Semiclassical Calculations of Recurrence Spectra for Lithium Atoms in Parallel Electric and Magnetic Fields

By using the region-splitting consistent and iterative method,we calculate the recurrence spectra of lithium atoms in parallel strong external electric and magnetic fields,and obtain the novel resonance structure in the photoabsorption spectrum above the ionization threshold with a constant scaled electric field at F=0.036,and a scaled energy at ε＝0.58 and ε=0.006,respectively.The results are compared with those of hydrogen obtained by using standard closed orbit theory.It is demonstrated that the core-scattered effects exhibited in combination recurrence play a great role.     

Mechanical Properties of Ti–Ni–Ta and Ti–Ni–Ta–Si Surface Alloys Synthesized on Titanium Nickelide Substrates

Technical Physics - The physical-mechanical properties of Ti-Ni-Ta and Ti-Ni-Ta-Si surface alloys (about 1 μm thick) synthesized on TiNi substrates by the additive thin-film electron-beam...     

Stress Corrosion Cracking of Metals and Alloys in Aggressive H2S–CO2–Cl– Environments

Technical Physics - We have analyzed the data on stress corrosion cracking of steels of various grades in acidic H2S–CO2–Cl– solutions. For the active region of corrosion, we have...     

Stark–Zeeman and Blokhintsev Spectra of Rydberg Atoms

Journal of Experimental and Theoretical Physics - The problem of Rydberg atomic spectra in crossed electric F and magnetic B fields (combined Stark–Zeeman effects), as well as an oscillating...     

Comparative Analysis of the Interaction Potentials of the Ozone Molecule with Atoms of Noble Gases: O3–Ar and O3–He Complexes

Russian Physics Journal - The interaction energy of the ozone molecule with atoms of noble gases (Ar and He) is analyzed. The coupled cluster methods CCSD(T) and CCSD(T)-F12 with orbital basis sets...     

Controlled synthesis and analysis of He–H+3 in a 3.7 K ion trap

Complexes of the triatomic hydrogen ion with helium were synthesised in a low-temperature 22-pole rf ion trap at He number densities of up to 10¹⁶ cm^?3. Absolute ternary rate coefficients for sequentially attaching He atoms have been determined from the growth of complexes with increasing storage time. The number of helium-tagged ions is significantly reduced when increasing the nominal temperature from 4 to 25 K. Competition between attachment and dissociation via collisions leads to stationary He_n–H⁺₃ (n up to 9) distributions. State-specific excitation of the trapped H⁺₃ ions via IR transitions significantly reduces the formation of complexes. Tuning the laser to Δv₂ = 1 transitions in the range of 2726 cm^?1 leads to LIICG lines, i.e., to spectra caused by laser-induced inhibition of complex growth. In addition, almost 100 lines have been found between 2700 and 2765 cm^?1, which are attributed to laser-induced dissociation of the in situ formed He–H⁺₃ complex ions. These lines are not yet assigned; however, their absorption strength, statistics and predissociation lifetimes provide interesting information on both the stable complexes as well as on scattering resonances in low-energy H⁺₃+He collisions. New calculations of the potential energy surface will help to analyse the dissociation spectrum. There are some indications that para-H⁺₃ is enriched under the conditions of the present experiment.     

Calculations of potential of mean force: application to ion-pairs and host–guest systems

ABSTRACT

We report the calculation of the potential of mean force (PMF) of different types of associations by various techniques: two no biased methods (thermodynamic integration and finite difference thermodynamic integration), a constraint biased technique (adaptive biasing force) and an umbrella biased method (umbrella sampling). We apply these methodologies to the association between two methane molecules in water, to the formation of an ion pair in water and to the formation of an insertion complex between a macrocycle and a cation. The different PMFs are compared to each other on the basis of the depth of the free energy minimum and on the location of different specific points.     

Structure identification and site preference of Ta and Cd in Ti–Pd alloys: A first-principle study

By means of a density functional theory approach, we studied the electric field gradients (EFG) in Ta and Cd-doped Ti–Pd intermetallics. Our results confirmed the previous experimental findings that the TiPd₂ low-temperature structure is orthorhombic and established that Ta substitutes for Ti in this structure. The temperature increase above 650 K changes the Ta impurity position in the lattice. Similar changes for the Cd doped system were not confirmed, as Cd is most likely to occupy Pd lattice sites in both low and high-temperature phases. In the case of TiPd, our calculations suggested that Ta substitutes for Ti in the low-temperature phase, while Cd probably can substitute on both Ti and Pd crystallographic sites.     

Modeling of Radiation-Induced Segregation in Fe–Cr–Ni Alloys

Physics of the Solid State - In the model of radiation-induced segregation based on the first and second Fick laws and taking into account the inverse Kirkendall effect, concentration profiles of...     

