Mutual recombination in slow Si^＋ ＋ H^- collisions

This paper studies the process of mutual neutralization of Si^＋ and H^- ions in slow collisions within the multichannel Landau-Zener model. All important ionic-covalent couplings in this collision system are included in the collision dynamics. The cross sections for population of specific final states of product Si atom are calculated in the CM energy range 0.05 e∨/u-5 ke∨/u. Both singlet and triplet states are considered. At collision energies below -10 e∨/u, the most populated singlet state is Si（3p4p, ^1S0）, while for energies above -150e∨/u it is the Si（3p, 4p, ^1P1） state. In the case of triplet states, the mixed 3p4p（^3S1 ＋^3P0） states are the most populated in the entire collision energy range investigated. The total cross section exhibits a broad maximum around 200 300e∨/u and for ECM ≤ 10e∨/u it monotonically increases with decreasing the collision energy, reaching a value of 8 × 10^-13 cm^2 at ECM = 0.05 e∨/u. The ion-pair formation process in Si（3p^2 ^3PJ）＋H（1s） collisions has also been considered and its cross section in the considered energy range is very small （smaller than 10^-20 cm^2 in the energy region below 1 ke∨/u）.     

Polarization Measurement of Spin-Polarized Electrons by Optical Electron Polarimeter

The polarization of spin-polarized electrons, produced from a new GaAs spin-polarized electron source, is determined by an optical electron polarimeter. The He 3^3p→2^3S1 （388.9nm） transition is used for the optical electron polarimetry. The structure and performance of the experimental setup of spin-polarized electron source and optical electron polarimeter are described. The result of polarization of 30.8% averaged spin-up and spindown polarized electrons is obtained and presented.     

Theoretical Study of Isotopic Effect of Oxygen Atom on the Stereodynamics for the O（^3P） ＋ D2 → OD ＋ D Reaction

Quasi-classical trajectory theory is used to study the isotope effect of oxygen atoms on the vector correlations in the O（^3P） ＋ D reaction at a collision energy of 25kcal/mol using accurate potential energy surface of the 3A＇ triplet state. The distributions of p（θr） and the distribution of dihedral angel p（φr） as well as p（θr,φr） are calculated. Moreover, four polarization-dependent generalized differential cross sections （PDDCSs） of product are presented in the center-of-mass frame. The results indicate that the polarization of the product presents different characters for the isotope effect of oxygen atoms. Isotopic substitute can cause obviously different effects on the four PDDCSs.     

Energy Spectrum of La3Lu2Ga3O12：Cr^3＋ and Its Pressure-Induced R-Line-Shift Reversal

By means of both the theory for pressure-induced Shifts （PS） of energy spectra and the theory for shifts of energy spectra due to electron-phonon interaction （EPI）, the normal-pressure energy spectra of α and β centers of Cr^3＋ ions for LLGG：Cr^3＋ and the PS＇s of R1 lines and U band of these centers have been calculated at 10 K, respectively. The total calculated results are in very good agreement with the experimental data. For LLGG：Cr^3＋, the pressureinduced low-high crystal-field transition and the reversal of R1-line PS take place. The pressure-dependent variation of Rmix^ei （2E - 4T2） [mixing-degree of （t2^2 （^3T1）e^4T2） and （t2^3 E） base-wavefunctions in the wavefunction of R1 state without EPI] plays a key role for the reversal of R1-line PS. The behavior of the pure electronic PS of R1 line is quite different from that of the PS of R1 line due to EPI. It is the combined effect of them that gives rise to the total PS of R1 line. The comparison between R1-line PS＇s of GSGG：Cr^3＋ and LLGG：Cr^3＋ has been made. It is found that a peak of R1-line PS appears at Rmix^ei （^2E - ^4T2） ≈ 0.08.     

