Interpretation of the Experimental Electron Momentum Spectra of 5e1/2 and 5e3/2 Orbitals of CF3I with Relativistic Calculations

With our newly developed method, we calculate the spin-orbit splitting states 5e1/2 and 5e3/2 of the CF3I molecule incorporating the relativistic effects. Our theoretical results agree excellently with the recent experimental observations. The present study shows that relativistic effects can evidently change the electron momentum distributions of molecular orbitals when a medium Z element is included, such as iodine.     

Measurement of the KLL Dielectronic Recombination Resonances in He-like to C-like Kr Ions

The KLL dielectronic recombination processes of highly charged He-like to C-like Kr ions have been studied experimentally. The measurement was performed on the newly developed Shanghai electron beam ion trap （Shanghai-EBIT） facility. Characteristic x-rays from both dielectronic recombination and radiative recombination are detected as the electron beam energy is scanned through the resonances. The KLL resonant strengths obtained are 5.41×10^-19, 4.33×10^-19, 3.59×10^-19, 2.05×10^-19 and 0.98×10^-19 cm^2 eV for He-like to C-like Kr ions, respectively.     

Dielectronic Recombination of Sn^10＋ Ions and Related Satellite Spectra

Based on the multi-configuration Dirac-Fock method, theoretical calculations are carried out for the dielectronic recombination （DR） rate coefficients and the collision excitation rate coefficients of Sn^10＋ ions. It is found that the total DR rate coefficient has its maximum value between 10eV and 100eV and is greater than either the radiative recombination or three-body recombination rate coefficients （the number of free electrons per unit is 10^21 cm^3） for the ease of Te 〉 1 eV. Therefore, DR can strongly influence the ionization balance of laser produced multi-charged tin ions. The related dieleetronie satellite cannot be ignored at low temperature Te 〈 5 eV.     

Theoretical Study on Inner Shell Electron Impact Excitation of Lithium

Cross sections for electron impact excitation of lithium from the ground state 1s^22s to the excited states 1s2s^2, 1s2p^2, 1s2snp （n = 2-5）, 1s2sns （n = 3 5）, 1s2pns （n = 3-5）, and 1s2pnp （n = 3-5） are calculated by using a full relativistic distorted wave method. The latest experimental electron energy loss spectra for inner-shell electron excitations of lithium at a given incident electron energy of 2500 eV [Chin. Phys. Lett. 25 （2008）3649] have been reproduced by the present theoretical investigation excellently. At the same time, the structures of electron energy loss spectra of lithium at low incident electron energy are also predicted theoretically, it is found that the electron energy loss spectra in the energy region of 55-57eV show two-peak structures.     

Relativistic Energies and Auger Widths of High-Lying Doubly-Excited States 1s^23lnl′ ^1De in Be-Like O^4＋ Ions

The saddle-point variational method and restricted variational method are used to calculate energies of doublyexcited singlet states 1s^23lnl′ （n =3-.） ^1 De in Be-like O^4＋ ions, including the mass polarization and relativistic corrections. The saddle-point complex-rotation method is used to compute the Auger widths and Auger transition rates. These results are compared with other theoretical and experimental data in the literature.     

KLn Dielectronic Recombination Process of B- Through He-like Cu Ions

The KLn dielectronic recombination processes of trapped highly charged B-like through He-like Cu ions are studied theoretically, and the theoretical results are used to analyse our previous experimental data at Heidelberg electron beam ion trap （EBIT）. The theoretical resonant positions agree with the experimental resonant positions to a precision of 0.4%, in comparison with the resonant positions of those highest peaks between theory and experiment. The experimental spectra are then fitted using a formula with the theoretical resonant energies and strengths, the result shows good overall agreement between theory and experiment over a wide electron energy range. The distribution of highly charged states is obtained from the fitting parameters.     

红宝石能谱的理论研究

 本文用限制Hartree-Fock自洽场方法对红宝石进行了计算，得到了单电子分子轨道，在此基础上利用不可约张量方法求解红宝石价电子体系多体Schrodinger方程，得到了与实验相符的红宝石d－d跃迁能谱，标准误差为九百波数。进一步计算了在不同压力下红宝石d－d跃迁能谱。结果表明，能谱中R₁线（⁴A₁→²E）随压力增大产生红移，与实验定性一致。     

Theoretical Study of Interesting Fine-Structure Splittings for 23P0, 1, 2 States along Helium Isoelectronic Sequence

Using the multi-configuration Dirac Fock method including the Breit interactions and QED corrections, we calculate the fine-structure energy levels of the 2^3 Po, 1,2 states along the helium isoelectronic sequence with atomic number up to Z = 36, where LS-coupling is appropriate. Our calculation results agree with the experimental results within about 1%. We elucidate the mechanism of the interesting fine-structure splittings for the 2^3Po,1,2 states along the helium isoelectronic sequence, i.e. the competitions between the spin-orbit interactions and the Breit interactions which represent the relativistic retardation effect of electromagnetic interactions.     

