| 1. |
- Blagoev, KB, et al.
(author)
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Radiative lifetimes of Zn I, II excited states
- 2004
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In: Physica Scripta. - 0031-8949. ; 69:6, s. 433-440
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Journal article (peer-reviewed)abstract
- Radiative lifetimes of excited states of Zn I (3d(10)4sns S-3(1), n = 6-8; 3d(10) 4snd D-3, n = 4-7) and Zn II (3d(10) 4p P-2(1/2.3/2), 4d D-2(3/2,5/2), 3d(10)5S S-2(1/2)) have been measured using a time-resolved laser-induced fluorescence technique. Single- or two-step excitation of atoms and ions produced by laser ablation was employed. The experimental radiative lifetimes have been compared with theoretical results obtained within a multiconfigurational relativistic Hartree-Fock approach taking core-polarization effects into account.
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| 2. |
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| 3. |
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| 4. |
- Herrlin, K, et al.
(author)
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Generation of X-rays For Medical Imaging By High-power Lasers - Preliminary-results
- 1993
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In: Radiology. - 1527-1315. ; 189:1, s. 65-68
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Journal article (peer-reviewed)abstract
- PURPOSE: To evaluate the use of x-ray imaging performed with a high-power laser system in biologic and medical studies. MATERIALS AND METHODS: A compact terawatt laser system based on chirped pulse amplification in titanium-doped sapphire was used. X rays were generated by irradiating a high-atomic-number target (tantalum). RESULTS: When photons with an energy below 10 keV were removed with use of 3 mm of aluminum, the half-value layer in aluminum for the remaining x rays was approximately 10 mm. The x-ray source allowed performance of biologic magnification radiography. Star-pattern tests indicated an equivalent focal spot size of less than 60 mum. Exposures of a single pulse could be obtained. The duration of a single x-ray pulse was estimated to be of the order of picoseconds. CONCLUSION. With use of subpicosecond laser pulses, x-ray generation can occur with a smaller equivalent focal spot size than with conventional x-ray sources.
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| 5. |
- Hunsche, S, et al.
(author)
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Ionization and fragmentation of C-60 via multiphoton-multiplasmon excitation
- 1996
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In: Physical Review Letters. - 1079-7114. ; 77:10, s. 1966-1969
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Journal article (peer-reviewed)abstract
- We study the intensity dependence of ionization and fragmentation of buckminsterfullerene (C-60) in strong laser fields. Our data provide strong evidence that at intensities less than or similar to 10(14) W/cm(2) these processes occur predominantly via multiphoton excitation of the 20 eV plasmon resonance of C-60 At least two plasmons have to be created to initiate fragmentation or multiple ionization.
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| 6. |
- Jiang, Z. K, et al.
(author)
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Investigation of Shifts and Interaction of Signals In High-contrast Transmission Spectroscopy
- 1991
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In: Zeitschrift für Physik D Atoms, Molecules and Clusters. - 0178-7683. ; 21:4, s. 315-322
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Journal article (peer-reviewed)abstract
- In the recently introduced high-contrast transmission version of saturated absorption laser spectroscopy, narrow signals are obtained from dense atomic samples subject to strong pumping. A study of possible systematic shifts of the signals in this domain of rather extreme experimental conditions was performed in order to assess the validity of spectroscopic data obtained with this technique. Certain signal components were found to be slightly shifted while others were not. Further, a theoretical study of the behaviour of overlapping signals in the high-contrast regime is presented. In particular, the question of whether structures buried under the natural linewidth could be resolved is addressed.
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| 7. |
- Johansson, S. G, et al.
(author)
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Comparison of New Experimental and Astrophysical F-values For Some Ru-ii Lines, Observed In Hst Spectra of Chi-lupi
- 1994
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In: Astrophysical Journal. - : American Astronomical Society. - 0004-637X .- 1538-4357. ; 421:2, s. 809-815
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Journal article (peer-reviewed)abstract
- We report on experimental absolute oscillator strengths for 18 UV lines of Ru II, obtained by combining laser-induced fluorescence measurements of radiative lifetimes and branching fractions from line intensities in a calibrated Fourier-transform spectrum. HST/GHRS observations of the spectrum of the sharp-lined B star chi Lupi contain six of these lines, for which ''astrophysical'' relative f-values have been determined. The agreement is within 0.10 dex for a Ru abundance of log N(Ru)/N(H) = -7.90, which is 2.3 dex above the solar abundance.
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| 8. |
- Jönsson, G., et al.
(author)
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Natural radiative lifetimes in the 3 sns 1S0 and 3 snd 1D2 sequences of magnesium
- 1984
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In: Physical Review A. ; A30:5, s. 2429-2432
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Journal article (peer-reviewed)abstract
- Natural radiative lifetimes have been determined in the determined in the 3 sns 1S0 (n=4-15) and the 3 snd 1D2 (n=3-15) sequences of Mg I employing a pulsed-laser system. The radiative lifetimes in the 1S0 sequence and of the higher members in the 1D2 sequence are unperturbed and scale as (n*)2.6 (where n* is the effective principal quantum number), while the lifetimes of the lower members in the 1D2 sequence are perturbed by the doubly excited 3p2 configuration. The measured lifetimes are compared with available theoretical calculations, and a very good agreement is obtained.
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| 9. |
- Kröll, Stefan, et al.
(author)
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Time-resolved laser spectroscopy on high-lying states in neutral oxygen
- 1985
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In: Physical Review Letters. - 1079-7114. ; 55:3, s. 284-287
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Journal article (peer-reviewed)abstract
- Radiative lifetimes have been measured for five triplet states of atomic oxygen. The oxygen atoms were generated by photodissociation of NO2 and the investigated states were populated through a two-step process involving a two-photon excitation to the lowest excited triplet state of even parity, 2p33p 3P, followed by a one-photon excitation to the investigated state. A similar scheme is applicable to the study of excited states in many light atoms.
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| 10. |
- Larsson, Jörgen, et al.
(author)
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Determination of Radiative Lifetimes In the 3snp(1)p(1) Sequence of Mg-i Using Time-resolved Vuv Laser Spectroscopy
- 1993
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In: Zeitschrift für Physik D Atoms, Molecules and Clusters. - 0178-7683. ; 27:4, s. 329-331
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Journal article (peer-reviewed)abstract
- The radiative lifetimes of the states in the (n=5-8) 3snp P-1(1) sequence of neutral magnesium were investigated using time-resolved laser-induced fluorescence. Excitation from the 3s2 S-1(0), ground state was performed using VUV radiation, which was produced by resonant sum-difference frequency mixing in a krypton gas cell. We find tau(n=5): 54(3) ns, tau(n=6): 140(10) ns, tau(n=7): 290(20) ns, tau(n=8): 475(40) ns. These results were found to be in fair agreement with a Multi Configuration Hartree-Fock (MCHF) calculation.
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