| 1. |
- Brage, Tomas, et al.
(författare)
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Effects of Core-valence and Core-core Correlation On the Line-strength of the Resonance Lines In Li-i and Na-i
- 1994
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Ingår i: Physical Review A (Atomic, Molecular and Optical Physics). - 1050-2947. ; 49:3, s. 2181-2184
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Tidskriftsartikel (refereegranskat)abstract
- The resonance lines in Li I and Na I both exhibit a puzzling discrepancy between experiment and accurate ab initio calculations. Only results from a semiempirical method, that in principal neglects core-core correlation, agree with the experiments. The agreement with a multiconfiguration Hartree-Fock calculation, including only core-valence correlation, shows that this might be fortuitous. A method for including some core-core correlation is designed and gives results in excellent agreement with other accurate ab initio methods.
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| 2. |
- Carlsson, J, et al.
(författare)
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Lifetimes and Transition-probabilities of the Boron Atom Calculated With the Active-space Multiconfiguration Hartree-fock Method
- 1994
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Ingår i: Physical Review A (Atomic, Molecular and Optical Physics). - 1050-2947. ; 49:5, s. 3426-3431
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Tidskriftsartikel (refereegranskat)abstract
- Systematic multiconfiguration Hartree-Fock results are presented for the transition probabilities and excited-state lifetimes in the term system of the boron atom. Particularly, the interaction between the 1s(2)2s2p2 configuration and the 1s(2)2s2ns2S and 1s(2)2s2nd2D Rydberg series is considered. Term energies and transition-matrix elements are calculated to convergence using increasing active sets of s, p, d, f, and g orbitals.
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| 3. |
- Gaarde, Mette, et al.
(författare)
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Determination of Radiative Lifetimes of Excited-states In Neutral Gold Using Time-resolved Vacuum-ultraviolet Laser Spectroscopy
- 1994
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Ingår i: Physical Review A (Atomic, Molecular and Optical Physics). - 1050-2947. ; 50:1, s. 209-213
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Tidskriftsartikel (refereegranskat)abstract
- Natural radiative lifetimes of the states in the highly perturbed 5d10np 2P sequence in neutral gold, Au I, for n = 6-9, as well as of four of the perturbing 5d(9)6s6p 2P states, have been measured. This was done by direct excitation from the ground state with short-pulse vacuum-ultraviolet laser light and time-resolved detection of the laser-induced fluorescence. We found the lifetimes to be tau(6p P-2(1/2))=6.2(2) ns, tau(6p P-2(3/2))=4.7(2) ns, tau(7p P-2(1/2))=6.4(7) ns, tau(7p P-2(3/2))=5.3(7) ns, tau(8p P-2(1/2))=63(3) ns, tau(8p P-2(3/2))=24(2) ns, tau(9p P-2(1/2))=28(2) ns, and tau(9p P-2(3/2))=75(4) ns. For the perturbing states (two states of each term have been observed) we found tau(P-2(1/2), 60983.05 cm-1)=17.5(10) ns, tau(P-2(1/2), 62540.65 cm-1)=6.7(7) ns, tau(P-2(3/2), 58826.30 cm-1)=2.1(15) ns, and tau(P-2(3/2), 63005.62 cm-1)=2.7(15) ns. Furthermore, we have investigated the hyperfine structure of the 6p P-2(3/2) State.
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| 4. |
- Jönsson, Per, et al.
(författare)
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Large-scale Multiconfiguration Hartree-fock and Configuration-interaction Calculations of Isotope Shifts and Hyperfine Structures In Boron
- 1994
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Ingår i: Physical Review A (Atomic, Molecular and Optical Physics). - 1050-2947. ; 50:4, s. 3080-3088
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Tidskriftsartikel (refereegranskat)abstract
- A new isotope shift program, part of the multiconfiguration Hartree-Fock (MCHF) atomic structure package, has been written and tested. The program calculates the isotope shift of an atomic level from MCHF or configuration-interaction (CI) wave functions. The program is specially designed to be used with very large CI expansions, for which angular data cannot be stored on disk. To explore the capacity of the program, large-scale isotope shift calculations were performed for the 1s(2)2s(2)2p 2P, 1s(2)2s(2)3s2S, and 1s(2)2s2p2 2D levels in boron. From the isotope shifts of these levels the transition isotope shifts were calculated for the two resonance transitions. The calculated transition isotope shifts are in very good agreement with experimental shifts. As an additional test of the quality of the CI wave functions, the hyperfine structure was calculated for all levels.