ANALYSIS OF THE E2 TRANSITIONS BETWEEN THE d+a CLUSTER STATES OF 6Li WITH THE RGM

The E2 reduced transition probabilities between the d-a cluster states of ⁶Li were calculated by the RGM in this paper.The resulting B(E2;E₁→E₀)=21.06fm⁴ consistented with the experimental value 25.1±2.0fm⁴ more than the calculated values of the double-well cluster model including p-state exciting and LCCO.Also,the B(E2;E₃→E₀)=9.67fm⁴ coincided with the exprimental value 6.483±3.360fm⁴ within the error range.     

Additivity Rule for Electron-Molecule Total Cross Section Calculations at 50-5000 eV： A Geometrical Approach

To quantify the changes of the geometric shielding effect in a molecule as the incident electron energy varies, we present an empirical fraction, which represents the total cross section （TCS） contributions of shielded atoms in a molecule at different energies. Using this empirical fraction, a new formulation of the additivity rule is proposed. Using this new additivity rule, the TCSs for electron scattering by CO2, C2H2, C6H12 （cyclo-hexane） and CsH16 （cyclo-octane） are calculated in the range 50-5000 e V. Here the atomic cross sections are derived from the experimental TCS results of simple molecules （H2, O2, CO）. The quantitative TCSs are compared with those obtained by experiments and other theories, and good agreement is attained over a wide energy range.     

High-Temperature Characteristics of Ti/Al/Ni/Au Ohmic Contacts to n-GaN

We present the high-temperature characteristics of Ti/Al/Ni/Au（15 nm/220 nm/40 nm/50 nm） multiplayer contacts to n-type GaN （Nd = 3.7 × 10^17 cm^-3, Nd = 3.0 × 10^18 cm^-3）. The contact resistivity increases with the measurement temperature. Furthermore, the increasing tendency is related to doping concentration. The higher the doped, the slower the contact resistivity with decreasing measurement temperature. Ti/Al/Ni/Au ohmic contact to heavy doping n-GaN takes on better high temperature reliability. According to the analyses of XRD and AES for the n-GaN/Ti/Al/Ni/Au, the Au atoms permeate through the Ni layer which is not thick enough into the AI layer even the Ti layer.     

Inner Shell Excitations of Lithium Studied by Fast Electron Impact

Electron energy loss spectra for the inner shell excitations of atomic lithium are measured at an incident electron energy of 2500eV and scattering angles of 0^o, 2^o, 4^o and 6^o. Two optically forbidden transitions of （ls2s^2）^2S and （ ls2s ^3 S）3s^2 S are observed. The generalized oscillator strength ratios for ls（2s2p^3 P）2 P^0 to 1s（ 2s2p^1 P）2 P^0 were determined, and they are independent of the momentum transfer.     

Artificial Modulation of Ferroelectric Thin Films into Antiferroelectric through H+ Implantation for High-Density Charge Storage

Hydrogen ions are implanted into Pb（Zro.3Tio.7）03 1014 ions/cm^2. Pseudo-antiferroelectric behaviour in thin films at the energy of 40keV with a flux of 5 x the implanted thin films is observed, as confirmed by the measurements of polarization versus electric hysteresis loops and capacitance versus voltage curves. X-ray diffrac- tion patterns show the film structures before and after H＋ implantation both to be perovskite of a tetragonal symmetry. These findings indicate that hydrogen ions exist as stable dopants within the films. It is believed that the dopants change domain-switching behaviour via the boundary charge compensation. Meanwhile, time dependence of leakage current density after time longer than lOs indicates the enhancement of the leakage cur- rent nearly in one order for the implanted film, but the current at time shorter than i s is mostly the same as that of the original film without the ionic implantation. The artificial tailoring of the antiferroelectric behaviour through H＋ implantation in ferroelectric thin films is finally proven to be achievable for the device application of high-density charge storage.     

Theoretical calculation of the isoelectronic line ratio of Li-like Ti and Cr under different mixture ratios

With the consideration of coronal conditions, a simplified model and the steady-state rate-equation are used to calculate the isoelectronic line ratio for transition in Li-like Ti and Cr from the electron temperature 400 to . The relation between the isoelectronic line ratio and the electron temperature are provided under different mixture ratios of Ti and Cr. Then, the mixture ratio from 2:1 to 3:1 between Ti and Cr are obtained that are suitable for the electron temperature diagnostic by using isoelectronic line ratio of Li-like Ti and Cr. The relative abundance of two close ionization stages, which is from bare nucleus to Be-like ionization stage, are given and show that the He-, Li- and Be-like are the principal ionization stages from 400 to for Ti and from 500 to for Cr. The Li-like charge state will reach the maximum distribution approximately from 400 to for Ti and from 547 to for Cr. The paper also shows that the dielectronic recombination and spontaneous radiative recombination rates only have small effects on the isoelectronic line ratio in the electron temperature 400-.     

