1. |
- Lynga, C, et al.
(author)
-
High-order harmonic generation in molecular gases
- 1996
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In: Journal of Physics B: Atomic, Molecular and Optical Physics. - : IOP Publishing. - 0953-4075 .- 1361-6455. ; 29:14, s. 3293-3302
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Journal article (peer-reviewed)abstract
- We present an experimental study of harmonic generation in molecular gases, using the fundamental (800 nm) and the second harmonic (400 nm) of a 150 fs titanium - sapphire laser at an intensity of ##IMG## [http://ej.iop.org/images/0953-4075/29/14/032/img1.gif] . We compare the conversion efficiency and the maximum energy obtained in different species: rare gases (Ar, Xe), diatomic molecules ( ##IMG## [http://ej.iop.org/images/0953-4075/29/14/032/img2.gif] , ##IMG## [http://ej.iop.org/images/0953-4075/29/14/032/img3.gif] , ##IMG## [http://ej.iop.org/images/0953-4075/29/14/032/img4.gif] , CO) and polyatomic molecules ( ##IMG## [http://ej.iop.org/images/0953-4075/29/14/032/img5.gif] , ##IMG## [http://ej.iop.org/images/0953-4075/29/14/032/img2.gif] O, ##IMG## [http://ej.iop.org/images/0953-4075/29/14/032/img7.gif] , ##IMG## [http://ej.iop.org/images/0953-4075/29/14/032/img8.gif] , ##IMG## [http://ej.iop.org/images/0953-4075/29/14/032/img9.gif] ). The harmonic spectra from molecular gases are very similar to those obtained in the atomic gases, with a plateau and a cutoff whose location is strongly correlated to the value of the ionization potential. The conversion efficiency is not higher than that of the rare gases.
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2. |
- Balcou, P, et al.
(author)
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Quantum-path analysis and phase matching of high-order harmonic generation and high-order frequency mixing processes in strong laser fields
- 1999
-
In: Journal of Physics B: Atomic, Molecular and Optical Physics. - : IOP Publishing. - 0953-4075 .- 1361-6455. ; 32:12, s. 2973-2989
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Journal article (peer-reviewed)abstract
- We study phase-matching conditions for high-order harmonic generation as well as high-order sum- and difference-frequency mixing processes in strong laser fields, using a graphical approach described in Balcou et al (1997 Phys. Rev. A 55 3204-10). This method is based on the analysis of the different quantum paths that contribute, with different phase properties, to the single-atom response. We propose a simple numerical method to disentangle the quantum paths contributing to the generation process. We present graphical maps of the phase matching around the laser focus, which allow one to predict the geometries that optimize the conversion efficiency of the process considered. The method is applied to the study of sum- and difference-frequency mixing processes. The qualitative predictions of the graphical phase-matching approach are confirmed by numerical propagation calculations.
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3. |
- Delfin, C, et al.
(author)
-
Influence of the medium length on high-order harmonic generation
- 1999
-
In: Journal of Physics B: Atomic, Molecular and Optical Physics. - : IOP Publishing. - 0953-4075 .- 1361-6455. ; 32:22, s. 5397-5409
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Journal article (peer-reviewed)abstract
- We study high-order harmonic generation using a 110 fs Ti:sapphire laser loosely focused into a variable-length gas cell filled with neon or argon at 5 mbar pressure. The harmonic intensity is recorded as a function of the medium length, varying between 2 and 21 mm. Several cases are examined, the 17th and the 29th harmonic in argon, and the 29th and 51st harmonic in neon, at the same intensity 4 x 10(14) W cm(-2). We find that the length which maximizes the harmonic yield varies from 10 mm to more than 20 mm. We discuss the different effects affecting the photon yield of the high-order harmonics.
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4. |
- Gaarde, Mette, et al.