Laser Cooling and Trapping of Sodium Atoms in Magneto-optical Trap

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Particle polarizations in decays of5HeΛ and4HΛhypernuclei

Nucleon polarizations are examined in the hypernucleus decays⁵He, ⁴He + p + _–,⁴H, ³H + p + _–, and⁴H, ³He + n + _–. The effect of the strong interaction in the final state is taken into account. A significant role is predicted for the resonance interaction in the p-⁴He system in the formation of the proton polarization in the⁵He decay. It is also shown that in the⁴H, ³H + p + _– decay the proton-polarization components should attain significant magnitudes, while in the charge-exchange decay⁴H, ³He + n + _–, the neutron polarization is expected to be not too large.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 10, pp. 100–103, October, 1988.     

Atomic structure of the Zr–He,Zr–vac,and Zr–vac–He systems: First-principles calculation

The ab initio investigations have been performed for the atomic structure of the Zr–He, Zr–vac, and Zr–vac–He systems with concentrations of helium atoms and vacancies (vac) of ~6 at %. A heliuminduced instability of the zirconia lattice has been revealed in the Zr–He system, which disappears with the formation of vacancies. The most preferred positions of impurities in the metal lattice have been determined. The energy of helium dissolution and the excess volume introduced by helium have been calculated. It has been established that the presence of helium in the Zr lattice leads to a significant decrease in the energy of vacancy formation.     

Crystallographic Features of the α-Phase Structure in Hafnium and Hafnium–Titanium Alloys

Technical Physics - The structure of a hafnium crystal undergoing β → α (bcc → hcp) polymorphic transformation upon gradual cooling and the structure of Hf55Ti45 and Hf30Ti70...     

Electrical properties and microstructural characterization of Ni/Ta contacts to n-type 6H–SiC

A Ni/Ta bilayer is deposited on n-type 6H–Si C and then annealed at different temperatures to form an ohmic contact. The electrical properties are characterized by I–V curve measurement and the specific contact resistance is extracted by the transmission line method. The phase formation and microstructure of the Ni/Ta bilayer are studied after thermal annealing. The crystalline and microstructure properties are analyzed by using glance incident x-ray diffraction(GIXRD),Raman spectroscopy, and transmission electron microscopy. It is found that the transformation from the Schottky to the Ohmic occurs at 1050?C and the GIXRD results show a distinct phase change from Ta2 C to Ta C at this temperature. A specific contact resistance of 6.5×10-5?·cm2is obtained for sample Ni(80 nm)/Ta(20 nm)/6H–Si C after being annealed at 1050?C. The formation of the Ta C phase is regarded as the main reason for the excellent Ohmic properties of the Ni/Ta contacts to 6H–Si C. Raman and TEM data reveal that the graphite carbon is drastically consumed by the Ta element, which can improve the contact thermal stability. A schematic diagram is proposed to illustrate the microstructural changes of Ni/Ta/6H–Si C when annealed at different temperatures.     

Kinetics and Phase Transformations during the Decomposition of Supersaturated Solid Solutions of Magnesium in Mg–Dy–Sm Alloys

Kinetics and phase transformations are studied for the previously unconsidered decomposition of supersaturated solid solution in magnesium-based alloys Mg–Dy–Sm. The decomposition of solid solution slows when there is an increase in % Dy: % Sm ratio in the alloys. Mg–Sm and Mg–Dy alloys grow harder when Dy and Sm are added to them, respectively. Products of decomposition in ternary Mg–Dy–Sm alloys are the same as in binary alloys Mg–Dy and Mg–Sm but contain combinations of Dy and Sm.     

Solutions of the Dirac–Fock Equations for Atoms¶and Molecules

The Dirac-Fock equations are the relativistic analogue of the well-known Hartree-Fock equations. They are used in computational chemistry, and yield results on the inner-shell electrons of heavy atoms that are in very good agreement with experimental data. By a variational method, we prove the existence of infinitely many solutions of the Dirac-Fock equations "without projector", for Coulomb systems of electrons in atoms, ions or molecules, with Z h 124, N h 41, N h Z. Here, Z is the sum of the nuclear charges in the molecule, N is the number of electrons.     

Anomalous Electrical Conductivity and Magnetization in Fe–Cr–Ni Austenite–Martensite Alloys

Technical Physics - We have measured the temperature dependence of the resistivity and magnetization of a special steel of the Fe–Cr–Ni austenite–martensite class in a wide...     

The Role of Transition Metals in Crystallization of Amorphous Al–Ni–Co–Yb Alloys

Technical Physics - Al86Ni4Co4Yb6 and Al86Ni6Co2Yb6 metallic ribbons have been obtained by a standard planar flow method. According to X-ray diffraction data, the ribbons are amorphous. Their...     

Characteristics of laser and current pulses in a He–SrCl2 vapor laser

An experimental investigation on the characteristics of laser and current pulses in a He–SrCl₂ vapor laser is carried out. The temporal dependences of the discharge current pulse on the laser pulses at the 1.09 μm, ～3 μm and 6.45 μm lines in strontium atoms and ions are measured and analyzed under different laser output powers. It is found that all laser pulses appear at the falling edge of the current pulse and shift forward to the current pulse with increasing laser output power.