| 1. |
- Rohringer, N., et al.
(författare)
-
Stimulated X-Ray Raman Scattering with Free-Electron Laser Sources
- 2016
-
Ingår i: X-Ray Lasers 2014. - Cham : Springer. - 0930-8989. - 9783319195216 - 9783319195209 ; , s. 201-207
-
Bokkapitel (refereegranskat)abstract
- Stimulated electronic x-ray Raman scattering is the building block for several proposed x-ray pump probe techniques, that would allow the study of electron dynamics at unprecedented timescales.We present high spectral resolution data on stimulated electronic x-ray Raman scattering in a gas sample of neon using a self-amplified spontaneous emission x-ray free-electron laser. Despite the limited spectral coherence and broad bandwidth of these sources, high-resolution spectra can be obtained by statistical methods, opening the path to coherent stimulated x-ray Raman spectroscopy. An extension of these ideas to molecules and the results of a recent experiment in CO are discussed.
|
|
| 2. |
- Sanchez-Gonzalez, A., et al.
(författare)
-
Auger electron and photoabsorption spectra of glycine in the vicinity of the oxygen K-edge measured with an X-FEL
- 2015
-
Ingår i: Journal of Physics B-Atomic Molecular and Optical Physics. - : IOP Publishing. - 0953-4075 .- 1361-6455. ; 48:23
-
Tidskriftsartikel (refereegranskat)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.
|
|
| 3. |
- Bolognesi, P., et al.
(författare)
-
A study of the dynamical energy flow in uracil
- 2015
-
Ingår i: Journal of Physics, Conference Series. - : IOP Publishing. - 1742-6588 .- 1742-6596. ; 635
-
Tidskriftsartikel (refereegranskat)abstract
- The time resolved photoionization of C 1s in uracil following excitation of the neutral molecule by 260 nm pulses has been studied at LCLS.
|
|
| 4. |
- Eland, John H. D., 1941, et al.
(författare)
-
Carbon dioxide ion dissociations after inner shell excitation and ionization: The origin of site-specific effects
- 2014
-
Ingår i: Journal of Chemical Physics. - : AIP Publishing. - 0021-9606 .- 1089-7690. ; 140:18
-
Tidskriftsartikel (refereegranskat)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.
|
|
| 5. |
- Eland, John H. D., 1941, et al.
(författare)
-
Direct observation of three-electron collective decay in a resonant Auger process
- 2015
-
Ingår i: New Journal of Physics. - : IOP Publishing. - 1367-2630. ; 17
-
Tidskriftsartikel (refereegranskat)abstract
- Using a multi-electron coincidence technique combined with synchrotron radiation we demonstrate the real existence of the elusive three-electron collective process in resonant Auger decay of Kr. The three-electron process is about 40 times weaker than the competing two-electron processes.
|
|
| 6. |
- Eland, John H. D., et al.
(författare)
-
Homonuclear site-specific photochemistry by an ion-electron multi-coincidence spectroscopy technique
- 2012
-
Ingår i: Chemical Physics Letters. - : Elsevier BV. - 0009-2614 .- 1873-4448. ; 548, s. 90-94
-
Tidskriftsartikel (refereegranskat)abstract
- By combining multi-particle coincidence detection of electrons and ions with ionisation by soft X-ray synchrotron radiation we demonstrate an effective tool for atomic spectroscopy and site-specific photochemistry. Its most novel capability is application to molecular fragmentation after K-shell vacancy production in atoms distinguished only by their chemical environment.
|
|
| 7. |
- Fasshauer, Elke, et al.
(författare)
-
Theoretical and experimental investigation of Electron Transfer Mediated Decay in ArKr clusters
- 2017
-
Ingår i: Chemical Physics. - : Elsevier BV. - 0301-0104 .- 1873-4421. ; 482, s. 226-238
-
Tidskriftsartikel (refereegranskat)abstract
- We investigate the electronic decay of an Ar 3s(-1) vacancy in medium sized ArKr clusters. The only energetically accessible, radiationless decay mechanism is Electron Transfer Mediated Decay Three (ETMD3). Here, the argon vacancy is filled by an electron from one krypton atom, and the excess energy is transferred to a second krypton atom which consequently emits an electron. For the theoretical calculation of ETMD3 spectra, in a bottom-up approach, we study the dependence of the decay width on the geometry of elementary sets of three atoms, from which any cluster can be composed. We simulate the ETMD3 spectra of medium sized ArKr clusters and compare the resulting spectra to experimental ETMD electron spectra presented earlier (Forstel et al, 2011) and in this work. We show that ETMD3 is the dominating relaxation mechanism for the cases studied here. Experimental secondary electron spectra from ArKr clusters are compared to pure Ar and pure Kr clusters.
|
|
| 8. |
- Feifel, Raimund, et al.
