Spectral luminescence properties of Ca1 ? x Sr x F2:Ce3+ (0 < x <1) crystals

The luminescence, reflection, and luminescence excitation spectra of two-component Ca_{1 ? x} Sr _x F₂:Ce³⁺ (0.05 mol %) (x = 0.14, 0.25, 0.4, 0.6, and 0.75) have been studied at room temperature and T = 8 K. It is shown that the luminescence bands (upon 130-eV photon excitation) in the range of 200 to 400 nm are attributed to singlet and triplet self-trapped exciton luminescence and to 5d-4f transitions in Ce³⁺.     

Mössbauer study of Y2Fe17N x (x < 3) nitrides

⁵⁷Fe Mössbauer spectra of Y₂Fe₁₇N_x nitrides were measured. The hyperfine field (H _hf) and the average isomer shift for Y₂Fe₁₇ increase obviously after nitrogenation. Forx1.1, however, the averageH _hf varies only slightly, while the increase ofH _hfat each iron site is somewhat different and more pronounced at 4f dumbbell sites than at the other sites when the nitrogen concentration is increased. This means that the influence of the nitrogen atoms on the local magnetic properties of the iron atoms depends sensitively on the configuration of the nearest-neighbor atoms around the iron atoms. The results are compared with the⁸⁹Y NMR spectra of Y₂Fe₁₇N _x .This project was supported by the National Natural Science Foundation and the State Key Magnetism Laboratory of China.     

Entangled Eigenvectors of Scalar Fields φ1(x) - φ2(x) and П1(x) + П2(x)

We first demonstrate the precise Einstein-Podolsky-Rosen entanglement, which is inherent in quantum mechanics, in the context of quantum theory of complex scalar fields. We explicitly derive the entangled common eigenstates of φ₁(x) - φ₂(x) and П₁(x) + П₂(x) φ₁and φ₂ are two real components of the complex scalar field, and П₁ and П₂ are the corresponding conjugate fields) in the Fock space. The entangled eigenstates span a complete and orthonormal representation.     

Proton NMR study of the organic metal κ-(BETS)<Subscript>2</Subscript>Mn[N(CN)<Subscript>2</Subscript>]<Subscript>3</Subscript>

Magnetic properties of the organic conductor κ-(BETS)₂Mn[N(CN)₂]₃ above and below the temperature of the metal-insulator transition that occurs at T _MI ≈ 25 K are studied by ¹H NMR. The proton spectrum is shown to be determined by the static dipolar fields from Mn²⁺ localized moments, while the ¹H spin-lattice relaxation is dominated by fluctuating fields from Mn²⁺ electrons. The NMR data, both static (the spectra) and dynamic (the spin-lattice relaxation), indicate the freezing of Mn²⁺ moments into a short-range or an incommensurate long-range antiferromagnetic order below T _MI.     

Study of the parameters of the He(3 <Superscript>3</Superscript>S)-He(2 <Superscript>3</Superscript>P) line *

We have observed emission spectrum in dense plasmas of helium excited by a corona discharge at 706.69 nm. In continuation of an analysis of spectra obtained in gaseous helium at 300 K, we report on a study of the line parameters of the observed spectra. We discuss the major importance of temperature and perturber density in the broadening, shift and asymmetry measured from calculated profiles within a unified line shape semi-classical theory. The comparison is done with existing data derived from experimental spectra at 300 K. The theoretical work is extended at lower temperatures down to 40 K.     

Synthesis,structural characterization and ionic conductivity of NASICON-type Ba<Subscript>x/2</Subscript>Li<Subscript>1-x</Subscript>Ti<Subscript>2</Subscript>(PO<Subscript>4</Subscript>)<Subscript>3</Subscript> (0.4 ≤ x ≤ 1) materials

The NASICON series, with formula Ba_x/2Li_1-xTi₂(PO₄)₃ (0.4 ≤ x ≤ 1), has been prepared by solid-state reaction and characterized by X-ray diffraction (XRD), Fourier transform infrared (FTIR), Raman, nuclear magnetic resonance (NMR) and impedance spectroscopy (IS). XRD patterns of samples indicated the formation of single phases with rhombohedral structure (space group R-3c). The Rietveld analysis of XRD patterns was performed to deduce location of Li and Ba ions. FTIR, Raman, and NMR techniques showed the only presence of isolated PO₄ groups in analyzed phosphates. ³¹P MAS-NMR spectra were used to investigate Li and Ba distribution and ⁷Li MAS-NMR spectra to discriminated Li ions with different mobility in conduction paths. A maximum total conductivity of 2.5 × 10^?7 S cm^?1 and a minimum activation energy of 0.47 eV were obtained at room temperature for Ba_0.3Li_0.4Ti₂(PO₄)₃ (x = 0.6).     

Consistent α-cluster description of the <Superscript>12</Superscript>C(0<Stack><Subscript>2</Subscript><Superscript>+</Superscript></Stack>) “hoyle” resonance

The near-threshold ¹²C(0₂⁺) resonance provides unique possibility for fast helium burning in stars, as predicted by Hoyle to explain the observed abundance of elements in the Universe. Properties of this resonance are calculated within the framework of the α cluster model whose two-body and three-body effective potentials are tuned to describe the α-α scattering data, the energies of the 0₁⁺ and 0₂⁺ states, and the 0₁⁺-state rootmean-square radius. The extremely small width of the 0₂⁺ state, the 0₂⁺ → 0₁⁺ monopole transition matrix element, and transition radius are found in remarkable agreement with the experimental data. The 0₂⁺-state structure is described as a system of three α particles oscillating between the ground-state-like configuration and the elongated chain configuration whose probability exceeds 0.9.     

