| 1. |
- Svanberg, Sune, et al.
(författare)
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Applications of terawatt lasers
- 1994
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Ingår i: LASER SPECTROSCOPY - XITH INTERNATIONAL CONFERENCE. - : AIP. - 1551-7616 .- 0094-243X. - 1563962624 ; :290, s. 264-269
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Konferensbidrag (refereegranskat)
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| 2. |
- Bengtsson, G. J, et al.
(författare)
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Radiative-lifetime and Lande-factor Measurements of the Se-i 4p(3)5s (5)s(2) Level Using Pulsed Laser Spectroscopy
- 1992
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Ingår i: Journal de Physique II. - : EDP Sciences. - 1155-4312 .- 1286-4870. ; 2:4, s. 773-779
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Tidskriftsartikel (refereegranskat)abstract
- First laser spectroscopic investigations on atomic selenium are reported. Natural selenium was thermally dissociated in a quartz resonance cell keeping the background pressure of abundant selenium molecules low by differential heating. The 4p35s5S2 level was excited by frequency-tripled pulsed-dye laser radiation at 207 nm. From time-resolved recordings of the fluorescence decay at 216 nm a natural radiative lifetime of 493(15) ns was determined, while quantum-beat and optical double-resonance measurements in an external magnetic field yielded g(J) = 2.0004(10) for the Lande factor. The results are compared with previous theoretical and experimental data.
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| 3. |
- Erman, P, et al.
(författare)
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Autoionization Widths of the No Rydberg-valence State Complex In the 11-12 Ev Region
- 1995
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Ingår i: Chemical Physics Letters. - : Elsevier BV. - 0009-2614. ; 239:1-3, s. 6-10
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Tidskriftsartikel (refereegranskat)abstract
- The photoion excitation spectra of (NO)-N-14 and (NO)-N-15 have been studied in the 105-112 Mn excitation region using high-order harmonic laser spectroscopy. Utilizing the small bandwidth offered by this technique, the natural widths of prominent lines in this region have been measured. These lines originate from interactions between high-lying Rydberg levels converging to the NO+ electronic ground state and a 'new' NO valence state situated close to the latter state. The present measurements show broad resonances corresponding to a decay time of 20-50 fs. This supports the interpretation that the decay takes place via rapid electronic autoionization.
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| 4. |
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| 5. |
- 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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| 6. |
- 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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| 7. |
- Larsson, Jörgen, et al.
(författare)
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Measurements of excited state lifetimes and oscillator strengths in Pt II
- 1996
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Ingår i: Journal of Physics B: Atomic, Molecular and Optical Physics. - : IOP Publishing. - 0953-4075 .- 1361-6455. ; 29:10, s. 1895-1899
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Tidskriftsartikel (refereegranskat)abstract
- We report on radiative lifetime measurements of short-lived states in singly ionized platinum by excitation with pico-second laser pulses and subsequent time-resolved detection. The upper levels were populated from metastable ion levels in a laser-generated plasma using radiation in the UV/VUV spectral range. The following lifetimes were obtained: tau(5d(8)(F-3(4))6p(1/2), J = 7/2) = 3.9(3) ns, tau(5d(8)(F-3(4))6p(3/2), J = 9/2) = 3.5(3) ns and tau(5d(8)(F-3(3))6p(1/2), J = 5/2) = 2.6(3) ns. By using relative intensities of the lines found in the literature, oscillator strengths were determined.
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| 8. |
- Larsson, Jörgen, et al.
(författare)
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Two-color Time-resolved Spectroscopy of Helium Using High-order Harmonics
- 1995
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Ingår i: Journal of Physics B: Atomic, Molecular and Optical Physics. - : IOP Publishing. - 0953-4075 .- 1361-6455. ; 28:3
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Tidskriftsartikel (refereegranskat)abstract
- The radiative lifetime of the 1s2p(1)P state of helium is measured in a two-colour ionization experiment with a 5% accuracy. The state is excited by the 13th harmonic of a tunable 80 ps laser and ionized by a synchronous ultraviolet laser, with a variable time delay. This experiment demonstrates that the high harmonics generated in a jet of rare gas exposed to an intense laser field provide a tunable short-pulse xuv source ideally suited for pump/probe type of studies and, in particular, short lifetime measurements.
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| 9. |
- Larsson, J., et al.
