| 1. |
- Sanchez-Gonzalez, A., et al.
(author)
-
Auger electron and photoabsorption spectra of glycine in the vicinity of the oxygen K-edge measured with an X-FEL
- 2015
-
In: Journal of Physics B-Atomic Molecular and Optical Physics. - : IOP Publishing. - 0953-4075 .- 1361-6455. ; 48:23
-
Journal article (peer-reviewed)abstract
- We report the first measurement of the near oxygen K-edge auger spectrum of the glycine molecule. Our work employed an x-ray free electron laser as the photon source operated with input photon energies tunable between 527 and 547 eV. Complete electron spectra were recorded at each photon energy in the tuning range, revealing resonant and non-resonant auger structures. Finally ab initio theoretical predictions are compared with the measured above the edge auger spectrum and an assignment of auger decay channels is performed.
|
|
| 2. |
- Zhaunerchyk, Vitali, et al.
(author)
-
Disentangling formation of multiple-core holes in aminophenol molecules exposed to bright X-FEL radiation
- 2015
-
In: Journal of Physics B. - : IOP Publishing. - 0953-4075 .- 1361-6455. ; 48:24
-
Journal article (peer-reviewed)abstract
- Competing multi-photon ionization processes, some leading to the formation of double core hole states, have been examined in 4-aminophenol. The experiments used the linac coherent light source (LCLS) x-ray free electron laser, in combination with a time-of-flight magnetic bottle electron spectrometer and the correlation analysis method of covariance mapping. The results imply that 4-aminophenol molecules exposed to the focused x-ray pulses of the LCLS sequentially absorb more than two x-ray photons, resulting in the formation of multiple core holes as well as in the sequential removal of photoelectrons and Auger electrons (so-called PAPA sequences).
|
|
| 3. |
- Mucke, Melanie, et al.
(author)
-
Covariance mapping of two-photon double core hole states in C2H2 and C2H6 produced by an x-ray free electron laser
- 2015
-
In: New Journal of Physics. - : IOP Publishing. - 1367-2630. ; 17
-
Journal article (peer-reviewed)abstract
- Few-photon ionization and relaxation processes in acetylene (C2H2) and ethane (C2H6) were investigated at the linac coherent light source x-ray free electron laser (FEL) at SLAC, Stanford using a highly efficient multi-particle correlation spectroscopy technique based on a magnetic bottle. The analysis method of covariance mapping has been applied and enhanced, allowing us to identify electron pairs associated with double core hole (DCH) production and competing multiple ionization processes including Auger decay sequences. The experimental technique and the analysis procedure are discussed in the light of earlier investigations of DCH studies carried out at the same FEL and at third generation synchrotron radiation sources. In particular, we demonstrate the capability of the covariance mapping technique to disentangle the formation of molecular DCH states which is barely feasible with conventional electron spectroscopy methods.
|
|
| 4. |
- Murphy, B. F., et al.
(author)
-
Femtosecond X-ray-induced explosion of C-60 at extreme intensity
- 2014
-
In: Nature Communications. - : Springer Science and Business Media LLC. - 2041-1723. ; 5
-
Journal article (peer-reviewed)abstract
- Understanding molecular femtosecond dynamics under intense X-ray exposure is critical to progress in biomolecular imaging and matter under extreme conditions. Imaging viruses and proteins at an atomic spatial scale and on the time scale of atomic motion requires rigorous, quantitative understanding of dynamical effects of intense X-ray exposure. Here we present an experimental and theoretical study of C-60 molecules interacting with intense X-ray pulses from a free-electron laser, revealing the influence of processes not previously reported. Our work illustrates the successful use of classical mechanics to describe all moving particles in C-60, an approach that scales well to larger systems, for example, biomolecules. Comparisons of the model with experimental data on C-60 ion fragmentation show excellent agreement under a variety of laser conditions. The results indicate that this modelling is applicable for X-ray interactions with any extended system, even at higher X-ray dose rates expected with future light sources.
|
|
| 5. |
- Eland, John H. D., 1941, et al.
(author)
-
Dissociation of multiply charged ICN by Coulomb explosion
- 2016
-
In: Journal of Chemical Physics. - : AIP Publishing. - 0021-9606 .- 1089-7690. ; 145:7
-
Journal article (peer-reviewed)abstract
- The fragmentations of iodine cyanide ions created with 2 to 8 positive charges by photoionization from inner shells with binding energies from 59 eV (I 4d) to ca. 900 eV (I 3p) have been examined by multi-electron and multi-ion coincidence spectroscopy with velocity map imaging ion capability. The charge distributions produced by hole formation in each shell are characterised and systematic effects of the number of charges and of initial charge localisation are found. Published by AIP Publishing.
|
|
| 6. |
- Feifel, Raimund, et al.