(author)
-
High-order tunable sum and difference frequency mixing in the xuv region
- 1996
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In: Journal of Physics B: Atomic, Molecular and Optical Physics. - : IOP Publishing. - 0953-4075 .- 1361-6455. ; 29:5
-
Journal article (peer-reviewed)abstract
- We present a study of tunable high-order sum and difference frequency mixing in the 7-70 eV range, in xenon, argon and neon. We mix the light from a terawatt, subpicosecond titanium-sapphire laser and that from a tunable optical parametric generator. The radiation generated through mixing processes involves absorption or emission of one or Mo photons from the weak tunable source. The relative strengths of the sum and difference frequency processes depend strongly on the wavelength range of the generated radiation. The sum frequency processes are stronger at low photon energies in xenon, whereas the difference frequency processes dominate at high photon energies, in neon, being almost comparable to harmonic generation.
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5. |
- Gisselbrecht, M., et al.
(author)
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Two-photon double-resonant excitation of the Xe* 5p5 nf′ (J = 2) autoionization states using synchronized laser and synchrotron radiation pulses
- 1998
-
In: Journal of Physics B: Atomic, Molecular and Optical Physics. - : IOP Publishing. - 0953-4075 .- 1361-6455. ; 31:24
-
Journal article (peer-reviewed)abstract
- The technique of synchronization between the pulses of a linear dye laser, synchronously pumped by a mode-locked Ar+ laser, and the synchrotron radiation pulses from the SuperACO storage ring in Orsay (France) has been applied to study the photoionization of the Xe* 5p55d [3/2]1 and Xe* 5p56d [3/2]1 excited states in the energy region between the Xe+ 5p5(2P3/2) and (2P1/2) thresholds. The experimental spectra are dominated by strong transitions to the Xe* 5p5nf′ [5/2]2 autoionization resonances, which are characterized by typical asymmetric Fano-type line profiles. The energy positions of the n = 4, 7-13 resonances have been measured. For the 4f′ [5/2]2 and nf′ [5/2]2 (n = 7-9) resonances, the asymmetry parameter q and the linewidth Γ could be determined upon photoexcitation from the intermediate state 5d [3/2]1 and 6d [3/2]1, respectively. As a general behaviour of the investigated excitations, the oscillator strengths for d → f transitions were found to exceed by far those for the, also dipole-allowed, d → p transitions.
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6. |
- Krassig, B, et al.
(author)
-
High-l satellite states in the threshold photoelectron spectrum of argon
- 1996
-
In: Journal of Physics B: Atomic, Molecular and Optical Physics. - : IOP Publishing. - 0953-4075 .- 1361-6455. ; 29:12
-
Journal article (peer-reviewed)abstract
- An interpretation is given of the threshold photoelectron spectrum of Ar between the P-3 and D-1 double-ionization thresholds. In this region the observed spectrum is less cluttered than below the P-3 thresholds and the interpretation is more straightforward. One of the characteristic features of the spectrum is the excitation to Rydberg orbitals with high angular momentum l in agreement with the Wannier picture as first discussed by Fano in 1974.
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7. |
- Larsson, Jörgen, et al.
(author)
-
Measurements of excited state lifetimes and oscillator strengths in Pt II
- 1996
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In: Journal of Physics B: Atomic, Molecular and Optical Physics. - : IOP Publishing. - 0953-4075 .- 1361-6455. ; 29:10, s. 1895-1899
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Journal article (peer-reviewed)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.
(author)
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Two-color Time-resolved Spectroscopy of Helium Using High-order Harmonics
- 1995
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In: Journal of Physics B: Atomic, Molecular and Optical Physics. - : IOP Publishing. - 0953-4075 .- 1361-6455. ; 28:3
-
Journal article (peer-reviewed)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.
(author)
-
Two-colour time-resolved spectroscopy of helium using high-order harmonics
- 1995
-
In: Journal of Physics B: Atomic, Molecular and Optical Physics. - : IOP Publishing. - 0953-4075 .- 1361-6455. ; 28:3, s. 53-58
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Journal article (peer-reviewed)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. |
- Li, Z. S, et al.
