| 1. |
- Baev, A., et al.
(författare)
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Geometrical information on core-excited states obtained from interference quenching of vibrational states in resonant x-ray photoemission
- 2003
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Ingår i: Physical Review A. Atomic, Molecular, and Optical Physics. - 1050-2947 .- 1094-1622. ; 67:2
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Tidskriftsartikel (refereegranskat)abstract
- An interference quenching of the m=1 final state vibrational line in the resonant Auger decay of N 1s-->pi(*) core-excited N-2 is observed and analyzed. The intensity ratio between the m=1 and m=0 vibrational levels of the X (2)Sigma(g)(+) final state shows a surprising nonmonotonic variation as a function of frequency detuning, going through a minimum with a complete suppression of m=1. We have developed a simple model which indicates a linear relation between the value of the detuning frequency for this minimum and the equilibrium bond distance of the core-excited state. This implies the possibility of determining the equilibrium bond distances for core-excited states to a high degree of accuracy. Simultaneously with the simple model we present a strict theory of the studied effect. This strict theory allows us to explore the accuracy of determining the bond length of the core-excited state from resonant Auger spectra. We obtain a weak influence of the core-hole lifetime on the determined bond length, whereas the number of intermediate vibrational states accounted for in the numerical simulations seems to be quite important.
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| 2. |
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| 3. |
- Feifel, R., et al.
(författare)
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"Hidden" vibrations in CO : Reinvestigation of resonant Auger decay for the C 1s → π* excitation
- 2002
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Ingår i: Physical Review A - Atomic, Molecular, and Optical Physics. - 1050-2947. ; 65:5 A, s. 527011-527018
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Tidskriftsartikel (refereegranskat)abstract
- The higher vibrational levels of the C 1s→π* excitation in carbon monooxide (CO) were investigated by using resonant Auger electron spectroscopy. The absorption profile of the CO was recorded in the partial electron yield mode. The results showed that the vibrational states were not seen in a total yield absorption spectrum whereas they were shown to be discernable in a partial electron yield spectrum.
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| 4. |
- Feifel, R., et al.
(författare)
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Interference quenching of nu('')=1 vibrational line in resonant photoemission of N-2 : A possibility to obtain geometrical information on the core-excited state
- 2002
-
Ingår i: Physical Review Letters. - 0031-9007 .- 1079-7114. ; 89:10
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Tidskriftsartikel (refereegranskat)abstract
- An interference quenching of the nu=1 vibrational line in the resonant Auger decay of N 1s-->pi(*) core-excited N-2 is observed and analyzed. The intensity ratio between the nu=1 and nu=0 vibrational levels of the X(2)Sigma(g)(+) final state shows a surprising nonmonotonous variation as a function of frequency detuning, going through a minimum with a complete suppression of nu=1. We have developed a simple model which shows a linear relation between the value of the detuning frequency for this minimum and the equilibrium bond distance R-c(0) of the core-excited state. A new way is thus established of determining the equilibrium bond distance for the core-excited state with a precision deltaR(c)(0)<10(-3) Angstrom.
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| 5. |
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| 6. |
- Hjelte, I, et al.
(författare)
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Evidence for ultra-fast dissociation of molecular water from resonant Auger spectroscopy
- 2001
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Ingår i: CHEMICAL PHYSICS LETTERS. - : ELSEVIER SCIENCE BV. - 0009-2614. ; 334:1-3, s. 151-158
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Tidskriftsartikel (refereegranskat)abstract
- We present direct evidence for ultra-fast dissociation of molecular water in connection photo-excitation of the Ols --> 4a(1) resonance. The core-excited H2O molecules are shown to dissociate into core-excited O*H and neutral H on a time scale comparable
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| 7. |
- Hjelte, I., et al.
(författare)
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Evidence for ultra-fast dissociation of molecular water from resonant Auger spectroscopy
- 2001
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Ingår i: Chemical Physics Letters. - 0009-2614. ; 334:1-3, s. 151-158
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Tidskriftsartikel (refereegranskat)abstract
- We present direct evidence for ultra-fast dissociation of molecular water in connection photo-excitation of the O1s→4a1 resonance. The core-excited H2O molecules are shown to dissociate into core-excited O*H and neutral H on a time scale comparable to the core hole lifetime, i.e. a few femtoseconds. This conclusion is based on a resonant Auger study, qualitative arguments and ab initio calculations. 'Hot bands' connected to Auger transitions from vibrationally excited OH fragments are identified, and these exhibit a dynamical behavior which qualitatively follows the change in excess energy.
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| 8. |
- Björneholm, O., et al.
(författare)
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Doppler splitting of in-flight auger decay of dissociating oxygen molecules : The localization of delocalized core holes
- 2000
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Ingår i: Physical Review Letters. - : AMERICAN PHYSICAL SOC. - 0031-9007 .- 1079-7114. ; 84:13, s. 2826-2829
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Tidskriftsartikel (refereegranskat)abstract
- By exploiting the core-excitation-induced dissociation of O-2, we find that the Auger emission exhibits a Doppler-like energy shift. We show this to be a manifestation of localization of the core hole and propose that the problem of core-hole localization versus delocalization in core-hole spectroscopies may be resolved by considering the nature of the measurement.
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| 9. |
- Burmeister, F, et al.
(författare)
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Nonadiabatic effects in photoelectron spectra of HCl and DCl. I. Experiment
- 2002
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Ingår i: Physical Review A (Atomic, Molecular and Optical Physics). - 1050-2947. ; 65:1
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Tidskriftsartikel (refereegranskat)abstract
- The HCl inner-valence photoelectron band at 26 eV binding energy has been recorded at high resolution. Discrete peaks arising from at least two separate vibrational progressions are superimposed on the broad continuum. Fano profiles are visible in one of the progressions. This indicates interference between superimposed electronic states, where weak avoided crossing allows two adiabatic states to couple. In the isotopic DCl molecular spectrum, the discrete lines are less pronounced, due to slower dissociation and therefore less coupling between the continuum and the bound state.
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| 10. |
- Feifel, R., et al.
(författare)
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Generalization of the duration-time concept for interpreting high-resolution resonant photoemission spectra
- 2004
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Ingår i: Physical Review A. Atomic, Molecular, and Optical Physics. - 1050-2947 .- 1094-1622. ; 69:2, s. 022707-
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Tidskriftsartikel (refereegranskat)abstract
- The duration-time concept, vastly successful for interpreting the frequency dependence of resonant radiative and nonradiative x-ray scattering spectra, is tested for fine-scale features that can be obtained with state of the art high-resolution spectroscopy. For that purpose resonant photoelectron (RPE) spectra of the first three outermost singly ionized valence states X (2)Sigma(g)(+), A (2)Pi(u), and B (2)Sigma(u)(+), are measured for selective excitations to different vibrational levels (up to n=13) of the N 1s-->pi(*) photoabsorption resonance in N-2 and for negative photon frequency detuning relative to the adiabatic 0-0 transition of this resonance. It is found that different parts of the RPE spectrum converge to the spectral profile of direct photoionization (fast scattering) for different detunings, and that the RPE profiles are asymmetrical as a function of frequency detuning. The observed asymmetry contradicts the picture based on the simplified notation of a common scattering duration time, but is shown to agree with the here elaborated concept of partial and mean duration times. Results of the measurements and the simulations show that the duration time of the scattering process varies for different final electronic and different final vibrational states. This owes to two physical reasons: one is the competition between the fast vertical and the slow resonant scattering channels and the other is the slowing down of the scattering process near the zeros of the real part of the scattering amplitude.
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