| 1. |
- Aguilar, A., et al.
(författare)
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Double photodetachment from the Cl[-]ion
- 2004
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Ingår i: Physical Review A - Atomic, Molecular, and Optical Physics. - 2469-9926 .- 2469-9934. ; 69:2
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Tidskriftsartikel (refereegranskat)abstract
- The correlated process involving the photodetachment of two electrons from the [Formula Presented] ion has been investigated over the photon energy range 20–45 eV. In the experiment, a beam of photons from the Advanced Light Source (ALS) was collinearly merged with a counterpropagating beam of [Formula Presented] ions from a sputter ion source. The [Formula Presented] ions produced in the interaction region were detected, and the normalized signal was used to monitor the relative cross section for the reaction. An absolute scale for the cross section was established by measuring the spatial overlap of the two beams and by determining the efficiency for collection and detection of the [Formula Presented] ions. The overall magnitude and shape of the measured cross section for this process agrees well with an R-matrix calculation. The calculation identifies the dominant mechanism leading to the production of the [Formula Presented] ion as being a direct nonresonant process involving the ejection of a pair of electrons from the valence shell. Less important is the indirect nonresonant process that involves the production and decay of core-excited and doubly excited states of the Cl atom in an intermediate step. Direct and indirect resonant mechanisms involving the excitation of a single [Formula Presented] core electron or more than one valence electron of the [Formula Presented] ion were found to be insignificant in the energy range studied.
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| 2. |
- Amusia, MY, et al.
(författare)
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Directed motion of electrons in gases under the action of photon flux - art. no. 052512
- 2001
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Ingår i: PHYSICAL REVIEW A. - : AMERICAN PHYSICAL SOC. - 1050-2947. ; 6305:5, s. 2512-
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Tidskriftsartikel (refereegranskat)abstract
- The phenomenon of directed motion of electrons and ions in gases under the action of ionizing radiation pressure is investigated. It is shown that for photon energies from the thresholds of atomic photoionization to several keV the photoionization process
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| 3. |
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| 4. |
- Andersson, L. Mauritz, et al.
(författare)
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Nonadiabatic effects in the photoelectron spectra of HCl and DCl. II. Theory
- 2002
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Ingår i: Physical Review A. Atomic, Molecular, and Optical Physics. - 1050-2947 .- 1094-1622. ; 65:1
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Tidskriftsartikel (refereegranskat)abstract
- The vibrationally resolved photoelectron spectra of HCl and DCl in the 25-28 eV region were computed using a time-dependent approach for the nuclear dynamics. The spectral features cannot be understood without including a nonadiabatic coupling between the dissociative 3 (2)Sigma(+) state and the bound 4 (2)Sigma(+) state in the adiabatic picture. Alternatively, in the diabatic picture a dissociative two-hole-one-particle state interacts with a bound one-hole state. The molecular system is of intermediate coupling strength, i.e., it cannot be described by a single potential-energy curve. The interaction between a bound and a dissociative state leads to Fano resonances superimposed on a broad back-round, as observed in the experimental spectra [Burmeister et al., Phys. Rev. A 65, 012704 (2001)]. From modified potential-energy curves, all features of the experimental spectra, including Fano resonance parameters and lifetimes, were reproduced. From the simulations we observe that two additional peaks in the experimental DCl spectra should appear if the resolution were to be enhanced to around 10 meV.
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| 5. |
- Arve, Per, et al.
(författare)
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Propagation of two-dimensional pulses in electromagnetically induced transparency media
- 2004
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Ingår i: Physical Review A. Atomic, Molecular, and Optical Physics. - 1050-2947 .- 1094-1622. ; 69:6, s. 063809-
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Tidskriftsartikel (refereegranskat)abstract
- The propagation in two dimensions of "optical" pulses in electromagnetically induced transparency media is analyzed. Results are presented for coupled Maxwell-Bloch equations with slowly varying envelope approximation, for both adiabatic and nonadiabatic situations. The possibility of changing the direction of the pulse by a switch of control beam direction is investigated in detail.
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| 6. |
- Asplund, R., et al.
