Structure of strange attractor and homoclinic bifurcation of two-dimensional cubic map

The structure of a strange attractor of the two-dimensional cubic map with jacobian J is investigated in the cases J ≈ 0 and J ≈ 1. The strange attractor has a selfsimilar three-belt structure. The threshold of homoclinic bifurcation is calculated for J ≈ 1.     

ICP-MS/ICP-AES快速测定东北大豆中有益元素和重金属含量

在没有被转基因大豆入侵前,对于东北大豆的研究将为种质资源保护大豆提供重要的参考数据。文章用ICP-MS/ICP-AES技术对东北嫩江地区普遍栽培的10个大豆品种中的全元素进行了研究。表明东北大豆中含有丰富的人体必需元素,其大量元素(含量超过μg·g-1级)的含量从高到低是K>P>Mg>Ca>Fe>Rb>Mn≈Zn>Si≈Na≈Al≈Ba≈Ni≈Cu,有益微量元素B,Mo和Se含量在10～2 000 ng·g-1之间。丰量元素Fe,Mn和Zn含量达到20～80 μg·g-1之间。除了上述有益元素以外,东北大豆中重金属含量均达到国家标准,但是Cr的含量接近200 ng·g-1,应当加强控制。     

Measurement of density, temperature, and electrical conductivity of a shock-compressed nonideal nitrogen plasma in the megabar pressure range

Kinematic and thermodynamic parameters of shock-compressed liquid nitrogen are measured behind the front of a plane shock wave using plane wave and hemispherical shock wave generators. In these experiments, high values of compression parameters (shock-compressed hydrogen density? ≈ 3.25 g/cm³ and temperature T≈ 56000 K at a pressure of P ≈ 265 GPa) are attained. The density, pressure, temperature, and electrical conductivity of the nonideal plasma of shock-compressed liquid nitrogen are measured. A nearly isochoric behavior of the nitrogen shock adiabat is observed in the pressure range P = 100–300 GPa. The thermodynamics of shock-compressed nitrogen is an alyzed using the model of the equation of state in the quasi-chemical representation (SAHA code) as well as the semiempirical wide-range equation of state developed at the Institute of Experimental Physics. Experimental results are interpreted on the basis of calculations as the fixation of the boundary of transition of shock-compressed nitrogen from the polymer phase to the state of a strongly nonideal plasma at P ≈ 100 GPa, ? ≈ 3.4 g/cm³.     

Intensity anomalies in the spectra of 2p-3d multiplets of A1XI and A1X observed on the rear surface of laser-irradiated foils

The relative intensities of the 2p-3p multiplets of A1XI (λ ≈ 52 Å) and A1X (λ ≈ 55 Å) emitted from the plasma produced by the irradiation of 9 μm thick aluminium foils with a neodymiun laser focussed to peak intensities ≈ × 10₁₅ Wcm^-2 have been recorded with spatial resolution of ≈ 30 μm. The measured relative intensities indicate that there is partial intermixing of the quantum states near the 3d states of A1XI and A1X in plasma expanding from the rear of the laser-irrdiated foils. The spectra recorded are consistent with the rear plasma being produced by superthermal electrons travelling around the foil edge and striking the back of the foil.     

Formation of Nanoscale Cracks and Fractoluminescence upon Destruction of Carbon Ceramics

Physics of the Solid State - We obtained a Raman spectrum for a surface layer of porous carbon ceramic (porosity ≈5%) of ≈80 nm thick. The analysis of the spectrum showed that...     

Asymmetric metal-insulator transition in disordered ferromagnetic films

We present experimental data and a theoretical interpretation of the conductance near the metal-insulator transition in thin ferromagnetic Gd films of thickness b ≈ 2-10 nm. A large phase relaxation rate caused by scattering of quasiparticles off spin-wave excitations renders the dephasing length L(?) ? b in the range of sheet resistances considered, so that the effective dimension is d = 3. The conductivity data at different stages of disorder obey a fractional power-law temperature dependence and collapse onto two scaling curves for the metallic and insulating regimes, indicating an asymmetric metal-insulator transition with two distinctly different critical exponents; the best fit is obtained for a dynamical exponent z ≈ 2.5 and a correlation (localization) length critical exponent ν- ≈ 1.4 (ν+ ≈ 0.8) on the metallic (insulating) side.     