(författare)
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Two-colour time-resolved spectroscopy of helium using high-order harmonics
- 1995
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Ingår i: Journal of Physics B: Atomic, Molecular and Optical Physics. - : IOP Publishing. - 0953-4075 .- 1361-6455. ; 28:3, s. 53-58
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Tidskriftsartikel (refereegranskat)abstract
- The radiative lifetime of the ls2p1P state of helium is measured in a two-colour ionization experiment with a 5% accuracy. The state is excited by the 13th harmonic of a tunable SO ps laser and ionized by a synchronous ultraviolet laser, with a variable time delay. This experiment demonstrates that the high harmonics generated in a jet of rare gas exposed to an intense laser field provide a tunable short-pulse xuv source ideally suited for pump/probe type of studies and, in particular, short lifetime measurements.
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| 10. |
- L'Huillier, Anne, et al.
(författare)
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High-order Harmonics - A Coherent Source In the Xuv Range
- 1995
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Ingår i: Journal of Nonlinear Optical Physics & Materials. - 0218-1991. ; 4:3, s. 647-665
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Tidskriftsartikel (refereegranskat)abstract
- We review the main results concerning high-order generation processes from the point of view of a potential user of this new source of XUV radiation. The perspectives for optimizing the source, both in efficiency and in spectral range, its characteristics and in particular, its coherence properties, are discussed. Finally, we describe two experiments, which demonstrate the usefulness of the harmonics as a short-pulse, coherent source in the XUV domain.
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| 11. |
- Lundberg, Hans, et al.
(författare)
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Experimental Pd II oscillator strengths and the palladium abundance in the HgMn-type star chi Lupi
- 1996
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Ingår i: Astrophysical Journal. - : American Astronomical Society. - 0004-637X .- 1538-4357. ; 469:1, s. 388-392
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Tidskriftsartikel (refereegranskat)abstract
- Experimental oscillator strengths for 19 ultraviolet lines of Pd II have been derived from measurements of line intensities in calibrated Fourier transform spectra, combined with picosecond-pulse laser measurements of radiative lifetimes. Five of these 19 lines, in addition to other Pd nr lines, are present in Hubble Space Telescope/Goddard High-Resolution Spectrograph echelle spectra of the chemically peculiar HgMn star chi Lupi, yielding a palladium abundance of log (N-Pd) = +5.0, which is 3.3 dex above the solar abundance. Theoretical oscillator strengths have been calculated for all strong ultraviolet transitions associated with the lowest odd-parity configuration of Pd II.
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| 12. |
- Luo, C. Y, et al.
(författare)
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Determination of Radiative Lifetimes of Neutral Bismuth By Time-resolved Uv-vuv Laser Spectroscopy
- 1995
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Ingår i: Physical Review A (Atomic, Molecular and Optical Physics). - 1050-2947. ; 52:3, s. 1936-1941
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Tidskriftsartikel (refereegranskat)abstract
- Time-resolved laser spectroscopy was used to measure natural radiative lifetimes of ten excited states of neutral bismuth. Four levels of the 6p(2)ns (4)p(1/2) sequence (n = 7,8,9,10) and the 6p(2)7s P-4(3/2),(5/2) and 6p(2)nd(2)D(2/3;5/2) (n = 6,7) levels were investigated. The results are compared with previous data when possible. Revised absolute transition probabilities for 26 lines are given. Several levels required vacuum-ultraviolet (vuv) excitation, which was achieved by stimulated anti-Stokes Raman shifting of frequency-tripled dye-laser radiation in high-pressure H-2 gas.
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| 13. |
- Mercer, I, et al.
(författare)
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Spatial mode control of high-order harmonics
- 1996
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Ingår i: Physical Review Letters. - 1079-7114. ; 77:9, s. 1731-1734
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Tidskriftsartikel (refereegranskat)abstract
- We demonstrate that the spatial mode of high-order harmonics can be continuously controlled. The control is achieved by spatially modulating the degree of elliptical polarization of the fundamental field using birefringent optics. A highly sensitive relationship between the efficiency of harmonic generation and the degree of laser elliptical polarization leads to atoms emitting harmonics mainly in regions of linear polarization. The harmonics are emitted as annular beams whose angles of divergence can be continuously varied.
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| 14. |
- Zerne, R, et al.