(author)
-
Lifetime measurements in Yb II with time-resolved laser spectroscopy
- 1999
-
In: Journal of Physics B: Atomic, Molecular and Optical Physics. - : IOP Publishing. - 0953-4075 .- 1361-6455. ; 32:7, s. 1731-1737
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Journal article (peer-reviewed)abstract
- Natural radiative lifetimes of 10 levels of singly ionized ytterbium have been measured with time-resolved laser spectroscopy. Free Yb+ ions were produced in a laser-induced plasma. A stimulated Brillouin scattering technique has been used to produce laser pulses as short as 1 ns for the excitation of short-lived Yb+ states. Pseudo-relativistic Hartree-Fock calculations, taking into account the core-polarization effects, have also been performed. A good agreement of the measured and the calculated lifetime values has been achieved.
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11. |
- Sikstrom, C. M, et al.
(author)
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The FERRUM project: experimental lifetimes of highly excited FeII 3d(6)4p levels and transition probabilities
- 1999
-
In: Journal of Physics B: Atomic, Molecular and Optical Physics. - : IOP Publishing. - 0953-4075 .- 1361-6455. ; 32:24, s. 5687-5698
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Journal article (peer-reviewed)abstract
- We report on measurements of radiative lifetimes in singly ionized iron of six 3d(6)4p levels between 61 512 and 64 041 cm(-1),using time resolved laser-induced fluorescence. Absolute oscillator strengths of 18 Fe II lines in the wavelength range from 2350 to 2800 Angstrom have been obtained by measuring branching fractions for the lines from two Fe II levels with a Fourier-transform spectrometer. The uncertainty in the lifetimes is between 8% and 13%, whereas the uncertainty of the f-values varies between 9% and 19%. A comparison with several previously published values is given.
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12. |
- Steingruber, J, et al.
(author)
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Prepulse dependence of X-ray emission from plasmas created by IR femtosecond laser pulses on solids
- 1996
-
In: Journal of Physics B: Atomic, Molecular and Optical Physics. - : IOP Publishing. - 0953-4075 .- 1361-6455. ; 29:2
-
Journal article (peer-reviewed)abstract
- We report a strong prepulse dependence of the emission of X-rays from plasmas created by 150 fs Ti:sapphire laser pulses on solids. The laser pulses were focused onto plane samples of aluminium and vanadium with a main pulse power density of about 2.5 x 10(16) W cm(-2). By splitting off a portion of the main pulse we were able to generate a prepulse whose delay and intensity were variable relative to the main pulse. With no prepulse, very weak X-ray radiation from Al9+ and Al10+ was observed, whereas a prepulse to main pulse ratio of more than 0.1% and the prepulse preceding the main pulse by more than 2 ns produced up to 50 times stronger X-ray output.
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13. |
- Bürgers, Andre, et al.
(author)
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The interelectronic angle in doubly excited states and the quality of approximate quantum numbers
- 1998
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In: Journal of Physics B: Atomic, Molecular and Optical Physics. - Washington D.C. : Institute of Physics. - 0953-4075 .- 1361-6455. ; 31, s. 3181-3198
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Journal article (peer-reviewed)abstract
- We present complex scaling calculations of the cosine of the interelectronic angle in doubly excited states of helium below the N = 4 threshold. Since it is directly connected to one of the approximate quantum numbers commonly used to classify doubly excited states, an analysis of this expectation value will give information about the quality of this quantum number. Deviations from the predicted value already occur in the lowest manifold of resonances and are interpreted as a mixture of different basis states. This assertion is tested by a direct doubly excited symmetry basis expansion. Two types of mixing are observed; mixing of basis states to form Rydberg series and mixing of Rydberg series converging to the same threshold. As a possible origin of the basis state mixing which affects the Rydberg series as a whole, avoided crossings in the variation of the resonance energies with respect to the nuclear charge Z are discussed. Mixing between Rydberg series is due to close degeneracies in the resonance energies and connected with avoided crossings in the quantum defect. Both types can easily be distinguished by regarding real and imaginary parts of the complex expectation value
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14. |
- Kato, Takako, et al.