(författare)
-
Ultrafast molecular three-electron Auger process
- 2016
-
Ingår i: Physical Review Letters. - 0031-9007 .- 1079-7114. ; 116
-
Tidskriftsartikel (refereegranskat)abstract
- Three-electron Auger decay is an exotic and elusive process, in which two outer-shell electrons simultaneously refill an inner-shell double vacancy with emission of a single Auger electron. Such transitions are forbidden by the many-electron selection rules, normally making their decay lifetimes orders of magnitude longer than the few-femtosecond lifetimes of normal (two-electron) Auger decay. Here we present theoretical predictions and direct experimental evidence for a few-femtosecond three-electron Auger decay of a double inner-valence-hole state in CH3F. Our analysis shows that in contrast to double core holes, double inner-valence vacancies in molecules can decay exclusively by this ultrafast three-electron Auger process, and we predict that this phenomenon occurs widely.
|
|
| 9. |
- Foerstel, Marko, et al.
(författare)
-
Long-Range Interatomic Coulombic Decay in ArXe Clusters : Experiment and Theory
- 2016
-
Ingår i: The Journal of Physical Chemistry C. - : American Chemical Society (ACS). - 1932-7447 .- 1932-7455. ; 120:40, s. 22957-22971
-
Tidskriftsartikel (refereegranskat)abstract
- We report autoionization channels of Ar inner valence ionized states in mixed AtXe dusters and compare our experimental data obtained by electron electron-electron coincidence spectroscopy to our theoretical simulations for representative cluster structures. The combined experimental and theoretical data show that the autoionization of Ar 3s(-1) in ArXe is dominated by interatomic coulombic decay(ICD) to Xe atoms in the second and higher coordination shells of the originally excited atom. Clusters with a range of sites, compositions, and structures were probed. The Xe content in the clusters was varied between 10% and 53%. Besides ICD, also electron transfer mediated, decay (ETMD(3)) was found important in many of the calculated spectra, although it is seen with less intensity in the experimental spectra. From the calculations, we identify structural motifs in which the ETMD rate is minimized vs the ICD rate and suggest that these are preferentially realized in our experiment in which clusters are formed by supersonic expansion of an Ar-Xe mixture. Suggested cluster structures either feature a dear segregation between Ar and Xe fractions, e.g., Xe core-Ar shell systems, or contain a few Xe atoms singled out at surface sites on an Ar cluster. These structures differ significantly from the majority of calculated minimum energy structures for ArXe systems of 38 atoms, which might show that the latter, annealed structures are not realized in our experiment. We show experimentally that the relaxation of Ar inner valence states by ICD and ETMD together has an efficiency of unity, within the experimental accuracy, for all dusters probed, except those with the lowest Xe content. The outer valence photoelectron spectra of ArXe are discussed also.
|
|
| 10. |
- Foerstel, Marko, et al.
(författare)
-
Observation of electronic energy bands in argon clusters
- 2010
-
Ingår i: Physical Review B. Condensed Matter and Materials Physics. - 1098-0121 .- 1550-235X. ; 82:12, s. 125450-
-
Tidskriftsartikel (refereegranskat)abstract
- The 3p valence region of argon clusters has been investigated with photoemission near the photoionization threshold. A strong feature between 14.6 and 15.3 eV binding energy shows a photon-energy dependence indicative of electronic-energy band dispersion. A similar feature at approximately the same binding energy and with a similar dispersion occurs in photoemission spectra of both the ordered and disordered solids. The effect is already fully developed for scaling-law mean cluster sizes < N > of approximately 200 atoms, thus showing an early onset of bulklike electronic properties.
|
|
