| 1. |
- Thomas, T.D., et al.
(författare)
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Photoelectron-recoil-induced rotational excitation of the B 2 state in N2
- 2009
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Ingår i: Physical Review A. Atomic, Molecular, and Optical Physics. - 1050-2947 .- 1094-1622. ; 79:022506
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Tidskriftsartikel (refereegranskat)abstract
- In the photoelectron spectrum of N-2 the apparent ionization energy to form the B (2)Sigma(+)(u) state increases linearly with the photon energy. Rotationally resolved measurements of the fluorescent decay of this state show a linear increase of rotational heating with increasing photon energy. These results are in quantitative agreement with the prediction of the theory of recoil-induced rotational excitation, indicating that the rotational heating that has been observed previously arises primarily from such recoil-induced excitation. Together with other results that have been reported they show that recoil-induced internal excitation is significant in many situations, including near threshold.
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| 2. |
- Feifel, R., et al.
(författare)
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Role of stray light in the formation of high-resolution resonant photoelectron spectra : an experimental and theoretical study of N-2
- 2004
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Ingår i: Journal of Electron Spectroscopy and Related Phenomena. - : Elsevier BV. - 0368-2048 .- 1873-2526. ; 134:1, s. 49-65
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Tidskriftsartikel (refereegranskat)abstract
- We show that the undular stray light, diffusely scattered by the optical system of a synchrotron beamline, can play an important role in the formation of high-resolution resonant photoelectron (RPE) spectra. The influence of the stray light is mediated through the Stokes doubling effect, with the Lorentzian tail of the spectral function being replaced by a more complicated form. This effect is shown to appear in the high-resolution resonant photoelectron spectrum of the N-2 molecule in which the spectral shape of the non-Raman (NR) bands differs qualitatively for the A(2)Pi(u) and X(2)Sigma(g)(+) final states. A particularly large enhancement of the non-Raman Stokes line is observed for the A-state while the picture is inverted for the X-state where the non-Raman band is suppressed. It is shown that the resonant photoemission profile is affected by two qualitatively different detunings, the detuning of the monochromatized line relative to the photoabsorption line and the detuning of the undulator harmonic relative to the same reference line. The experimental data show that the relative intensity of the non-Raman line strongly depends on the tuning of the undulator harmonic with respect to the selected monochromator bandpass, leading to a strong decrease of the Stokes line intensity for certain undulator detunings. A clear red-shift asymmetry for the decrease in the Stokes line intensity is observed when the monochromator line is detuned towards negative photon frequencies, whereas the picture is reverted for the situation of a positively detuned monochromator line. The results show the necessity to control the stray light and to investigate both the Raman and non-Raman contributions to the spectral profiles in order to avoid misinterpretation and in order to make full use of the information available in resonant photoemission spectra of molecules.
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| 3. |
- Travnikova, O., et al.
(författare)
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Ultrafast dissociation of ammonia : Auger Doppler effect and redistribution of the internal energy
- 2022
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Ingår i: Physical Chemistry, Chemical Physics - PCCP. - : Royal Society of Chemistry (RSC). - 1463-9076 .- 1463-9084. ; 24:10, s. 5842-5854
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Tidskriftsartikel (refereegranskat)abstract
- We study vibrationally-resolved resonant Auger (RAS) spectra of ammonia recorded in coincidence with the NH2+ fragment, which is produced in the course of dissociation either in the core-excited 1s−14a11 intermediate state or the first spectator 3a−24a11 final state. Correlation of the NH2+ ion flight times with electron kinetic energies allows directly observing the Auger-Doppler dispersion for each vibrational state of the fragment. The median distribution of the kinetic energy release EKER, derived from the coincidence data, shows three distinct branches as a function of Auger electron kinetic energy Ee: Ee + 1.75EKER = const for the molecular band; EKER = const for the fragment band; and Ee + EKER = const for the region preceding the fragment band. The deviation of the molecular band dispersion from Ee + EKER = const is attributed to the redistribution of the available energy to the dissociation energy and excitation of the internal degrees of freedom in the molecular fragment. We found that for each vibrational line the dispersive behavior of EKERvs. Ee is very sensitive to the instrumental uncertainty in the determination of EKER causing the competition between the Raman (EKER + Ee = const) and Auger (Ee = const) dispersions: increase in the broadening of the finite kinetic energy release resolution leads to a change of the dispersion from the Raman to the Auger one.
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| 4. |
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| 5. |
- Glans, Peter, et al.