(author)
-
Observations and modelling of line intensity ratios of OV multiplet line
- 1996
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In: Journal of Physics B. - : IOP Publishing. - 0953-4075 .- 1361-6455. ; 29:18, s. 4241-4253
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Journal article (peer-reviewed)abstract
- Line intensity ratios of OV multiplet lines for the 2s3s(3)S(1)-2s3p(3)P(j) (J = 2,1,0) transitions are studied using a collisional radiative model and the results-are compared with measurements from the reversed field pinch experiments Extrap T1 and T2 at KTH. The measured line intensity ratios deviate from the predictions of the model and the possible causes for the discrepancy are discussed with regard to errors in rate coefficients and non-quasi-steady state.
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15. |
- Saenz, Alejandro, et al.
(author)
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The first Born approximation and absolute scattering cross sections
- 1996
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In: Journal of Physics B. - : IOP Publishing. - 0953-4075 .- 1361-6455. ; 29:1, s. 97-113
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Journal article (peer-reviewed)abstract
- The problem of bringing experimental electron-scattering cross sections to the absolute scale using the so-called Lassettre theorem is addressed. Experimental data that have been measured by electron-scattering experiments for different incident energies (in the range of 100 to 600 eV) and have been normalized on the basis of this theorem are compared with absolute cross sections that have been calculated within the first Born approximation by means of the complex-scaling method. The agreement is not found to be satisfactory even for the smallest values of momentum transfer. This, however, is a contradiction to Lassettre's theorem. A new normalization procedure for the experimental data is suggested that has yielded good agreement between the present calculated and the measured data even for a comparatively large range of momentum transfer. This indicates an extended range of validity of the first Born approximation.
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16. |
- Öhrwall, G, et al.
(author)
-
Synchrotron radiation excited photoelectron spectrum of H2(+) with rotational resolution
- 1999
-
In: J. Phys. B: At. Mol. Opt. Phys. - : IOP Publishing. - 0953-4075. ; 32:3, s. L51-L56
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Journal article (peer-reviewed)abstract
- The rotational branching ratio in the photoelectron spectrum of H-2(+) has been investigated using synchrotron radiation. At the photon energy hv = 27 eV, the S (Delta N = 2) branch has a considerably higher relative intensity than when excited with He I (lambda=584 Å, hv=21.218 eV) or with Ne I (lambda=736 Å, hv=16.848) radiation.
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17. |
- Salieres, P, et al.
(author)
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Angular distributions of high-order harmonics generated by a femtosecond laser
- 1996
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In: Journal of Physics B: Atomic, Molecular and Optical Physics. - : IOP Publishing. - 0953-4075. ; 29:20, s. 4771-4786
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Journal article (peer-reviewed)abstract
- We present a systematic study of the angular distributions of high-order harmonics generated with a femtosecond Cr:LiSrAlF6 laser. We investigate the influence of different parameters, namely laser intensity, nonlinear order, nature of the gas and position of the laser focus relative to the generating medium. We show that when the laser is focused before the atomic medium, harmonics with regular spatial profiles can be generated with reasonable conversion efficiency. Their divergence does not depend directly on the nonlinear order, the intensity or even the nature of the generating gas, but rather on the region of the spectrum the considered harmonic belongs to, which is determined by the combination of the three preceding elements. When the focus is drawn closer to the medium, the distributions get increasingly distorted, becoming annular with a significant divergence for a focus right into-or after-the jet. We perform numerical simulations of the angular distributions. The simulated profiles reproduce remarkably well the experimental trends and are thus used to interpret them.
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18. |
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19. |
- AKSELA, H, et al.
(author)
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PARTIAL AUGER DECAY-RATES OF CORE-IONIZED MOLECULAR-STATES IN HCL AND DCL
- 1995
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In: JOURNAL OF PHYSICS B-ATOMIC MOLECULAR AND OPTICAL PHYSICS. - : IOP PUBLISHING LTD. - 0953-4075. ; 28:19, s. 4259-4268
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Journal article (other academic/artistic)abstract
- The Cl 2p ionization and the subsequent 2p(-1) --> 2 pi(-2) Auger decay in HCl and DCl molecules have been studied using synchrotron radiation. The Anger spectra have been decomposed and assigned to the transitions from the (2) Pi(1/2), (2) Sigma(1/2) and
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20. |
- Aksela, H, et al.
