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Linusson, Per
Publikasjoner (10 av 38) Visa alla publikasjoner
Zagorodskikh, S., Vapa, M., Vahtras, O., Zhaunerchyk, V., Mucke, M., Eland, J. H., . . . Feifel, R. (2016). An experimental and theoretical study of core-valence double ionisation of acetaldehyde (ethanal). Physical Chemistry, Chemical Physics - PCCP, 18(4), 2535-2547
Åpne denne publikasjonen i ny fane eller vindu >>An experimental and theoretical study of core-valence double ionisation of acetaldehyde (ethanal)
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2016 (engelsk)Inngår i: Physical Chemistry, Chemical Physics - PCCP, ISSN 1463-9076, E-ISSN 1463-9084, Vol. 18, nr 4, s. 2535-2547Artikkel i tidsskrift (Fagfellevurdert) Published
Abstract [en]

Core-valence double ionisation spectra of acetaldehyde (ethanal) are presented at photon energies above the carbon and oxygen 1s ionisation edges, measured by a versatile multi-electron coincidence spectroscopy technique. We use this molecule as a testbed for analyzing core-valence spectra by means of quantum chemical calculations of transition energies. These theoretical approaches range from two simple models, one based on orbital energies corrected by core valence interaction and one based on the equivalent core approximation, to a systematic series of quantum chemical electronic structure methods of increasing sophistication. The two simple models are found to provide a fast orbital interpretation of the spectra, in particular in the low energy parts, while the coverage of the full spectrum is best fulfilled by correlated models. CASPT2 is the most sophisticated model applied, but considering precision as well as computational costs, the single and double excitation configuration interaction model seems to provide the best option to analyze core-valence double hole spectra.

HSV kategori
Identifikatorer
urn:nbn:se:su:diva-127877 (URN)10.1039/c5cp05758b (DOI)000369506000030 ()26700657 (PubMedID)2-s2.0-84955271543 (Scopus ID)
Tilgjengelig fra: 2016-06-21 Laget: 2016-03-14 Sist oppdatert: 2022-10-17bibliografisk kontrollert
Zagorodskikh, S., Eland, J. H. D., Zhaunerchyk, V., Mucke, M., Squibb, R. J., Linusson, P. & Feifel, R. (2016). Mechanisms of site-specific photochemistry following core-shell ionization of chemically inequivalent carbon atoms in acetaldehyde (ethanal). Journal of Chemical Physics, 145(12), Article ID 124302.
Åpne denne publikasjonen i ny fane eller vindu >>Mechanisms of site-specific photochemistry following core-shell ionization of chemically inequivalent carbon atoms in acetaldehyde (ethanal)
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2016 (engelsk)Inngår i: Journal of Chemical Physics, ISSN 0021-9606, E-ISSN 1089-7690, Vol. 145, nr 12, artikkel-id 124302Artikkel i tidsskrift (Fagfellevurdert) Published
Abstract [en]

Site-specific fragmentation upon 1s photoionisation of acetaldehyde has been studied using synchrotron radiation and a multi-electron-ion coincidence technique based on a magnetic bottle. Experimental evidence is presented that bond rupture occurs with highest probability in the vicinity of the initial charge localisation and possible mechanisms are discussed. We find that a significant contribution to site-specific photochemistry is made by different fragmentation patterns of individual quantum states populated at identical ionisation energies.

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Identifikatorer
urn:nbn:se:su:diva-136110 (URN)10.1063/1.4962823 (DOI)000385562600024 ()2-s2.0-84988851336 (Scopus ID)
Tilgjengelig fra: 2016-11-29 Laget: 2016-11-29 Sist oppdatert: 2022-10-17bibliografisk kontrollert
Feifel, R., Eland, J. H. D., Squibb, R. J., Mucke, M., Zagorodskikh, S., Linusson, P., . . . Averbukh, V. (2016). Ultrafast Molecular Three-Electron Auger Decay. Physical Review Letters, 116(7), Article ID 073001.
Åpne denne publikasjonen i ny fane eller vindu >>Ultrafast Molecular Three-Electron Auger Decay
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2016 (engelsk)Inngår i: Physical Review Letters, ISSN 0031-9007, E-ISSN 1079-7114, Vol. 116, nr 7, artikkel-id 073001Artikkel i tidsskrift (Fagfellevurdert) Published
Abstract [en]

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 threeelectron Auger process, and we predict that this phenomenon occurs widely.

HSV kategori
Identifikatorer
urn:nbn:se:su:diva-128174 (URN)10.1103/PhysRevLett.116.073001 (DOI)000370622000004 ()2-s2.0-84959421898 (Scopus ID)
Tilgjengelig fra: 2016-03-29 Laget: 2016-03-21 Sist oppdatert: 2022-10-19bibliografisk kontrollert
Mucke, M., Zhaunerchyk, V., Frasinski, L. J., Squibb, R. J., Siano, M., Eland, J. H., . . . Feifel, R. (2015). Covariance mapping of two-photon double core hole states in C2H2 and C2H6 produced by an x-ray free electron laser. New Journal of Physics, 17, Article ID 073002.
Åpne denne publikasjonen i ny fane eller vindu >>Covariance mapping of two-photon double core hole states in C2H2 and C2H6 produced by an x-ray free electron laser
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2015 (engelsk)Inngår i: New Journal of Physics, E-ISSN 1367-2630, Vol. 17, artikkel-id 073002Artikkel i tidsskrift (Fagfellevurdert) Published
Abstract [en]

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.