Foil-excited Rydberg states of fast oxygen ions

The population of Rydberg states in fast oxygen ions emerging from solid targets is found to be more than ≈ 500 times as large as expected from Coulomb capture of target electrons in last-layer collisions. Furthermore, we find a population depletion for quantum states near n ≈ 10.     

Formation of textured Ni(200) and Ni(111) films by magnetron sputtering

The effect of the working gas pressure (P ≈ 1.33–0.09 Pa) and the substrate temperature (T_s ≈ 77–550 K) on the texture and the microstructure of nickel films deposited by magnetron sputtering onto SiO₂/Si substrates is studied. Ni(200) films with a transition type of microstructure are shown to form at growth parameters P ≈ 0.13–0.09 Pa and T_s ≈ 300–550 K, which ensure a high migration ability of nickel adatoms on a substrate. This transition type is characterized by a change of the film structure from quasi-homogeneous to quasi-columnar when a film reaches a critical thickness. Ni(111) films with a columnar microstructure and high porosity form at a low migration ability, which takes place at P ≈ 1.33–0.3 Pa or upon cooling a substrate to T_s ≈ 77 K.     

Interaction between 193-nm pulsed laser radiation and α-alumina

The threshold power density of 15-ns laser pulses with a wavelength 193 nm is determined for basic modes of interaction between the radiation and α-alumina. As power density Q on the target varying in the range 0.001–100 MW/cm² increases, first the interaction mechanism changes from single-photon interaction to two-photon interaction at Q ≈ 0.1 MW/cm². At Q ≈ 5 MW/cm², the material sublimates and then the sublimation products ionize at Q ≈ 15 MW/cm². At Q ≈ 100 MW/cm², the material is removed from the surface at a rate of ≈ 10 nm per pulse.     

On the tricritical point in MnSi under high pressures

The magnetic susceptibility of a MnSi single crystal is measured in the region of the ferromagnetic phase transition under pressures up to 0.8 GPa in compressed helium. It is found that the tricritical point on the phase-transition curve corresponds to a much lower pressure and a considerably higher temperature (P _tr ≈ 0.355 GPa and T _tr ≈ 25.2 K) than was reported earlier (P _tr ≈ 1.2 GPa and T _tr ≈ 12 K). New results impose certain limitations on theoretical analysis of tricritical phenomena in MnSi.     

Measurement of quantum noise in a carbon nanotube quantum dot in the Kondo regime

The current emission noise of a carbon nanotube quantum dot in the Kondo regime is measured at frequencies ν of the order or higher than the frequency associated with the Kondo effect k(B)T (K)/h, with TK the Kondo temperature. The carbon nanotube is coupled via an on-chip resonant circuit to a quantum noise detector, a superconductor-insulator-superconductor junction. We find for hν ≈ k(B)T(K) a Kondo effect related singularity at a voltage bias eV ≈ hν, and a strong reduction of this singularity for hν ≈ 3k(B)T(K), in good agreement with theory. Our experiment constitutes a new original tool for the investigation of the nonequilibrium dynamics of many-body phenomena in nanoscale devices.     

Continuous-wave, multiple-order rotational Raman generation in molecular deuterium

We demonstrate the generation of ≈10 rotational sidebands using continuous-wave stimulated Raman scattering in molecular deuterium. The generation occurs inside a high-finesse cavity at molecular gas pressures of ≈0.1?atm.     

Charge resonance enhanced ionization of CO2 probed by laser Coulomb explosion imaging

The process by which a molecule in an intense laser field ionizes more efficiently as its bond length increases towards a critical distance R(c) is known as charge resonance enhanced ionization (CREI). We make a series of measurements of this process for CO(2), by varying pulse duration from 7 to 200 fs, in order to identify the charge states and time scales involved. We find that for the 4+ and higher charge states, 100 fs is the time scale required to reach the critical geometry ≈ 2.1 ? and <θ(OCO)> ≈ 163° (equilibrium CO(2) geometry is ≈ 1.16 ? and <θ(OCO)> ≈ 172°). The CO(2)(3+) molecule, however, appears always to begin dissociation from closer than 1.7 ? indicating that dynamics on charge states lower than 3+ is not sufficient to initiate CREI. Finally, we make quantum ab initio calculations of ionization rates for CO(2) and identify the electronic states responsible for CREI.     

