Yi Zhang

University of Science and Technology of China, Luchow, Anhui Sheng, China

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Publications (15)25.19 Total impact

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    ABSTRACT: A toroidal charge exchange recombination spectroscopy (CXRS) diagnostic, on the basis of a heating neutral beam injector (NBI), is constructed on EAST tokamak. Simulation of Spectra (SOS) code is used to design and evaluate the diagnostic performance. 30 spatial channels work simultaneously in recent experiment, which covers a radial region from 1.55 m to 2.30 m in the cross section. The CXRS has a radial resolution of 1–3.5 cm from core to edge. The acquisition time is typically 10 ms, limited by the poor photon statistics. The diagnostic can observe not only the normal C5+ emission line at 529.1 nm but also any interested wavelength in the range of 400–700 nm. In this work, a brief overview on the R&D and the instrument performance for the toroidal CXRS diagnostic is described, together with first results.
    Fusion Engineering and Design 04/2015; DOI:10.1016/j.fusengdes.2015.02.063 · 1.15 Impact Factor
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    ABSTRACT: In numerous reports on selective solid-phase extraction (SPE) of uranium, the extraction of uranium is generally accepted as a direct coordination of the ligands on solid matrix with the uranyl, in which the critical effect of the hydration shell on the uranyl is neglected. The related mechanism in the extraction process remains unclear. Herein, the detailed calculation of activation energy and the geometry of the identified transition states reveal that the uranium extraction by a newly-synthesized urea-functionalized graphite oxide (Urea-GO) is in essence an exchange process between the ligands on Urea-GO and the coordinated water molecules in the first hydration shell of the uranyl. Moreover, we demonstrate that it is the ketone oxygen in the urea ligand to displace the coordinated water molecule of uranyl due to its stronger bonding ability and lower steric-hindrance, whereas the nitrogen atoms in the same ligand is proved to be an electron donor that enables the oxygen atom to have stronger affinity for uranium through electron delocalization effects evaluated on the basis of calculations of the second-order interaction energy between donor and acceptor orbitals. We therefore propose a new ligand-exchange mechanism for the SPE process. This study advance fundamental understanding of uranium extraction, and provide theoretical and practical guidance on ligand design for selective complexation of uranium(VI) and other metal ions in aqueous solution. Finally, the effect of nitrate ion on the extraction of uranyl was successfully explained based on the experimental and theoretical study.
    Physical Chemistry Chemical Physics 02/2015; 17(11). DOI:10.1039/C4CP05508J · 4.20 Impact Factor
  • The European Physical Journal D 01/2015; 69(1). DOI:10.1140/epjd/e2014-50639-7 · 1.40 Impact Factor
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    ABSTRACT: The figure shows the rovibrational interaction energies ευJint for the state a3∑u+ of 7Li27Li2 molecule, and indicates that the absolute values of rovibrational interactions are getting greater as either vibrational state υ or rotational state J increases. The fact that all interaction energies ευJint are negative confirms that the rovibrational interaction energies are attractive, and that it is the rovibrational coupling makes the rovibrational energy EυJEυJ smaller than the sum Eυ+JEυ+J of its corresponding vibrational energy ευευ and the rotational energy εJεJ and makes the rovibrational system stable
    Spectrochimica Acta Part A Molecular and Biomolecular Spectroscopy 11/2014; 132:32–37. DOI:10.1016/j.saa.2014.04.137 · 2.13 Impact Factor
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    ABSTRACT: The analytical potential energy functions have been calculated for the ground state X 1Σ+g and four excited electronic states a 1Πg , a 3Σ+u , B′3Σ−u and B 3Πg of N2 molecule using the algebraic and energy-consistent methods (AM-ECM). Based on our previously published full AM vibrational energies and spectroscopic constants, the low-lying force constants fn, the expansion coefficients an and the variational parameters λ in the AM–ECM potentials are determined for these states. The computed AM–ECM potential energy curve of each state is in excellent agreement with the experimental data and better than other analytical potentials.
    Molecular Physics 10/2014; 112(20). DOI:10.1080/00268976.2014.904052 · 1.64 Impact Factor