(author)
-
Cationic double K-hole pre-edge states of CS2 and SF6
- 2017
-
In: Scientific Reports. - : Springer Science and Business Media LLC. - 2045-2322. ; 7
-
Journal article (peer-reviewed)abstract
- Recent advances in X-ray instrumentation have made it possible to measure the spectra of an essentially unexplored class of electronic states associated with double inner-shell vacancies. Using the technique of single electron spectroscopy, spectra of states in CS2 and SF6 with a double hole in the K-shell and one electron exited to a normally unoccupied orbital have been obtained. The spectra are interpreted with the aid of a high-level theoretical model giving excellent agreement with the experiment. The results shed new light on the important distinction between direct and conjugate shake-up in a molecular context. In particular, systematic similarities and di erences between pre-edge states near single core holes investigated in X-ray absorption spectra and the corresponding states near double core holes studied here are brought out.
|
|
| 7. |
- Andersson, Jonas, et al.
(author)
-
Auger decay of 4d inner-shell holes in atomic Hg leading to triple ionization
- 2017
-
In: Physical Review A. - : AMER PHYSICAL SOC. - 2469-9926 .- 2469-9934. ; 96
-
Journal article (peer-reviewed)abstract
- Formation of triply ionized states upon the creation of 4d inner-shell holes in atomic Hg is investigated by using synchrotron radiation of 730 eV photon energy and a versatile multielectron coincidence detection technique in combination with multiconfiguration Dirac-Fock calculations. By carefully selecting Coster-Kronig electrons detected only in coincidence with a 4d photoelectron, the Coster-Kronig spectrum has been extracted and the corresponding branching ratios of the 4d hole have been determined. The results are found to differ from previously established experimental ratios based on electron impact ionization but to agree now better with theory. We also present an Auger cascade analysis of pathways leading to triply ionized states of atomic Hg upon removal of a 4d inner-shell electron.
|
|
| 8. |
- Andersson, Jonas, et al.
(author)
-
Parametrization of energy sharing distributions in direct double photoionization of He
- 2019
-
In: Scientific Reports. - : Springer Science and Business Media LLC. - 2045-2322. ; 9
-
Journal article (peer-reviewed)abstract
- We present experimental results on the characteristic sharing of available excess energy, ranging from 11–221eV, between two electrons in single-photon direct double ionization of He. An effective parametrization of the sharing distributions is presented along with an empirical model that describes the complete shape of the distribution based on a single experimentally determinable parameter. The measured total energy sharing distributions are separated into two distributions representing the shake-off and knock-out parts by simulating the sharing distribution curves expected from a pure wave collapse after a sudden removal of the primary electron. In this way, empirical knock-out distributions are extracted and both the shake-off and knock-out distributions are parametrized. These results suggest a simple method that can be applied to other atomic and molecular systems to experimentally study important aspects of the direct double ionization process.
|
|
| 9. |
- Andersson, Jonas, et al.
(author)
-
Triple ionization of atomic Cd involving 4p(-1) and 4s(-1) inner-shell holes
- 2015
-
In: Physical Review A. - 1050-2947 .- 1094-1622. ; 92:2
-
Journal article (peer-reviewed)abstract
- The triple ionization spectrum of atomic Cd formed upon the removal of a 4p or a 4s inner-shell electron and subsequent Auger decays has been obtained at 200 eV photon energy. By using a versatile multielectron coincidence detection technique based on a magnetic bottle spectrometer in combination with multiconfiguration Dirac-Fock calculations, Auger cascades leading to tricationic final states have been analyzed and final-state configurations have been identified. The most prominent Auger cascades leading to the ground state of Cd3+ have been identified in good agreement with theory.
|
|
| 10. |
- Eland, John H. D., 1941, et al.
(author)
-
Carbon dioxide ion dissociations after inner shell excitation and ionization: The origin of site-specific effects
- 2014
-
In: Journal of Chemical Physics. - : AIP Publishing. - 0021-9606 .- 1089-7690. ; 140:18
-
Journal article (peer-reviewed)abstract
- Multi-coincidence experiments with detection of both electrons and ions from decay of core-excited and core-ionized states of CO2 confirm that O-2(+) is formed specifically in Auger decay from the C1s-pi* and O1s-pi* resonances. Molecular rearrangement occurs by bending in the resonant states, and O-2(+) is produced by both single and double Auger decay. It is suggested that electron capture by C+ after partial dissociation in the doubly ionized core of excited CO2+, formed by shake-up in spectator resonant Auger decay, accounts for high kinetic energy and high internal energy in some C + O-2(+) fragments. (C) 2014 AIP Publishing LLC.
|
|