(author)
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The character of the Xe 4p -> nl resonances studied with the aid of their Auger decay
- 1998
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In: JOURNAL OF PHYSICS B-ATOMIC MOLECULAR AND OPTICAL PHYSICS. - : IOP PUBLISHING LTD. - 0953-4075. ; 31:24, s. 5337-5346
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Journal article (other academic/artistic)abstract
- Theoretical predictions for the Xe 4p --> nl photoexcitation are shown to depend strongly on the gauge and wavefunctions used in calculations. In order to test the theory, the resonant Auger decay of the Xe 4p(-1)nl states has been measured with high phot
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21. |
- Edvardsson, D, et al.
(author)
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A photoabsorption, photodissociation and photoelectron spectroscopy study of NH3 and ND3
- 1999
-
In: JOURNAL OF PHYSICS B-ATOMIC MOLECULAR AND OPTICAL PHYSICS. - : IOP PUBLISHING LTD. - 0953-4075. ; 32:11, s. 2583-2609
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Journal article (other academic/artistic)abstract
- The absolute photoabsorption, photoionization and photodissociation cross sections and the photoionization quantum efficiency of ammonia and deuterated ammonia have been measured from the ionization threshold to 25 eV using a double ion chamber and monoch
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22. |
- Hemmers, O, et al.
(author)
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Beyond the dipole approximation: angular-distribution effects in valence photoemission
- 1997
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In: Journal of Physics B: Atomic, Molecular and Optical Physics. - 0953-4075. ; 30:21, s. L727-L733
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Journal article (peer-reviewed)abstract
- Angular distributions of valence photoelectrons showing effects due to highermultipole photon interactions have been measured for the first time. Neon 2s and 2p photoemission exhibits effects beyond the dipole approximation throughout the 250 to 1200 eV photon-energy range studied. The results suggest that any photoemission experiment, on any sample, can be affected at relatively low photon energies, pointing to a general need for caution in interpreting angle-resolved-photoemission measurements.
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23. |
- Holland, DMP, et al.
(author)
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An experimental and theoretical study of the valence shell photoelectron spectrum of butadiene
- 1996
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In: JOURNAL OF PHYSICS B-ATOMIC MOLECULAR AND OPTICAL PHYSICS. - : IOP PUBLISHING LTD. - 0953-4075. ; 29:14, s. 3091-3107
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Journal article (other academic/artistic)abstract
- The valence shell photoelectron spectrum of butadiene has been studied using He I, Hen and synchrotron radiation. In addition to the main bands associated with the single-hole states, complex satellite structure due to many-electron effects has been obser
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24. |
- Lundqvist, M, et al.
(author)
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Doppler-free kinetic energy release spectrum of N-2(2+)
- 1996
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In: JOURNAL OF PHYSICS B-ATOMIC MOLECULAR AND OPTICAL PHYSICS. - 0953-4075. ; 29:8, s. 1489-1499
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Journal article (other academic/artistic)abstract
- A Doppler-free kinetic energy release spectrum of N-2(2+) has been recorded using a coincident time-of-flight technique, resolving vibrational structure in the optically active A (1) Pi(u), D (3) Pi(g) and D (1) Sigma(u)(+) electronic states. A comparison
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25. |
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26. |
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27. |
- Ohrwall, G, et al.
(author)
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Inner-valence states of CO+: comparison of photoelectron and resonant Auger spectra
- 1999
-
In: JOURNAL OF PHYSICS B-ATOMIC MOLECULAR AND OPTICAL PHYSICS. - : IOP PUBLISHING LTD. - 0953-4075. ; 32:2, s. 463-473
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Journal article (other academic/artistic)abstract
- We have recorded very-high-resolution photoelectron spectra of the inner-valence structure of CO+, excited with synchrotron radiation, and have resolved fine structure never previously observed. Recently presented resonant Anger decay spectra (Sundin et a
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28. |
- SAIRANEN, OP, et al.