Spin polarization effect for Os2 molecule

Density functional Theory （DFT） （B3p86） of Gaussian03 has been used to optimize the structure of Os2 molecule. The result shows that the ground state for Os2 molecule is 9-multiple state and its electronic configuration is ^9∑^＋g, which shows spin polarization effect of Os2 molecule of transition metal elements for the first time. Meanwhile, we have not found any spin pollution because the wavefunction of the ground state does not mingle with wavefunctions with higher energy states. So, the fact that the ground state for Os2 molecule is a 9-multiple state is indicative of spin polarization effect of Os2 molecule of transition metal elements. That is, there exist 8 parallel spin electrons. The non-conjugated electron is greatest in number. These electrons occupy different spacious tracks, so that the energy of Os2 molecule is minimized. It can be concluded that the effect of parallel spin of Os2 molecule is larger than the effect of the conjugated molecule, which is obviously related to the effect of electron d delocalization. In addition, the Murrell-Sorbie potential functions with the parameters for the ground state ^9∑^＋g and other states of Os2 molecule are derived. Dissociation energy De for the ground state of Os2 molecule is 3.3971eV, equilibrium bond length Re is 0.2403nm, vibration frequency ωe is 235.32cm^-1. Its force constants f2, f3, and f4 are 3.1032×10^2aJ·nm^-2, -14.3425×10^3aJ·nm^-3 and 50.5792×10^4aJ·nm^-4 respectively. The other spectroscopic data for the ground state of Os2 molecule ωexe, Be and ae are 0.4277cm^- 1, 0.0307cm^- 1 and 0.6491 × 10^-4cm^-1 respectively.     

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.     

Multireference configuration interaction potential curve and analytical potential energy function of the ground and low-lying excited states of CdSe

The potential energy curves （PECs） of the ground state （^3∏） and three low-lying excited states （^1∑, ^3∑,^1∏） of CdSe dimer have been studied by employing quasirelativistic effective core potentials on the basis of the complete active space self-consistent field method followed by multireference configuration interaction calculation. The four PECs are fitted to analytical potential energy functions using the Murrel-Sorbie potential function. Based on the PECs, the vibrational levels of the four states are determined by solving the Schrodinger equation of nuclear motion, and corresponding spectroscopic constants are accurately calculated. The equilibrium positions as well as the spectroscopic constants and the vibrational levels are reported. By our analysis, the ^3∏ state, of which the dissociation asymptote is Cd（^1S） ＋ Se（^3p）, is identified as a ground state of CdSe dimer, and the corresponding dissociation energy is estimated to be 0.39eV. However, the first excited state is only 1132.49cm^-1 above the ground state and the ^3∑ state is the highest in the four calculated states.     

Influence of D-state in 4He on S Factor for the 2H（d, γ）^4He Reaction

We employ a direct capture method to study the influence of D-state in ^4He on S factor for the ^2H（d,γ）^4He reaction, in which the D-state component of the colliding deuterons and D-state component in ^4He ground state are considered. The parameters of Woods-Saxon （WS） potentials are obtained by reproducing the binding energy of d-d （i.e. ^2H-^2H） system, and d-d elastic scattering phase shifts calculated by the resonating group method. The theoretical results are in good agreement with the experimental data at Ec.m〈 3 MeV. The impact of the D state probability in ^4He on the extrapolated value of the astrophysical S factor for ^2H（d, γ）^4He reaction is discussed.     

Optically Forbidden Excitations of 2s Electron of Neon Studied by Fast Electron Impact

The electron energy loss spectrum in the energy region of 42-48.5 eV of neon is measured with an angle-resolved fast-electron energy-loss spectrometer at an incident electron energy of 2500eV. Besides the dipole-allowed autoionization transitions of 2s^-1ap （n -= 3, 4） and 2p^-23s3p, the dipole-forbidden ones of 2s^-1ns （n = 3 - 6） and 2s^-13d are observed. The line profile parameters, i.e. Er, F and q for these transitions, are determined, and the momentum transfer dependence behaviour is discussed.     