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| 5. |
- Karlsson, Hans O
(författare)
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Dynamics of hydrogenic wave packets in electric and magnetic fields
- 1994
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Ingår i: Physical Review A. Atomic, Molecular, and Optical Physics. - 1050-2947 .- 1094-1622. ; 50:5, s. 3787-3792
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Tidskriftsartikel (refereegranskat)abstract
- The survival probability P(t) of hydrogenic wave packets for some choices of strong external electric and magnetic fields is studied. The recursive residue generation method, in combination with complex dilation and a Laguerre basis, is used to calculate the local density of states from which P(t) is computed via a Fourier transform. P(t) is calculated both for a single initial ‖8p0〉 state and for an initial radial hydrogenic wave packet centered around n=15. In the first case only, in principle, a single n manifold is involved in the dynamics, while in the latter case several n manifolds contribute. The different choices of initial states lead to significantly different results. The choice of fields was made in order to exemplify various patterns of behavior. Results similar to those obtained here were found in recent experiments by Broers and co-workers [Phys. Rev. Lett. 71, 344 (1993); Phys. Rev. A 49, 2498 (1994)]. The results presented in this work are quantum-mechanical calculations of hydrogenic wave packets in strong fields that include the effect of finite lifetimes on P(t).
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| 6. |
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| 7. |
- Kurasov, Pavel, et al.
(författare)
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δ' potential arising in exterior complex scaling
- 1994
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Ingår i: Physical Review A (Atomic, Molecular and Optical Physics). - 1050-2947. ; 49:6, s. 5095-5097
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Tidskriftsartikel (refereegranskat)abstract
- In the method of exterior complex scaling the coordinates of the Hamilton operator are scaled by a constant factor starting at a radius R≠0. We show that this procedure induces a singularity in the kinetic-energy term which must be interpreted as the derivative of a δ function.
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| 8. |
- LaVilla, R.E., et al.
(författare)
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Additional features in the 3d-4p x-ray-emission spectrum of Xe
- 1994
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Ingår i: Physical Review A - Atomic, Molecular, and Optical Physics. - 1050-2947. ; 49:3, s. 2185-2187
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Tidskriftsartikel (refereegranskat)abstract
- The high-resolution 3d-4p x-ray-emission spectrum of Xe excited by electron impact was measured. In addition to the prominent peak due to 3d5/2-4p3/2 previously reported, the experimental high-resolution spectrum shows a weak peak, identified as 3d3/2-4P3/2, and satellites. The satellites are tentatively attributed to 3d-1X-1-4p-1X-1 (X = 4s, 4p, and 4d), where the initial doubly ionized states are created by the Auger (Coster-Kronig) decay of the 2p and/or 3p level. The experimental 3d-4p x-ray spectrum is compared with a theoretical spectrum calculated by the ab initio Green's-function method.
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| 9. |
- Zerne, R, et al.
(författare)
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Determination of Radiative Lifetimes In the 3d(10)np(2)p Sequence of Neutral Copper By Time-resolved Vuv Laser-spectroscopy
- 1994
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Ingår i: Physical Review A (Atomic, Molecular and Optical Physics). - 1050-2947. ; 49:1, s. 128-131
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Tidskriftsartikel (refereegranskat)abstract
- Lifetimes in the 3d(10)np(2)P sequence in neutral copper were measured by time-resolved laser spectroscopy. Excitation from the ground state was performed with pulsed laser radiation in the; vuv spectral region, generated by resonant sum-difference four-wave mixing in krypton gas. The lifetimes were evaluated from recorded optical transients. For the np(2)P(J) states we find the following: tau(n = 6, 5 = 3/2) = 5.2(8) ns, tau(6, 1/2) = 25.1(10) ns, tau(7; 3/2) = 15.0(12) ns, tau(7, 1/2) = 4.0(8) ns, tau(8,3/2) = 31(2) ns, tau(8, 1/2) = 15.8(12) us, tau(9, 3/2) = 123(6) ns, and tau(9, 1/2) = 51(6) ns. The data are compared with a recent multiconfiguration Hartree-Fock calculation.
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