Symmetry of the Barochronous Motions of a Gas

We study the system of nonlinear differential equations which expresses the constancy of the algebraic invariants of the Jacobian matrix for smooth vector fields in three-dimensional space. This system is equivalent to the equations of gas dynamics which describe the barochronous motions of a gas (the pressure and density depend only on the time). We present the results of computation of the admissible local Lie group and construction of the general solution of the system. We mention a few new problems that arise here.     

Spectroscopically determined potential energy surfaces of the H2O, H2O, and H2O isotopologues of water

Adiabatic potential energy surfaces (PESs) for three major isotopologues of water, H₂¹⁶O, H₂¹⁷O, and H₂¹⁸O, are constructed by fitting to observed vibration-rotation energy levels of the system using the nuclear motion program DVR3D employing an exact kinetic energy operator. Extensive tests show that the mass-dependent ab initio surfaces due to Polyansky et al. [O.L. Polyansky, A.G. Császár, S.V. Shirin, N.F. Zobov, P. Barletta, J. Tennyson, D.W. Schwenke, P.J. Knowles, Science 299 (2003) 539-542.] provide an excellent starting point for the fits. The refinements are performed using a mass-independent morphing function, which smoothly distorts the original adiabatic ab initio PESs. The best overall fit is based on 1788 experimental energy levels with the rotational quantum number J = 0, 2, and 5. It reproduces these levels with a standard deviation of 0.079 cm⁻¹ and gives, when explicit allowance is made for nonadiabatic rotational effects, excellent predictions for levels up to J = 40. Theoretical linelists for all three isotopologues of water involved in the PES construction were calculated up to 26 000 cm⁻¹ with energy levels up to J = 10. These linelists should make an excellent starting point for spectroscopic modelling and analysis.     

Third-order diamagnetic susceptibilities of hydrogenlike atoms

We develop a method for calculating diamagnetic susceptibilities based on higher-order perturbation theory for the wave function and energy of the excited states of the hydrogen atom with degeneracy of arbitrary multiplicity. We derive analytical expressions for third-order matrix elements in the spherical states |nlm〉 with fixed principal quantum number n and magnetic quantum number m. The formulas for the susceptibilities of doubly degenerate levels are represented in the form of radical-fractional relationships containing polynomials in the principal quantum number. We establish the existence of a monotonic interdependence between the absolute values of susceptibilities of the first three orders. We also present the results of numerical calculations for the states with n⩽6 and m⩽3 mixed by the field. Finally, for Rydberg states with large n and small m we detect the existence of a discontinuity in the interdependence of the susceptibilities at the boundary between the doublet and equidistant parts of the spectrum of diamagnetic sublevels with opposite parities. Zh. éksp. Teor. Fiz. 116, 838–857 (September 1999)     

Large tunable Rashba spin splitting of a two-dimensional electron gas in Bi2Se3

We report a Rashba spin splitting of a two-dimensional electron gas in the topological insulator Bi(2)Se(3) from angle-resolved photoemission spectroscopy. We further demonstrate its electrostatic control, and show that spin splittings can be achieved which are at least an order-of-magnitude larger than in other semiconductors. Together these results show promise for the miniaturization of spintronic devices to the nanoscale and their operation at room temperature.     

First Results of Ion Trapping in the Dresden EBIT II

Hyperfine Interactions - It is well known that many reinforced concrete structures are at risk of deterioration due to chloride ion contamination of the concrete or atmospheric carbon dioxide...     

High-pressure thermopower of sulfur

First measurements of the thermopower and transverse magnetoresistance of sulfur at ultrahigh pressures of up to ～40 GPa are reported. The conductivity of sulfur, as that of other elemental Group VI semiconductors (Te, Se), is shown to be due to valence band holes. The variation of band gap width is derived from the pressure dependence of thermopower. The observed negative magnetoresistance of sulfur at P ～ 30 GPa indicates a low hole mobility and suggests the existence of an indirect minimum gap in the electronic spectrum. The pressure-induced variation of the electronic structure of sulfur is discussed in terms of the Peierls lattice instability model.     

Observation of the second harmonic in the phase dependence of a superconducting current in Nb/Au/YBCO heterojunctions

The second harmonic in the dependence of a superconducting current on the phase difference of superconducting wave functions of the electrodes was observed experimentally in Nb/Au/(001)YBa₂Cu₃O_x heterojunctions. Possible reasons for its appearance were discussed within the framework of a mixed (d±s) symmetry order parameter of YBa₂Cu₃O_x.     

Thermoelectric study of the phase transitions in cerium at ultrahigh pressures from 0 to 20 GPa

The pressure dependences of the thermoelectric power S of Ce samples were measured at pressures P from 0 to 20 GPa in a synthetic diamond cell. The dependence of S on P was found to be nonmonotonic both in the region of transitions from the fcc (γ) phase to the modified fcc (α) phase followed by the transition to the body-centered monoclinic (α″) and the tetragonal (ε) phases at pressures of about 1, 5–6, and 12–15 GPa, respectively, and in the stability region of these phases. The thermoelectric power sign was found to be positive for all high-pressure Ce phases. The found S(P) dependence was compared with the published computational data on the electronic structure of the cerium phases. Cerium was taken as an example to demonstrate the advantage of the thermoelectric studies over other methods of investigation of phase transitions.