Energy levels and radiative lifetimes of 3pns 3P0 and 3pnd 3P0 series of Si I

The energy levels and lifetimes of 3pns ^3po （n = 7 - 35） and 3pnd ^3p0 （n = 6 - 17） series of neutral silicon are calculated and predicted by means of multichannel quantum defect theory （MQDT）. In addition, the perturbation caused by core-excited state 3s3p^3 is discussed. The 3pnd ^3p0 series, especially 3p4d ^3p0, 3p5d ^3P0, and 3p6d ^3P0 are perturbed strongly by the core-excited state 3s3p3 ^3P0. These cause the lifetime of 3pnd ^3P0 （n = 5 - 7） to be less than that of 3p4d 3Po. The lifetimes of 3p14d ^3P0 （65479.14 cm^-1） and 3p16d ^3p0 （65608.77 cm^-1） are less than that of their frontal states respectively, because these states are perturbed by 3p22s ^3p0 （65476.48 cm-1） and 3p30s ^3p0 （65608.99 cm^-1） respectively.     

Fine structure and isotope shift of the 3s4d 3 D-3s3p 3 P, 3s5d 3 D-3s3p 3 P and 3p 2 3 P-3s3p 3 P Transitions of MgI

Summary We report the measurements of the³ D(3s4d)-³ P(3s3p)³ D(3s5d)-³ P(3s3p), and³ P(3p ²)-³ P(3s3p) transition frequency of MgI, the fine-structure separation and isotope shift between²⁴Mg and²⁶Mg. The measurements have been performed in a metastable atomic beam; a good agreement is found for data already existing in the literature. The accuracy of the measurements reported in this paper is mainly limited by the Doppler broadening of theI ₂ transitions used as a reference and by the precision in the knowledge of the related wavelengths.     

The gas phase infrared band contours of s-triazine and s-triazine-d3: The fundamentals of C3N3H3 and C3N3D3 and some overtone and combination bands of C3N3H3

The systematic application of band contour techniques to account for most of the observed features of the ir spectra of s-triazine and s-triazine-d₃ have been made as well as a critique as to the limitations of such methods. The experimental and computer methods used to study the gas phase infrared band contours of s-triazine and s-triazine-d₃ are out-lined. Contours of the five E′ fundamentals of s-triazine have been recorded under moderate resolution and analyzed to give the Coriolis constants $\text{ζ}{}_{\mathrm{i}}{}^{\mathrm{z}}$, i = 6–10. The effects of l-resonance are very apparent for ν₈ and ν₉, in the form of holes in the Q branches of these bands. Under the highest resolution available, ν₆ and ν₁₀ also show l-resonance effects. Values of the l-doubling constants $\text{q}{}_{\mathrm{i}}{}^{\mathrm{(+)}}$ were obtained for these four fundamentals. One of the parallel A₂″ fundamentals of C₃H₃N₃ (ν₁₂) has also been studied. It lies close to ν₁₀(E′) and an A × E type of second-order Coriolis resonance may be the cause of the intensity enhancement observed in the inner wings of the ν₁₂ and ν₁₀ bands. Hot bands of the type (ν_i + nν₁₄ ? nν₁₄) have been observed in the contours of ν₈, ν₁₀, and ν₁₂. This is felt to be responsible for the large difference between our observed zeta sum (?1.30) and the theoretical sum (?1.00).The gas phase infrared band contours of the five E′ and 2A₂″ fundamentals of C₃N₃D₃ have also been recorded under moderate resolution. From P-R separations and by computer simulation of the contours, values of the Coriolis constants $\text{ζ}{}_{\mathrm{i}}{}^{\mathrm{z}}$ have been obtained for the E′ modes. The effects of l-resonance have been observed for ν₈(E′) and ν₁₀(E′) and values of the l-doubling constants $\text{q}{}_{\mathrm{i}}{}^{\mathrm{(+)}}$ have been estimated. An extensive series of hot bands of the type (ν₁₂ + nν₁₄ ? nν₁₄) has been observed in the contour of the ν₁₂ (A₂″) fundamental. The mass effect on the Coriolis constants has been discussed.Infrared band contours of the overtone 2ν₇ and seven degenerate E′ combination bands of C₃N₃H₃ have been recorded under moderate resolution. Analysis of these contours using the P-R separation method and computer simulation of the contours has given values of $\text{ζ}{}_{\mathrm{<mtext>eff</mtext>}}{}^{\mathrm{z}}$ for these bands. Fermi resonance between 2ν₇ and ν₆ has been analyzed. The importance of considering both the observed contour as well as the observed frequency when assigning higher tone bands is illustrated.     

