuanJie TAI HuiLing XU Ming ZHAO Kang State Key Laboratory of electronic Thin Films and Integrated Devices School of Optoelectronic Science and EngineeringUniversity of Electronic Science and Technology of China(UESTC)Chengdu 610054China Key Laboratory of Information Materials of Sichuan Province School of Elctrical and Information EngineeringSouuhwest University for NationalitiesChengdu 610041China

A UV-activated room temperature chemiresistive gas sensor based on ZnO nanocrystals film was fabricated. Its gas sensing properties under various conditions were also investigated in detail. The results shed new insight into the adsorption behaviors of gas molecules on the surface of ZnO nanocrystals under UV irradiation. The chemisorbed oxygen species(O^-2(ads)(hv)) induced by UV light govern the adsorption and desorption ways of other gas molecules on the surface of ZnO nanocrystals, which is dependent on the electron affinity of gas molecules. Gas molecules with higher electron affinity than oxygen molecules can be adsorbed on the surface by the competitive adsorption way, extracting electrons from the surface. Gas molecules with lower electron affinity than oxygen molecules are attracted by the adsorbed O^-2(ads)(hv)layer, releasing electrons to the surface. These processes can influence the gas sensing properties of the sensor. Our findings will pave the way for the fundamental understanding and design of UV-activated gas sensor in the future.

关键词： adsorption behaviors electron affinity UV-activated gas sensor ZnO nanocrystals

Theoretical Studies on Structures and electron Affinities of 5-and 6-Halouracils

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Chemical Research in Chinese Universities 2009年第3期25卷 388-396页

作者： WANG Hui-ping XU Wen-guo ZHANG Hong-xing State Key Laboratory of Theoretical Chemistry Institute of Theoretical Chemistry Jilin University Changchun 130021 P R. China Institute for Chemical Physics Beijing Institute of Technology Beijing 100081 P. R. China

The molecular structures and electron affinities of 5- and 6-halouracils（XU, X=F, Cl, Br） were determined by means of five different density functional methods. The basis set used in this work is of double-（plus polariza- tion（DZP） quality with additional diffuse s- and p-type functions, denoted DZP＋＋. The geometries were fully optimized with each density functional theory（DFT） method, and discussed. Three different types of the neutral-anion energy separations reported in this work are the adiabatic electron affinity（AEA）, the vertical electron affinity（VEA）, and the vertical detachment energy（VDE）. An excellent agreement between our B3LYP results and those obtained by other calculations regarding the structural modifications and electron affinities of neutral and anion 5XU was found. The differences in charge distribution between uracil and halogenated uracils were indicated, thus the ability to form the hydrogen bonds of halogenated uracils was discussed. It shows the applicability of the DFT/DZP＋＋ method to predict the similar molecular models at a highly economical computational cost.

关键词： electron affinity Vertical electron affinity Vertical detachment energy Halouracil Charge distribution