(author)
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THE RESONANCE AUGER DECAY OF THE XE 4D(3/2,5/2)(-1)NP, N=7,8 STATES STUDIED BY HIGH-RESOLUTION EXPERIMENT
- 1995
-
In: JOURNAL OF PHYSICS B-ATOMIC MOLECULAR AND OPTICAL PHYSICS. - : IOP PUBLISHING LTD. - 0953-4075. ; 28:20, s. 4509-4528
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Journal article (other academic/artistic)abstract
- The de-excitation of the resonantly excited Xe 4d(3/2,5/27p)(-1) and 4d(3/2,5/2)(-1)8p states is studied with very high photon and electron energy resolution using the new Finnish beamline at MAX-laboratory, Lund, Sweden. The fine structure of the spectra
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29. |
- Stolte, W.C., et al.
(author)
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The K-shell Auger decay of atomic oxygen
- 1997
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In: Journal of Physics B: Atomic, Molecular and Optical Physics. - 0953-4075. ; 30:20, s. 4489-4497
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Journal article (peer-reviewed)abstract
- Relative photoionization cross sections for O+ and O2+ produced by the Auger decay of a 1s hole in atomic oxygen were measured by using synchrotron radiation between 525 and 553 eV. Energies and quantum defects of the members of the two Rydberg series converging to [1s]2s22p4(4P) and [1s]2s22p4(2P) ionization thresholds were determined. In addition, the 2P and 4P ionization thresholds were calculated from the two Rydberg series. The 182 meV resolution of the monochromator allowed a detailed study over both thresholds revealing evidence for post-collision interaction and allowing a comparison of the ionization continuum above both 2P and 4P thresholds with that of the ionization continuum above the Ar L2 and L3 edges. This comparison indicates that the lifetimes of the Ar(2p) and O(1s) hole states are approximately the same.
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30. |
- Sundin, S, et al.
(author)
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Auger decay of core-excited higher Rydberg states of carbon monoxide
- 1997
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In: JOURNAL OF PHYSICS B-ATOMIC MOLECULAR AND OPTICAL PHYSICS. - : IOP PUBLISHING LTD. - 0953-4075. ; 30:19, s. 4267-4278
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Journal article (other academic/artistic)abstract
- The de-excitation of higher core-excited C 1s(-1)np Rydberg states of carbon monoxide has been studied. It is found that already with a main quantum number of 4 or higher, Rydberg states of p-symmetry can be successfully treated within the single-particle
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31. |
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32. |
- Wang, M, et al.
(author)
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Wavelengths and energy levels of potassium-like Mn VII
- 1997
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In: JOURNAL OF PHYSICS B-ATOMIC MOLECULAR AND OPTICAL PHYSICS. - 0953-4075. ; 30:19, s. 4175-4181
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Journal article (peer-reviewed)abstract
- Photon spectroscopy of potassium-like Mn VII in the 15-200 nm wavelength region is reported following observations involving collision-based spectroscopy and laser plasma spectroscopy. Nineteen transitions from different excited states in Mn VII are ident
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33. |
- Wang, M, et al.
(author)
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Wavelengths and energy levels of potassium-like Ni x
- 1999
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In: JOURNAL OF PHYSICS B-ATOMIC MOLECULAR AND OPTICAL PHYSICS. - 0953-4075. ; 32:22, s. 5299-5309
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Journal article (peer-reviewed)abstract
- An analysis of potassium-like Ni x in the 15-170 nm wavelength region is reported following observations involving collision-based spectroscopy and laser plasma spectroscopy. Ferry five transitions from different excited states in Ni x are identified. Twe
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34. |
- Wehlitz, R, et al.
(author)
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Photon energy dependence of ionization-excitation in helium at medium energies
- 1997
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In: Journal of Physics B: Atomic, Molecular and Optical Physics. - 0953-4075. ; 30:2, s. L51-L58
-
Journal article (peer-reviewed)abstract
- We have measured the photoionization-excitation-to-photoionization ratio for He(+)nl (n = 2-6) at several photon energies from 90 to 900 eV. By extrapolating these values we could determine the asymptotic high-energy ratios for He(+)nl (n = 2-5) which agree with theoretical predictions. We show that the satellite-to-main-line ratios are consistent with experimental double-to-single photoionization ratios and agree well with recent measurements.
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