(författare)
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Resonant x-ray emission spectroscopy of molecular oxygen
- 1996
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Ingår i: Physical Review Letters. - : AMER INST PHYSICS. - 0031-9007. ; 76:14, s. 2448-2451
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Tidskriftsartikel (refereegranskat)abstract
- Resonant soft x-ray emission spectroscopy has been applied to study the issue of symmetry breaking upon core-hole excitation in molecular oxygen. The results provide direct evidence that the inversion symmetry is not broken in the core-excited states. Furthermore, the experiments themselves demonstrate a new experimental technique of broad applicability for studies of electronic structure and excitation dynamics in free atoms and molecules.
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| 6. |
- Gunnelin, K, et al.
(författare)
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Bond-length-dependent core hole localization observed in simple hydrocarbons
- 1999
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Ingår i: Physical Review Letters. - 0031-9007. ; 83:7, s. 1315-1318
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Tidskriftsartikel (refereegranskat)abstract
- Soft x-ray-emission spectroscopy is applied to measure the amount of dynamic symmetry breaking in core-excited acetylene, ethylene, and ethane. Large variations are observed between the molecules and are rationalized in terms of the different C-C bond lengths: Shorter bond lengths give smaller symmetry breaking. The results also indicate that asymmetric modes are important for all the systems studied, in contradiction to previous assumptions in literature.
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| 7. |
- Hikosaka, Y., et al.
(författare)
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X-ray absorption measured in the resonant Auger scattering mode
- 2008
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Ingår i: Physical Review Letters. - 0031-9007 .- 1079-7114. ; 101:7
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Tidskriftsartikel (refereegranskat)abstract
- We report both experimental and theoretical studies on x-ray absorption measured in the resonant Auger scattering mode of gas phase carbon monoxide near the O1s -> 2 pi region. Both experiment and theory display a crucial difference between the x-ray absorption profiles obtained in the conventional and resonant scattering modes. Lifetime vibrational interference is the main source of the difference. It is demonstrated that such interference, which arises from a coherent excitation to overlapping intermediate levels, ruins the idea for obtaining x-ray absorption spectra in a lifetime broadening free regime.
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| 8. |
- Kikas, A., et al.
(författare)
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Resonant inelastic x-ray scattering at the F 1s photoabsorption edge in LiF : Interplay of excitonic and conduction states, and Stokes' doubling
- 2004
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Ingår i: Physical Review B. Condensed Matter and Materials Physics. - : American Physical Society. - 1098-0121 .- 1550-235X. ; 70:8
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Tidskriftsartikel (refereegranskat)abstract
- The excitation-decay processes at the F 1s photoabsorption edge in LiF crystal are studied using resonant inelastic x-ray scattering spectroscopy. The Raman-type linear dispersion and the narrowing of the x-ray fluorescence peak are observed at resonant excitation. A theoretical model based on the Kramers-Heisenberg formula describes well the main features in fluorescence spectra and allows one to separate the contributions of the exciton and the conduction states in the scattering spectra. At the same time, the role of the shape of the spectral distribution within the incident radiation is emphasized as being critically sensitive to the number, kind, and onset of the spectral features which finally appear in the scattering spectra at a particular incident photon energy, particularly in the subthreshold excitation region.
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| 9. |
- Kimberg, Victor, et al.
(författare)
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Angular properties of band structures in one-dimensional holographic photonic crystals
- 2004
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Ingår i: Journal of Optics. A, Pure and applied optics. - : Institute of Physics Publishing (IOPP). - 1464-4258 .- 1741-3567. ; 6:10, s. 991-996
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Tidskriftsartikel (refereegranskat)abstract
- One-dimensional photonic crystals with continuous distribution of the dielectric constant were fabricated by the use of photopolymer materials and laser holography. The angular dependence of light propagation through the system was studied experimentally and theoretically. It is shown that the Brewster angles for different bands are different, in contrast to the conventional two-layer Bragg reflector with a step-like distribution of the dielectric constant. Comparison of the theory with experimental data allowed us to define the parameters of the hologram-the dielectric contrast and the shrinkage of the structure.
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| 10. |
- Kukk, E, et al.
(författare)
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Raman versus non-Raman behavior in resonant auger spectra of HCl
- 1996
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Ingår i: PHYSICAL REVIEW LETTERS. - : AMER INST PHYSICS. ; 76:17, s. 3100-3103
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- Two different types of Anger processes are shown to constitute the resonant Anger spectra of HCl: one which does and one which does not show Raman narrowing with the decrease of the spectral width of the exciting radiation. An analytical explanation for t
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