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    ABSTRACT: Solid polymer thermal decomposition involves complex physical and chemical processes that are closely related to the microscopic molecular information (chemical structure, physical configuration, etc.). However, some important molecular information such as molecular weight is seldom involved in previous solid thermal decomposition studies due to the complexity of solid polymer itself. This work proposes a kinetic equation to study solid polymer thermal decomposition in which the influence of molecular weight to the decomposition is included based on an independent identical particle (IIP) model. Applications of this equation to the thermal decomposition of solid poly-α-methyl styrene (PαMS) show that: 1) there is good agreement between experimental and theoretical thermal decomposition rates; 2) molecular weight can affect not only the activation energy but also the pre-exponential factor of the thermal decomposition kinetic equation; 3) the higher the molecular weight is, the faster the PαMS decomposes in the main decomposition temperature range.
    Polymer Degradation and Stability 10/2014; 110. DOI:10.1016/j.polymdegradstab.2014.10.002 · 2.63 Impact Factor
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    ABSTRACT: The impacts of diffuse orbitals to the correlation/polarization potentials, and hence to the vibrational scattering cross sections, are investigated in this study. We compute the BTAD (better than adiabatic) and DSG (distributed spherical Gaussian) potentials based on the Dunning basis from cc-pVDZ to aug-cc-pV6Z, and apply them to the vibrational scattering of an e–N2 molecule. The results show that the diffuse functions are important for scattering and that the frequently used basis of size up to cc-pVTZ is not sufficient. The correlation-consistent aug-cc-pVXZ series, which include s, p, d, f, g, h, and i Gaussian orbitals, apparently affect the correlation/polarization potentials and, hence, could give the cross sections on the Hartree–Fock limit. Furthermore, in the process of reaching the Hartree–Fock limit by enlarging the basis, the differential cross sections may oscillate, which makes the Hartree–Fock limit very important in testing different theoretical models.
    Journal of Physics B Atomic Molecular and Optical Physics 10/2014; 47(19). DOI:10.1088/0953-4075/47/19/195203 · 1.92 Impact Factor
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    ABSTRACT: Thermal decomposition is caused by the breaking of the bonds of polymer chains after they are stretched to a length threshold. Any factors that affect the bond stretch can affect the thermal decomposition process. The physical processes like glass-transition changes and the physical configuration of the polymer chains affect the stretch mechanism apparently. Thus, glass-transition and molecular weight may be reflected in the thermal decomposition process characterized by the thermogravimetric (TG) or differential thermogravimetric (DTG) curves. This idea was confirmed by the thermal decomposition of solid poly-alpha-methyl styrene (P alpha MS). The experiment results showed that the DTG curves change suddenly near the glass-transition temperature, and the activation energy goes up with an increase of molecular weight, which indicates that the physical process is vital in the thermal decomposition process.
    08/2014; 62:012020. DOI:10.1088/1757-899X/62/1/012020
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    ABSTRACT: Based on the algebraic method (AM) and the energy consistent method (ECM), an AM-ECM protocol for analytical potential energy curves of stable diatomic electronic states is proposed as functions of the internuclear distance. Applications of the AM-ECM to the 6 hydride electronic states of HF-X1Σ+, DF-X1Σ+, D35Cl-X1Σ+, 6LiH-X1Σ+, 7LiH-X1Σ+, and 7LiD-X1Σ+ show that the AM-ECM potentials are in excellent agreement with the experimental RKR data and the full AM-RKR data, and that the AM-ECM can obtain reliable analytical potential energies in the molecular asymptotic and dissociation region for these molecular electronic states.
    The European Physical Journal D 12/2013; 68(1). DOI:10.1140/epjd/e2013-40437-2 · 1.40 Impact Factor
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    ABSTRACT: The algebraic method (AM) proposed by Sun et al. is improved to be a variational AM (VAM) to offset the possible experimental errors and to adapt to the individual energy expansion nature of different molecular systems. The VAM is used to study the full vibrational spectra {Eυ} and the dissociation energies De of (4)HeH(+)-X(1)Σ(+), (7)Li2-1(3)Δg,Na2-C(1)Πu,NaK-7(1)Π, Cs2-B(1)Πu and (79)Br2-β1g((3)P2) diatomic electronic states. The results not only precisely reproduce all known experimental vibrational energies, but also predict correct dissociation energies and all unknown high-lying levels that may not be given by the original AM or other numerical methods or experimental methods. The analyses and the skill suggested here might be useful for other numerical simulations and theoretical fittings using known data that may carry inevitable errors.
    Spectrochimica Acta Part A Molecular and Biomolecular Spectroscopy 08/2013; 117C:442-448. DOI:10.1016/j.saa.2013.08.043 · 2.13 Impact Factor