(författare)
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Determination of Radiative Lifetimes In the 3d(10)4snpp-1(1) Sequence of Neutral Zinc By Time-resolved Vuv Laser Spectroscopy
- 1994
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Ingår i: Zeitschrift für Physik D Atoms, Molecules and Clusters. - 0178-7683. ; 32:3, s. 187-189
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Tidskriftsartikel (refereegranskat)abstract
- Time resolved laser spectroscopy in the VUV spectral region is applied to investigate the (n=5-8) 3d(10) 4snp P-1(1) series of neutral zinc. The natural lifetimes of this series were measured by time-resolved laser-induced fluorescence. We find tau(n=5)=11.7(9) ns, tau(n=6)=80(8) ns, tau(n=7)=179(20) ns and tau(n=8)=356 (35) ns. These results are compared with a theoretical calculation.
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| 15. |
- 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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| 16. |
- Zerne, R, et al.
(författare)
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Lande gJ factor measurements in the 6snd(1),D-3(2) sequences of Yb I
- 1996
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Ingår i: Zeitschrift für Physik D Atoms, Molecules and Clusters. - : Springer Science and Business Media LLC. - 0178-7683 .- 1431-5866. ; 37:3, s. 259-261
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Tidskriftsartikel (refereegranskat)abstract
- The Lande g(J) factors in the 6snd(1,3)D(2) sequences as well as states from the perturbing configurations of neutral Ytterbium have been measured by time-resolved fluorescence spectroscopy. Strong singlet-triplet mixing effects were observed. The g(J) factors were measured using the Zeeman quantum-beat technique following step-wise laser excitation. The experiment provided new data for checking the Multi-channel Quantum Defect Theory (MQDT) used in energy-level and lifetime analysis.
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| 17. |
- Zerne, R, et al.
(författare)
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Oscillator strengths of sulphur 3s(2) 3p(3) 4s S-3(0)-3s(2) 3p(3) 4p P-3 transitions measured by time resolved two-photon laser spectroscopy
- 1997
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Ingår i: Physica Scripta. Topical Issues. - : IOP Publishing. - 0281-1847. ; 56:5, s. 459-461
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Tidskriftsartikel (refereegranskat)abstract
- Oscillator strengths for the three 3s(2)3p(3)4s S-3(1)o-3s(2)3p(3)4p P-3(0,1,2) transitions in neutral sulphur have been determined directly from lifetime measurements. Two-photon UV laser excitation and subsequent fluorescence detection have been used on atoms produced in a thermal sulphur beam or in a laser-driven plasma. A good agreement was found between data obtained in both schemes. The lifetime data obtained, tau(P-3(0)) = 46.1(1.0) ns, tau(P-3(1)) = 46.1(1.0) ns and tau(P-3(2)) = 46.1(1.0) ns are compared with results of theoretical and experimental data from literature. The absorption oscillator strengths derived are f(S-3(1)o-P-3(0)) = 0.120(0.003), f(S-3(1)o-P-3(1)) = 0.360(0.008) and f(S-3(1)o-P-3(2)) = 0.600(0.013), respectively. For the next higher member of the series, 3s(2)3p(3)5p P-3(1,2), a substantially longer Lifetime, 188(13) ns, was obtained.
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| 18. |
- Zerne, R, et al.
(författare)
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Phase-locked high-order harmonic sources
- 1997
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Ingår i: Physical Review Letters. - 1079-7114. ; 79:6, s. 1006-1009
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Tidskriftsartikel (refereegranskat)abstract
- We demonstrate that two harmonic sources generated independently in a xenon gas jet using the same picosecond Nd:YAG laser are locked in phase. The experiment is performed by separating a laser beam into two parallel beams focused at different locations under the nozzle of a gas jet, and therefore producing two independent sources of harmonic radiation, and studying the pattern obtained in the far field when the radiations from these sources interfere. A high and robust fringe visibility is obtained.
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| 19. |
- Zerne, R, et al.
(författare)
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Radiative Lifetimes In Neutral Tellurium Measured By Time-resolved Laser Spectroscopy
- 1994
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Ingår i: Zeitschrift für Physik D Atoms, Molecules and Clusters. - 0178-7683. ; 32:1-2, s. 31-34
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Tidskriftsartikel (refereegranskat)abstract
- Measurements of natural radiative lifetimes in atomic tellurium in the 5 p(3)7p configuration are reported. Two-step laser excitation was applied on tellurium vapour in a cell that was differentially heated and pumped through a capillary. The decay of the fluorescence signal was recorded at different vapour pressures. The following four radiative lifetime values were obtained: 7p P-5(1): 128(11) ns, 7p P-5(2): 99(8) ns, 7p P-3(1): 82(10) ns and 7p P-3(2): 124(8) ns.
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