| 1. |
- Beideck, DJ, et al.
(författare)
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Lifetimes of 5d96p and 5d86s6p levels in Hg iii
- 1993
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Ingår i: Physical Review A (Atomic, Molecular and Optical Physics). - 1050-2947. ; 47:2, s. 884-889
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Tidskriftsartikel (refereegranskat)abstract
- Experimental and theoretical studies of lifetimes and transition probabilities for doubly ionized mercury, Hg III, are reported. Such data are currently of great astrophysical interest because observations with the Goddard high resolution spectrograph on board the Hubble space telescope have shown some 5d(9)6s-5d(9)6p transitions of Hg III in the spectrum of the chemically peculiar star chi Lupi. We now report experimental lifetimes for some selected 5d(9)6p and 5d(8)6s6p levels, determined by beam-foil spectroscopy, and compare the results with theoretical transition probabilities based on relativistic multiconfiguration Dirac-Fock calculations.
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| 2. |
- Bengtsson, G. J, et al.
(författare)
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Natural Lifetimes of Excited-states of Neutral Nitrogen Determined By Time-resolved Laser Spectroscopy
- 1992
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Ingår i: Physical Review A (Atomic, Molecular and Optical Physics). - 1050-2947. ; 45:5, s. 2712-2715
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Tidskriftsartikel (refereegranskat)abstract
- Radiative lifetimes were determined for three quartet states of neutral nitrogen, and sequences of Rydberg states were studied using depletion spectroscopy. Free nitrogen atoms were generated by photodissociation of N2O using frequency-tripled dye-laser radiation that was two-photon resonant with the 2p(2)3p 4S or 4D states. Further quartet states were reached by a subsequent single-photon absorption. We obtain tau(2p(2)3p 4D7/2) = 44(2) ns, tau(2p(2)3p 4S3/2) = 26.0(1.5) ns, and tau(2p(2)6s4P5/2) = 41(7) ns.
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| 3. |
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| 4. |
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| 5. |
- 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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| 6. |
- Carlsson, J, et al.
(författare)
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Large Multiconfigurational Hartree-fock Calculations On the Hyperfine-structure Constants of the Li-7 2s 2s and 2p 2p States
- 1992
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Ingår i: Physical Review A (Atomic, Molecular and Optical Physics). - 1050-2947. ; 46:5, s. 2420-2425
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Tidskriftsartikel (refereegranskat)abstract
- Accurate hyperfine-structure parameters for the ground and first excited states of lithium are reported. Hyperfine parameters are calculated from multiconfiguration Hartree-Fock (MCHF) wave functions using a recently written hyperfine-structure program, being a part of the MCHF Atomic Structure Package. Convergence of the hyperfine-structure parameters is studied as the active set of orbitals is increased. The relativistic, finite-nuclear-size, and finite-nuclear-mass-corrected values of the magnetic hyperfine-structure constants of the 2s S-2(1/2) and 2p P-2(1/2,3/2) states of Li-7 were determined to be A1/2=401.70 MHz and A1/2=45.94 MHz, A3/2=3.098 MHz, respectively. The final values are compared with experiments and with the most reliable theoretical values obtained with other methods.
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| 7. |
- 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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| 8. |
- 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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| 9. |
- Glans, Peter, et al.
(författare)
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Determination of the lifetime width of the argon L1-hole state
- 1993
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Ingår i: Physical Review A (Atomic, Molecular, and Optical Physics). - 1050-2947. ; 47:2, s. 1539-1542
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Tidskriftsartikel (refereegranskat)abstract
- The width of the argon 2s level was experimentally obtained from x-ray emission-spectroscopy (2.25+/-0.15 eV) and x-ray photoelectron-spectroscopy (XPS) (2.25+/-0.05 eV) measurements. A theoretical value of 1.85 eV was obtained by a Green's-function calculation. A high-energy satellite located 2.7+/-0.2 eV above the L1-M2,3 x-ray emission transition was confirmed and identified as the 2s(-1)3p-1-->3p-2 double-hole transition. The XPS measurement of the argon 2s ionization energy gave a value of 326.25(5) eV.
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| 10. |
- 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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