| 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. |
- 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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| 3. |
- Jönsson, Per, et al.
(författare)
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Large-scale Multiconfiguration Hartree-fock Calculations of Hyperfine-interaction Constants For Low-lying States In Beryllium, Boron, and Carbon
- 1993
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Ingår i: Physical Review A (Atomic, Molecular and Optical Physics). - 1050-2947. ; 48:6, s. 4113-4123
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Tidskriftsartikel (refereegranskat)abstract
- Multiconfiguration Hartree-Fock (MCHF) calculations of hyperfine constants for the 2s2p 3P states of beryllium and the ground states of boron and carbon are reported. The capacity of a recently developed configuration-interaction program [Froese Fischer and Tong (unpublished); Stathopoulos and Froese Fischer (unpublished)], allowing for large configuration expansions, is explored. Using a systematic active-space MCHF approach, combined with large multireference configuration-interaction calculations, it is shown that hyperfine constants can be calculated very accurately. To reliably account for spin-polarization of the Is and 2s shells in boron and carbon, three-particle effects had to be included in a systematic way. The relativistic, finite-nuclear-size- and finite-nuclear-mass-corrected values of the hyperfine constants are compared with experimental values and with the most accurate theoretical values obtained with other methods.
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| 4. |
- L'Huillier, Anne, et al.
(författare)
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High-order Harmonic-generation Cutoff
- 1993
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Ingår i: Physical Review A (Atomic, Molecular and Optical Physics). - 1050-2947. ; 48:5
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Tidskriftsartikel (refereegranskat)abstract
- We have experimentally determined the harmonic-generation cutoff as a function of the laser intensity in neon using an intense, short-pulse Ti:sapphire laser. The experimental cutoff is lower than that obtained in single-atom calculations. Using a simple quantum-mechanical approach to harmonic generation valid at high intensity, we show that the difference is due to the effect of propagation.
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| 5. |
- Wahlström, Claes-Göran, et al.
(författare)
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High-order Harmonic-generation In Rare-gases With An Intense Short-pulse Laser
- 1993
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Ingår i: Physical Review A (Atomic, Molecular and Optical Physics). - 1050-2947. ; 48:6, s. 4709-4720
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Tidskriftsartikel (refereegranskat)abstract
- We present experimental studies of high-order harmonic generation in the rare gases performed with a short-pulse titanium sapphire laser operating at 794 nm in the 10(14)-10(15) W/cm2 range. The harmonic yields generated in neon and in argon are studied for all orders as a function of the laser intensity. They vary first rather steeply, in the cutoff region, then much more slowly in the plateau region, and, finally, they saturate when the medium gets ionized. The dependence of the high-order harmonic cutoff with the laser intensity in neon and argon is found to be lower than that predicted in single-atom theories. We observe high-order harmonics in argon and xenon (up to the 65th and 45th, respectively) at 10(15) W/cm2, which we attribute to harmonic generation from ions. We also show how the harmonic and fundamental spectra get blueshifted when the medium becomes ionized.
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