Quantitative ferroelectric characterization of single submicron grains in Bi-layered perovskite thin films

The local polarization state and the electromechanical properties of ferroelectric thin films can be probed via the converse piezoelectric effect using scanning force microscopy (SFM) combined with a lock-in technique. This method, denominated as piezoresponse SFM, was used to characterize at the nanoscale level ferroelectric SrBi₂Ta₂O₉ and Bi₄Ti₃O₁₂ thin films, grown by pulsed laser deposition. Two types of samples were studied: polycrystalline films, with grains having random orientations, and epitaxial films, consisting of (100)_orth- or (110)_orth-oriented crystallites, 100 nm to 2 7m in lateral size, which are embedded into a (001)-oriented matrix. The ferroelectric domain structure was imaged and the piezoelectric response under different external conditions was locally measured for each type of sample. Different investigation procedures are described in order to study the ferroelectric properties via the electromechanical response. A distinct ferroelectric behavior was found for single grains of SrBi₂Ta₂O₉ as small as 200 nm in lateral size, as well as for 1.2 7m쏿 nm crystallites of Bi₄Ti₃O₁₂. By probing separately the crystallites and the matrix the investigations have demonstrated at the nanoscale level that SrBi₂Ta₂O₉ has no spontaneous polarization along its crystallographic c-axis, whereas Bi₄Ti₃O₁₂ exhibits a piezoelectric behavior along both the a- and c-directions. The electrostriction coefficients were estimated to be 3᎒^-2 m⁴/C² for polycrystalline SrBi₂Ta₂O₉ and 7.7᎒^-3 m⁴/C² for c-orientedBi₄Ti₃O₁₂. Quantitative measurements at the nanoscale level, within the experimental errors give the same values for remanent polarization and coercive field as macroscopic ferroelectric measurements performed on the same samples.     

Electron Scattering by C4H10 and C6H6 in the Energy Range 100--1000eV

We investigate the applicability of the independent atom model （IAM） to elastic electron scattering from complex polyatomic molecules, namely C4H10 and C6H6, in the energy range 100-1000eV. The cross sections of the elastic electron scattering are calculated by employing the IAM together with the relativistic partial waves. The incorporation of both the modified absorption potential and the extended structural factor in the IAM makes the elastic differential cross sections and momentum transfer cross sections have a good agreement with the available experimental data. The present simple model seems to be insensitive to the complexity of the target molecules so that the proposed procedure can be quite useful for calculation of electron scattering from bio-molecules.     

Theoretical study of the KLL dielectronic recombination for highly charged iodine ions

With a developed program for calculation of dielectronic recombination (DR) process, which is based on multi-configuration Dirac-Fock (MCDF) method, the KLL DR processes of the highly charged helium-like to carbon-like iodine ions have been studied systematically. The contributions to doubly excited states from quantum electrodynamic (QED) and Breit effects have been discussed. The KLL DR resonant energies and corresponding resonant strengths have been calculated. The behavior of KLL resonant strengths with increasing Z are analyzed for He-like ions in particular. The theoretical DR spectra for each highly charged ion species are obtained in the KLL region. Comparison has been made between the present calculations and the latest experiments in Tokyo-EBIT.     

Chiral Lagrangian Treatment of 0^＋＋ Mesons and 0^＋＋ Glueballs

Within the framework of a nonlinear chiral Lagrangian the mass spectra and the decay properties of 0^＋＋ states below 2 GeV are studied. Assuming that f0（980）, a0（980）, K0（1430）, and f0（1500） comprise an SU（3） nonet, we make a detailed prediction about the static properties of the 0^＋＋ mesons. The substructure analysis of these states in terms of two- and four-quark components as well as a glueball component is carried out. We also consider the interaction Lagrangian and provide a preliminary study of the strong and radiative decays of the 0＋＋ mesons. The scalar glueball masses and partial widths are also presented. In view of the fact that few data of 0＋＋ mesons are clearly given in the present PDG （Particle Data Group） list and that the four-quark content of mesons is a hot issue both experimentally and theoretically, the predicted results of the paper may be helpful for upcoming experimental and theoretical studies of these mesons.     

Relativistic Distorted-Wave Calculations of Electron Impact Excitation Cross Sections of Be-Like C2＋ Ions

A fully relativistic distorted-wave program is developed based on the Grasp92 and Ratip packages to calculate electron impact excitation （EIE） cross sections. As a first application of the program, the EIE cross sections of Be-like C^α＋ ions from the metastable 1s^22s2p^3 p to 1s^22p^2 ^3 p excitation and the inner-shell excitations are calculated systematically. Meanwhile, the correlation effects of target states are discussed. It is found that the correlation effects play an important role in the low energy EIE cross sections. An excellent agreement is found when the results are compared with previous calculations and recent measurements.