New photoluminescence defect spectra in silicon irradiated at 100 K: Observation of interstitial carbon?

We report photoluminescence spectra of defects in irradiated silicon which are stable below room temperature. No-phonon lines (STI)⁰ at ≈ 856 meV, ST2 at ≈ 1115 meV, and ST3 at ≈ 1126 meV are observed along with a broad emission band extending from 0.7 to 1 eV. The ST1 defect studied in detail is a deep hole trap at ≈ E_v + 0.25 eV, which in addition can bind an electron loosely. Piezospectroscopy shows that the defect is essentially <100 > axial symmetric with slight distortion to C_1h. The absence of Zeeman splittings confirms the deep hole binding in an axially symmetric potential. The independence of dopants, the annealing behaviour, and comparison to EPR and IR active defects suggest a correlation of the ST1 defect with interstitial carbon.     

Valence band contributions to photoluminescence excitation spectra of tightly bound holes in zincblende semiconductors

Photoluminescence excitation (PLE) spectra of deep acceptor states in ZnSe, for example the Cu-related luminescence band at ≈1.95 eV, contain a prominent excitation band at ≈3.25 eV. This band lies above the structure marking the lowest direct E_O band gap E_g by the spin-orbit splitting energy Δ of the valence bands at Γ. The higher energy feature is either absent or greatly de-emphasised in the PLE spectra of shallow acceptor states in ZnSe and of the oxygen iso-electronic trap in ZnTe, where the electron rather than the hole is tightly bound. However, a significant PLE component at E_g + Δ is observed for deep acceptor-like states in ZnTe, where Δ is ≈0.95 eV. Efficient PLE at E + Δ for luminescence from deep acceptor-like states is shown to be consistent with the extended wave-vector contributions to the bound state wave-functions of holes of binding energies ≈Δ.     

Filamentary actuation on the surface of bodies contoured by high-speed flows

In this study, we focus our attention on the ability of a filamentary discharge to affect the shock waves patterns generated by a test model of diamond shape placed in a high-speed airflow. Our results indicate that no significant changes could be detected at moderate supersonic regimes (Ma≈1.8) or at transonic conditions (Ma≈0.8) even when the filament traversed the shock.     

Experimental proof of the existence of the A1 meson

In partial wave analyses of the (π^?π^?π⁺) system, substantial shape changes of the 1⁺S (?π) intensity as a function of t, and relative phase changes of ≈ 90°, provide compelling evidence for a resonant A₁ of mass ≈ 1280 MeV and width ≈ 300 MeV.     

Study of positron lifetimes in α, β and γ cerium at high pressures

The positron lifetimes in the α, β and γ phases of Ce have been measured by applying hydrostatic pressure (up to 1.4 GPa) and by reducing the temperature (to 80 K). Two-component fitting programs showed that the main component ( ≈ 90%) had virtually the same mean lifetime ( ≈ 233 ps) in all three phases. The uncertainty in each lifetime was ±2 ps. With this high precision, our results are in agreement with those of band calculations which give the same number of 4f electrons ( ≈ 1.2) in all phases.     

Phase transitions in iridium oxide films

We report studies of SIROFs by differential thermal analysis (DTA), evolved gas analysis (EGA), and scanning electron microscopy (SEM). SIROFs undergo an irreversible exothermic transition at ≈300°C associated with ≈1 eV energy release and no decomposition. There is a second endothermic transition at ≈700°C, which is associated with dehydration. After undergoing the first transition, SIROFs lose their good electrochromic and electrocatalytic properties.     

Temperatures determined from neutron emission in nucleus-nucleus collisions

Most neutron spectra from ¹⁴N+¹⁶⁵Ho collisions at 35 MeV/nucleon are described by two moving thermal sources, one at a temperature of ≈2.5 MeV and the other of ≈8 MeV. Resonances in gragment-neutron relative velocity spectra are used to determine a temperature from the relative populations of excited states of ¹³C nuclei. There is a discrepancy with the equilibrium assumption in that the fitted value, ≈1 MeV, does not match that of either thermal source.