(författare)
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Reconstructing the discrete Wigner function and some properties of the measurement bases
- 2001
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Ingår i: Physical Review A. Atomic, Molecular, and Optical Physics. - 1050-2947 .- 1094-1622. ; 6401:1
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Tidskriftsartikel (refereegranskat)abstract
- We derive a direct reconstruction algorithm for the discrete Wigner function through different types of measurements. For a system described in a Hilbert space of dimension N=N-1...N-p, where the numbers N-i are prime, the reconstruction is accomplished with (N-1+1)...(N-p+1) factorable (local) von Neumann measurements. For the special case where the dimension is a power of a prime, the reconstruction can be performed in a much more efficient way using N+1 complementary measurements. If the system is composed of a number of smaller subsystems, these measurements will then in general be nonseparable.
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| 7. |
- Baev, A., et al.
(författare)
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Doppler interference in dissociative resonant photoemission
- 2002
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Ingår i: Physical Review A. Atomic, Molecular, and Optical Physics. - 1050-2947 .- 1094-1622. ; 66:2
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Tidskriftsartikel (refereegranskat)abstract
- Resonant photoemission involving dissociative core excited states has been the subject of a great number of experimental and theoretical investigations in recent time. The resonant decay of such dissociating systems has been shown to lead to semiatomic Auger electron emission spectra, with particular angular behavior. In the present paper a detailed theoretical analysis of dissociative resonant photoemission spectra of homonuclear diatomic molecules is presented. The theory addresses both fixed in space and randomly oriented homonuclear molecules and emphasizes the Doppler effect and the role of the interference between channels referring to the Doppler split atomic fragments. It is shown that peaks originating from decay in the atomic fragments can be asymmetric and structured due to the Doppler interference effect. The predicted strong non-Lorentzian behavior of the substructure on the top of the Doppler broadened atomiclike contribution is traced to the interplay between decay channels leading to gerade and ungerade final states. Simulations based on wave-packet theory are compared with experimental data for molecular oxygen. Our numerical simulations of the atomiclike resonance of fixed in space molecules show that the spectral profile is very sensitive to the shape of interatomic potentials of core excited and final states. It is shown that the Doppler effect in the decay spectra depends upon the symmetry of the core excited state.
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| 8. |
- Baev, A., et al.
(författare)
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Geometrical information on core-excited states obtained from interference quenching of vibrational states in resonant x-ray photoemission
- 2003
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Ingår i: Physical Review A. Atomic, Molecular, and Optical Physics. - 1050-2947 .- 1094-1622. ; 67:2
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Tidskriftsartikel (refereegranskat)abstract
- An interference quenching of the m=1 final state vibrational line in the resonant Auger decay of N 1s-->pi(*) core-excited N-2 is observed and analyzed. The intensity ratio between the m=1 and m=0 vibrational levels of the X (2)Sigma(g)(+) final state shows a surprising nonmonotonic variation as a function of frequency detuning, going through a minimum with a complete suppression of m=1. We have developed a simple model which indicates a linear relation between the value of the detuning frequency for this minimum and the equilibrium bond distance of the core-excited state. This implies the possibility of determining the equilibrium bond distances for core-excited states to a high degree of accuracy. Simultaneously with the simple model we present a strict theory of the studied effect. This strict theory allows us to explore the accuracy of determining the bond length of the core-excited state from resonant Auger spectra. We obtain a weak influence of the core-hole lifetime on the determined bond length, whereas the number of intermediate vibrational states accounted for in the numerical simulations seems to be quite important.
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| 9. |
- Bengtsson, Ingemar, et al.
(författare)
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How to mix a density matrix
- 2003
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Ingår i: Physical Review A. - 1050-2947. ; 67, s. 012107-
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Tidskriftsartikel (refereegranskat)
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| 10. |
- Bergkvist, Sara, et al.
(författare)
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Local-density approximation for confined bosons in an optical lattice
- 2004
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Ingår i: Physical Review A. Atomic, Molecular, and Optical Physics. - 1050-2947 .- 1094-1622. ; 70, s. 053601-1-053601-7
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Tidskriftsartikel (refereegranskat)abstract
- We investigate local and global properties of the one-dimensional Bose-Hubbard model with an external confining potential, describing an atomic condensate in an optical lattice. Using quantum Monte Carlo techniques we demonstrate that a local-density approximation, which relates the unconfined and the confined model, yields quantitatively correct results in most of the interesting parameter range. We also examine claims of universal behavior in the confined system, and demonstrate the origin of a previously calculated fine structure in the experimentally accessible momentum distribution.
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