LaGaO3:RE3+(RE3+=Eu3+,Ho3+)的光谱

本文用固态反应合成了钙钛矿型的LaGaO3和LaGaO3:RE3+(RE3+=Eu3+,Ho3+)荧光体,并观察了物相随不同的激活离子浓度的变化。测量了化合物在室温下的反射光谱,激发光谱和荧光光谱。研究了Eu3+的D0→7F2和Ho3+的5S2→5I8的荧光强度与激活离子浓度的关系,发现了浓度猝灭,并得到了最大荧光强度的浓度值。     

Dielectric investigations of solid solutions SrTiO3-KTaO3 and SrTiO3-KNbO3

The temperature dependences of the dielectric constant and dielectric hysteresis loops in ceramic samples of (1 ? x)SrTiO_3?x KNbO₃ and (1 ? x)SrTiO_3?x KTaO₃ (0 ≤ x ≤ 0.3) solid solutions prepared using different heat treatments have been investigated. Phase diagrams of the studied solid solutions have been constructed in the T-x coordinates. It has been shown that, after quenching of samples (spontaneous cooling at room temperature after long-term heating at the sintering temperature of the ceramic samples), the temperature of the induced phase transition increases because of the weakening of random electric fields associated with nonisovalent impurities due to their “frozen” nonequilibrium redistribution. For small concentrations x, strong dielectric relaxation is observed in the temperature range of 150–250 K. A model of relaxing centers, which is based on the local charge compensation of heterovalent impurities, has been proposed.     

Infrared spectra of matrix isolated BH3NH3, BD3ND3, and BH3ND3

The infrared spectra of ammonia-borane, BH₃NH₃, and two of its deuterated isotropic species, BD₃ND₃ and BH₃ND₃, isolated in argon matrix at liquid hydrogen temperature have been measured. Well resolved bands for these three isotopic species have been observed for all the fundamentals. A complete frequency assignment based on C₃v molecular symmetry has been made. A set of force constants have been calculated from the data for the two isotopes BH₃NH₃ and BD₃ND₃ using a valence force field. The agreement between experiment and frequencies calculated from these force constants for the mixed isotopic species, BH₃ND₃, substantiates the present assignment.     

Terahertz Vibrational Modes in CH3NH3PbI3 and CsPbI3 Perovskite Films

JETP Letters - Films of CH3NH3PbI3 organometallic perovskite, which is currently considered as a promising basic material for new-generation solar cells, as well as films containing CsPbI3...     

Ba3La(BO3)3基质中Tb3+的光致发光

以高温固相法合成了Ba3La(BO3)3∶Tb3 发光材料。在254nm紫外光激发下,研究了Ba3La(BO3)3∶Tb3 的激发光谱、发射光谱、发光强度与Tb3 浓度的关系。确定了Ba3La(BO3)3基质中Tb3 的自身浓度猝灭机理;探讨了助熔剂LiCO、敏化剂Ce3 、Bi3 的加入对荧光粉的发光强度的影响。     

Modulated magnetic structures of ErPb3, HoPb3, ErTl3 and HoTl3

Neutron diffraction experiments have been carried out on the magnetically ordered phases of ErPb₃, HoPb₃, ErTl₃ and HoTl₃. The magnetic moments were found to be sinusoidally modulated with a propagation vector of (0, 0.2, 0.5) for the Pb-compounds and (0.38, 0.38, 0.16) for the Tl-compounds.Work supported by the Bundesministerium für Forschung und Technologie     

（LaO）3BO3中Eu^3＋和Sm^3＋的光致发光

研究了紫外光激发下，（ＬａＯ）３ＢＯ３基质中Ｅｕ＾３＋和Ｓｍ＾３＋的光谱性质，Ｅｕ＾３＋和Ｓｍ＾３＋的电荷迁移激发带及发光强度随组成和结构变化的规律性，并探讨了Ｅｕ＾３＋和Ｓｍ＾３＋自身浓度猝灭的机理。