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    ABSTRACT: Although all of the neutral alkaline earth dimers have been studied experimentally, only for the beryllium and strontium systems have the diatomic radical cations been subjected to modern spectroscopic techniques. In the present research, both coupled cluster and full configuration interaction methods were used to describe the M2+ systems. Basis sets as large as aug-cc-pCV5Z were chosen. For both Be2+ and Sr2+ agreement with the experiments is outstanding. Final predictions for the unknown dissociation energies are 10,651 (Mg2+), 9605 (Ca2+), and 8980 cm−1 (Ba2+). The M2+ dissociation energies decrease monotonically going down the periodic except for the Sr2+ - Ba2+ pair. The unknown bond distances re are 3.015 (Mg2+), 3.814 (Ca2+), 4.194 (Sr2+), and 4.587 Å (Ba2+).
    Molecular Physics 08/2013; 111(14-15). DOI:10.1080/00268976.2013.802818 · 1.64 Impact Factor
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    ABSTRACT: Since the order in the diatomic potential (or vibrational energy) expansion may be different from state to state, the algebraic method (AM) proposed by Sun et al. (J Mol Spectrosc 2002; 215: 93–105) is modified to adapt to the individual nature of different energy expansions by changing an original fixed order to a flexible one. The modified AM with a flexible order can be used to deal with the possible “butterfly effect” that may happen in spectroscopic computations, and it is applied to study the full vibrational spectra {Eυ}{Eυ} and the dissociation energies De for L7i2−23Σg+, K2−13ΠgK2−31Πg, Cs2−33∑g+, KLi−X1∑+, and RbCs−1X+ΣRbCs−X1Σ+ electronic states. The results not only reproduce the known experimental vibrational energies, but also correctly predict the dissociation energies and all unknown energies that have not been obtained for these electronic states using the original AM. These facts demonstrate that the modified AM are good for many more diatomic systems by using the proper order of each corresponding diatomic state.
    Journal of Quantitative Spectroscopy and Radiative Transfer 05/2013; 120:81–89. DOI:10.1016/j.jqsrt.2013.02.018 · 2.29 Impact Factor
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    ABSTRACT: An analytical formula was proposed recently to predict the accurate P-branch spectral lines of rovibrational transitions for diatomic systems by taking multiple spectral differences. A similar analytical expression was suggested here to predict the Q-branch spectral lines of rovibrational transitions. This formula was applied to study the high-lying Q-branch emission spectra of the (4,1) and (3,1) bands of the A 1Π - X1 Σ+ system of IrN molecule using fifteen known accurate experimental transition data. The results show that not only the known experimental transition lines were reproduced but also the correct values of the unknown spectral lines were predicted.
    Guang pu xue yu guang pu fen xi = Guang pu 04/2012; 32(4):865-70. DOI:10.3964/j.issn.1000-0593(2012)04-0865-06 · 0.27 Impact Factor
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    ABSTRACT: An analytical formula is suggested to predict the accurate Q-branch spectral lines of rovibrational transitions for diatomic systems by taking multiple spectral differences, and is applied to study the high-lying Q-branch emission spectra of the (0, 0) band of the ⁴Γ₅/₂-⁴Φ₃/₂ and ⁴Γ₇/₂ -⁴Φ₅/₂ systems of TiF molecule using fifteen known accurate experimental transition data. The results show that not only the known experimental transition lines are accurately reproduced, but also the correct values of the unknown spectral lines are predicted.
    Spectrochimica Acta Part A Molecular and Biomolecular Spectroscopy 02/2012; 91:244-7. DOI:10.1016/j.saa.2012.01.076 · 2.13 Impact Factor
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    ABSTRACT: The fixed order in the algebraic method (AM) suggested by Sun et al. is changed to be a flexible one in the vibrational energy expansion because the order of diatomic potential energy expansion may not be a constant. The AM with a flexible order was used to tackle the possible "butterfly effect" that may be encountered in spectroscopic computations, and to study the full vibrational levels {E(v)} and the dissociation energies D(e) for N2 - a'(1) sigma(u)(-), Li2(+) - 2 2sigma(g)(+), 4HeD(+) - X 1sigma(-) and 39K 85Rb- (2) 3sigma(+) electronic systems. The results reproduced all known experimental vibrational energies, and predicted correct dissociation energies and all unknown high-lying levels that may not be given if one uses original AM. The calculations showed that the modified AM can be extended to study the full vibrational spectra for many more diatomic systems.
    Guang pu xue yu guang pu fen xi = Guang pu 01/2012; 32(1):15-9. DOI:10.3964/j.issn.1000-0593(2012)01-0015-05 · 0.27 Impact Factor

Publication Stats

5 Citations
25.19 Total Impact Points

Institutions

  • 2015
    • University of Science and Technology of China
      • School of Nuclear Science and Technology
      Luchow, Anhui Sheng, China
  • 2013–2014
    • Xihua University
      • School of Physics and Chemistry
      Hua-yang, Sichuan, China
  • 2012–2014
    • Sichuan University
      • • College of Physical Science and Technology
      • • Institute of Atomic and Molecular Physics
      • • Department of Physics
      Hua-yang, Sichuan, China