| 1. |
- Yu, Yongle, et al.
(author)
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Supershell structure in trapped dilute Fermi gases
- 2005
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In: Physical Review A. Atomic, Molecular, and Optical Physics. - : American Physical Society. - 1050-2947 .- 1094-1622. ; 72:5
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Journal article (peer-reviewed)abstract
- We show that a dilute harmonically trapped two-component gas of fermionic atoms with a weak repulsive interaction has a pronounced super-shell structure: The shell fillings due to the spherical harmonic trapping potential are modulated by a beat mode. This changes the "magic numbers" occurring between the beat nodes by half a period. The length and amplitude of this beating mode depend on the strength of the interaction. We give a simple interpretation of the beat structure in terms of a semiclassical trace formula for the symmetry breaking U(3)→SO(3).
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| 2. |
- Mizielinski, M. S., et al.
(author)
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Electronic nonadiabatic effects in the adsorption of hydrogen atoms on metals
- 2005
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In: Journal of Chemical Physics. - : AIP Publishing. - 1089-7690 .- 0021-9606. ; 122:8
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Journal article (peer-reviewed)abstract
- The time-dependent, mean-field Newns-Anderson model for a spin-polarized adsorbate approaching a metallic surface is solved in the wide-band limit. Equations for the time evolution of the occupation of the spin dependent adsorbate states and for the nonadiabatic and nearly adiabatic adsorbate-surface energy transfer rates are derived. Numerical solutions are obtained using characteristic parameters derived from density functional theory calculations for the H/Cu(111) system. The time evolution of the model system is shown to be strongly nonadiabatic in the vicinity of the transition point between spin-polarized and nonpolarized ground states. Away from the spin transition the nonadiabatic energy transfer is in close agreement with the nearly adiabatic limit. Near the transition, nonadiabatic effects are large and the nearly adiabatic approximation fails.
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| 3. |
- Urban, Joachim, 1964, et al.
(author)
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Retrieval of vertical constituents and temperature profiles from passive submillimeter wave limb observations of the Martian atmosphere: a feasibility study
- 2005
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In: Applied Optics. - 1559-128X .- 2155-3165. ; 44:12, s. 2438-2455
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Journal article (peer-reviewed)abstract
- The investigation of the Martian atmosphere is of key importance for an understanding of the planets present and past. Passive limb observations of thermal radiation at submillimeter wavelengths in the 320-350-GHz range by use of a state-of-the-art satellite receiver on a low Mars orbit allow important parameters such as the mixing ratios of H2O, HDO, 12CO, 13CO, O3, and H2O2 as well as the thermal profile to be retrieved with high precision and unprecedented vertical range and resolution, providing valuable information for better understanding of the planet's water cycle, atmospheric dynamics, and photochemistry. The feasibility of these kinds of measurement is demonstrated by means of model simulations based on realistic atmospheric, spectroscopic, and instrumental parameters. Temperature can be retrieved to ∼90 km with half-scale height vertical resolution from single-scan measurements of emission lines of the long-lived species 12CO and 13CO. The global water-vapor distribution can be measured even under dry or wet conditions with good vertical resolution from the surface to ∼45 km, and simultaneous observations of HDO allow useful information on the D/H ratio up to an altitude of ∼30 km to be derived. The sensitivity of the limb-sounding technique also permits information on the photochemically important minor species O3 and H2O2 to be obtained. It is shown that spectral averaging may improve precision, altitude range, and resolution of the retrieved profiles. Other frequency bands are explored, and the 435-465-GHz range is suggested as a possible alternative to the 320-350-GHz range.
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| 4. |
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| 5. |
- Ögren, Magnus, 1977-, et al.
(author)
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Solitary waves in elongated clouds of strongly interacting bosons
- 2005
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In: Physical Review A. Atomic, Molecular, and Optical Physics. - : American Physical Society. - 1050-2947 .- 1094-1622. ; 72:2
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Journal article (peer-reviewed)abstract
- We examine the propagation of solitary waves in elongated clouds of trapped bosonic atoms as the confinement, the strength of the interatomic interaction, and the atom density are varied. We identify three different physical regimes and develop a general formalism that allows us to interpolate between them. Finally we pay special attention to the transition to the Tonks-Girardeau limit of strongly interacting bosons.
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| 6. |
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| 7. |
- Birgersson, Evert, et al.
(author)
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Binary fission-fragment yields from the reaction 251Cf(nth, f)
- 2005
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In: Nuclear fission and fission-product spectroscopy. - : American Institute of Physics. - 0735402884 ; , s. 349-352
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Conference paper (peer-reviewed)abstract
- The recoil mass spectrometer LOHENGRIN of the Laue-Langevin Institute, Grenoble has been used to measure the light fission-fragment mass yield and kinetic energy distributions from neutron-induced 252Cf*, using 251Cf as target material. ©2005 American Institute of Physics
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| 8. |
- Brack, M., et al.
(author)
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Uniform semiclassical trace formula for U(3) → SO(3) symmetry breaking
- 2005
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In: Journal of Physics A. - : Institute of Physics (IOP). - 0305-4470 .- 1361-6447. ; 38:46, s. 9941-9967
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Journal article (peer-reviewed)abstract
- We develop a uniform semiclassical trace formula for the density of states of a three-dimensional isotropic harmonic oscillator (HO), perturbed by a term . This term breaks the U(3) symmetry of the HO, resulting in a spherical system with SO(3) symmetry. We first treat the anharmonic term for small ε in semiclassical perturbation theory by integration of the action of the perturbed periodic HO orbit families over the manifold which is covered by the parameters describing their four-fold degeneracy. Then, we obtain an analytical uniform trace formula for arbitrary ε which in the limit of strong perturbations (or high energy) asymptotically goes over into the correct trace formula of the full anharmonic system with SO(3) symmetry, and in the limit ε (or energy) →0 restores the HO trace formula with U(3) symmetry. We demonstrate that the gross-shell structure of this anharmonically perturbed system is dominated by the two-fold degenerate diameter and circular orbits, and not by the orbits with the largest classical degeneracy, which are the three-fold degenerate tori with rational ratios ωr:ωφ ≤ N:M of radial and angular frequencies. The same holds also for the limit of a purely quartic spherical potential V(r) ∝ r4.
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| 9. |
- Da Silva, A. F., et al.
(author)
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Linear optical response of Si1-xGex compounds
- 2005
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In: Quantum Sensing and Nanophotonic Devices II. - : SPIE - International Society for Optical Engineering. - 081945706X ; 5732:1, s. 556-564
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Conference paper (peer-reviewed)abstract
- Si1-xGex is a good candidate as a substitute material for Si in a low-power and high-speed semiconductor device technologies. Optical devices, such as heterojunction bipolar transistors, are already in industrial production. The samples are grown on Si(001) with both n-and p-type impurities and with different Ge concentrations. The linear optical response of Si 1-x Gex is investigated theoretically using a full-potential linearized augmented plane wave method with respect to composition x. The calculated real and imaginary parts of the dielectric function ε e(ω) = ε1(ω) + iε 2(ω) were found to be in good agreement with recent spectroscopic ellipsometry measurements performed by Bahng et al., J. Phys.: Condens. Matter 13, 777 (2001). We also perform absorption measurements for different type of samples showing the variation of energy gaps as a function of Ge concentrations.
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| 10. |
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