Superconductivity at normal pressure in κ-(BEDT-TTF)<Subscript>2</Subscript>Cu[N(CN)<Subscript>2</Subscript>]Cl crystals

Single crystals of the κ-(BEDT-TTF)₂Cu[N(CN)₂]Cl cation-radical salt are obtained. These crystals exhibit metallic properties and pass to a superconducting state with T_c = 11.5 K at ambient pressure.     

Cold and ultracold collisions of MgH (<Superscript>2</Superscript>Σ<Superscript>+</Superscript>) with helium

The cross sections for rotational, fine-structure and projection-change transitions in collision of MgH (²Σ⁺) molecule with ³He and ⁴He atoms were computed at cold and ultracold temperatures using the ab initio potential energy surface. The significant suppression feature and resonance pattern caused by spin-rotation interaction were found and discussed. The collisions exhibit a strong isotope effect in the ultracold regime. The rotational relaxations of the fine-structure excited energy levels tendentiously preserve the F index. The ratio of the cross sections for elastic and spin-flipping collision with ³He partner is always greater than seven orders of magnitude for the energy range 10^-6−1cm^-1 and suggests the MgH molecule is a good candidate for ³He buffer gas cooling.     

Analysis of Ω<Subscript>c</Subscript><Superscript>*</Superscript>(css) and Ω<Subscript>b</Subscript><Superscript>*</Superscript>(bss) with QCD sum rules

In this article, we calculate the masses and residues of the heavy baryons Ω_c ^*(css) and Ω_b ^*(bss) with spin–parity with the QCD sum rules. The numerical values are compatible with the experimental data and other theoretical estimations. PACS 14.20.Lq, 14.20.Mr     

Canonical interpretation of the <Emphasis Type="Italic">η</Emphasis><Subscript>2</Subscript>(1870)

We argue that the mass, production, total decay width, and decay pattern of the η ₂(1870) do not appear to contradict with the picture of it as being the conventional 2 ¹ D ₂ q[`(q)]q\bar{q} state. The possibility of the η <sub>2</sub>(1870) being a mixture of the conventional q[`(q)]q\bar{q} and a hybrid is also discussed.     

Radiation widths of resonances in the <Superscript>40</Superscript>Ar(pγ)<Superscript>41</Superscript>K reaction

The excitation function for the ⁴⁰Ar(pγ)⁴¹K reaction at the accelerated proton energy E _p= 450–2700 keV is studied. Positions of 168 resonances identified as levels of the ⁴¹K nucleus are observed in this energy range. The data for the proton energy E _p < 1 MeV and E _p > 2 MeV are obtained for the first time. Relative yields of γ rays observed in the decay of the resonances are calculated from a comparison with the yield of the calibrating resonance at E _p= 1102 keV. Total radiation widths of the resonances are calculated on the basis of the data obtained.     

The resonance-like structure observed in the <Superscript>40</Superscript>Ar(pγ)<Superscript>41</Superscript>K reaction

The excitation function of the ⁴⁰Ar(pγ)⁴¹K reaction in the energy range of accelerated protons E _p = 1.0–3.0 MeV was measured. Twelve new resonance states were revealed in the range E _p > 2.6 MeV. The strengths of all measured resonances were determined (for more than 200 states). A resonance-like structure with a center of gravity of 10.2 ± 0.5 MeV was identified; this agrees with the dependence of the center of gravity of the resonance-like structure found earlier on A in the nuclei of the sd shell.     

Staggered spin order of localized π-electrons in the insulating state of the organic conductor κ-(BETS)<Subscript>2</Subscript>Mn[N(CN)<Subscript>2</Subscript>]<Subscript>3</Subscript>

The magnetic properties of the conduction π-electron system of κ-(BETS)₂Mn[N(CN)₂]₃ have been probed using ¹³C NMR. At ambient pressure, the metal-insulator transition observed in the resistivity measurements below T ? 23 K is shown to be accompanied by ordering of the π-spins in a long-range staggered structure. As the metal-insulator transition is suppressed by applying a small pressure of ～0.5 kbar, the π-spin system maintains the properties of the metallic state down to 5 K.     

Investigation of the reaction D(<Superscript>4</Superscript>He, γ)<Superscript>6</Superscript>Li at ultralow energies

The cross section of the reaction D(⁴He, γ)⁶Li with titanium and zirconium deuterides as targets is measured for incident ⁴He⁺ ion energies of 30 and 36 keV, respectively. The ion beam is generated by a Hall pulsed plasma accelerator. For the first time, upper limits on the cross section of the reaction D(⁴He, γ)⁶Li at ultralow energies are imposed (at 90% confidence level): σ ≤ 1.2 × 10^?35 cm² for the TiD₂ target and E(⁴He⁺) = 30 keV, and σ ≤ 7 × 10^?36 cm² for the ZrD₂ target and E(⁴He⁺) = 36 keV     

The resonance-like structure observed in the <Superscript>25</Superscript>Mg(p, γ)<Superscript>26</Superscript>Al reaction

The gamma decay of resonance-like structure (RLS) observed in the ²⁵Mg(p, γ)²⁶Al reaction in the region of excitation energies of 7–9 MeV is studied, and the excitation function of this reaction is measured. The resonance transition strengths of states in the 1.4–2.0 MeV range of accelerated proton energies are determined. The resulting strength distributions of M1 transitions between the resonance states and the low-lying bound states in ²⁶Al are of a resonance nature. The position of the center of gravity of magnetic dipole resonance for the ground state in ²⁶Al is 7.92 MeV, and the total MDR transition strength is 5.7 MeV × μ _N ² .