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- Frasinski, L. J, et al.
(författare)
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Multielectron Dissociative Ionization of Co2 In Intense Laser Fields
- 1994
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Ingår i: Journal of Physics B: Atomic, Molecular and Optical Physics. - : IOP Publishing. - 0953-4075 .- 1361-6455. ; 27:6, s. 97-109
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Tidskriftsartikel (refereegranskat)abstract
- The multiphoton ionization of CO2 has been studied using a laser of 794 nm WaVelength and focused intensities in the region of 10(16) W cm-2. The kinetic energy distributions and ion yields obtained using time-of-flight spectroscopy coupled with covariance mapping can be interpreted most simply in terms of charge-symmetric fragmentation, the strongest channel being O2+ + C2+ + O2+. These results are compared with two recent experiments on CO2, one using an intense laser at 248 nm, the other using Si8+ ion projectiles of 3 MeV u-1 energy.
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- Herrlin, K, et al.
(författare)
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Generation of X-rays For Medical Imaging By High-power Lasers - Preliminary-results
- 1993
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Ingår i: Radiology. - 1527-1315. ; 189:1, s. 65-68
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Tidskriftsartikel (refereegranskat)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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- Jiang, Z. K, et al.
(författare)
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Investigation of Shifts and Interaction of Signals In High-contrast Transmission Spectroscopy
- 1991
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Ingår i: Zeitschrift für Physik D Atoms, Molecules and Clusters. - 0178-7683. ; 21:4, s. 315-322
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Tidskriftsartikel (refereegranskat)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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- Johansson, S. G, et al.
(författare)
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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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Ingår i: Astrophysical Journal. - : American Astronomical Society. - 0004-637X .- 1538-4357. ; 421:2, s. 809-815
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Tidskriftsartikel (refereegranskat)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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- Larsson, Jörgen, et al.
(författare)
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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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Ingår i: Zeitschrift für Physik D Atoms, Molecules and Clusters. - 0178-7683. ; 27:4, s. 329-331
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Tidskriftsartikel (refereegranskat)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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