Emneord
double core hole, free electron laser, few-photon process, covariance mapping
HSV kategori
Identifikatorer
urn:nbn:se:su:diva-119303 (URN)10.1088/1367-2630/17/7/073002 (DOI)000357262900002 ()
Tilgjengelig fra: 2015-08-04 Laget: 2015-08-03 Sist oppdatert: 2024-01-17bibliografisk kontrollert
Eland, J. H., Squibb, R. J., Mucke, M., Zagorodskikh, S., Linusson, P. & Feifel, R. (2015). Direct observation of three-electron collective decay in a resonant Auger process. New Journal of Physics, 17, Article ID 122001.
Åpne denne publikasjonen i ny fane eller vindu >>Direct observation of three-electron collective decay in a resonant Auger process
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2015 (engelsk)Inngår i: New Journal of Physics, E-ISSN 1367-2630, Vol. 17, artikkel-id 122001Artikkel i tidsskrift (Fagfellevurdert) Published
Abstract [en]

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.

Emneord
collective Auger decay, multi-electron coincidence, inner shell vacancies
HSV kategori
Identifikatorer
urn:nbn:se:su:diva-125782 (URN)10.1088/1367-2630/17/12/122001 (DOI)000367016200001 ()
Tilgjengelig fra: 2016-01-27 Laget: 2016-01-18 Sist oppdatert: 2024-01-17bibliografisk kontrollert
Zhaunerchyk, V., Kamińska, M., Mucke, M., Squibb, R. J., Eland, J. H., Piancastelli, M. N., . . . Feifel, R. (2015). Disentangling formation of multiple-core holes in aminophenol molecules exposed to bright X-FEL radiation. Journal of Physics B: Atomic, Molecular and Optical Physics, 48(24), Article ID 244003.
Åpne denne publikasjonen i ny fane eller vindu >>Disentangling formation of multiple-core holes in aminophenol molecules exposed to bright X-FEL radiation
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2015 (engelsk)Inngår i: Journal of Physics B: Atomic, Molecular and Optical Physics, ISSN 0953-4075, E-ISSN 1361-6455, Vol. 48, nr 24, artikkel-id 244003Artikkel i tidsskrift (Fagfellevurdert) Published
Abstract [en]

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).

Emneord
multiple ionization processes, double core hole, covariance mapping
HSV kategori
Identifikatorer
urn:nbn:se:su:diva-126785 (URN)10.1088/0953-4075/48/24/244003 (DOI)000368622900004 ()
Tilgjengelig fra: 2016-06-28 Laget: 2016-02-15 Sist oppdatert: 2022-03-23bibliografisk kontrollert
Zagorodskikh, S., Zhaunerchyk, V., Mucke, M., Eland, J. H., Squibb, R. J., Karlsson, L., . . . Feifel, R. (2015). Single-photon double and triple ionization of acetaldehyde (ethanal) studied by multi-electron coincidence spectroscopy. Chemical Physics, 463, 159-168
Åpne denne publikasjonen i ny fane eller vindu >>Single-photon double and triple ionization of acetaldehyde (ethanal) studied by multi-electron coincidence spectroscopy
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2015 (engelsk)Inngår i: Chemical Physics, ISSN 0301-0104, E-ISSN 1873-4421, Vol. 463, s. 159-168Artikkel i tidsskrift (Fagfellevurdert) Published
Abstract [en]

Single-photon multiple ionization processes of acetaldehyde (ethanal) have been experimentally investigated by utilizing a multi-particle coincidence technique based on the time-of-flight magnetic bottle principle, in combination with either a synchrotron radiation source or a pulsed helium discharge lamp. The processes investigated include double and triple ionization in the valence region as well as single and double Auger decay of core-ionized acetaldehyde. The latter are studied site-selectively for chemically different carbon core vacancies, scrutinizing early theoretical predictions specifically made for the case of acetaldehyde. Moreover, Auger processes in shake-up and core-valence ionized states are investigated. In the cases where the processes involve simultaneous emission of two electrons, the distributions of the energy sharing are presented, emphasizing either the knock-out or shake-off mechanism.

Emneord
Acetaldehyde, Double ionization, Triple ionisation, Site-specific Auger decay
HSV kategori
Identifikatorer
urn:nbn:se:su:diva-125647 (URN)10.1016/j.chemphys.2015.10.006 (DOI)000365582100021 ()2-s2.0-84947805695 (Scopus ID)
Tilgjengelig fra: 2016-01-19 Laget: 2016-01-15 Sist oppdatert: 2022-10-17bibliografisk kontrollert
Andersson, J., Beerwerth, R., Linusson, P., Eland, J. H., Zhaunerchyk, V., Fritzsche, S. & Feifel, R. (2015). Triple ionization of atomic Cd involving 4p(-1) and 4s(-1) inner-shell holes. Physical Review A. Atomic, Molecular, and Optical Physics, 92(2), Article ID 023414.
Åpne denne publikasjonen i ny fane eller vindu >>Triple ionization of atomic Cd involving 4p(-1) and 4s(-1) inner-shell holes
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2015 (engelsk)Inngår i: Physical Review A. Atomic, Molecular, and Optical Physics, ISSN 1050-2947, E-ISSN 1094-1622, Vol. 92, nr 2, artikkel-id 023414Artikkel i tidsskrift (Fagfellevurdert) Published
Abstract [en]

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.

HSV kategori
Identifikatorer
urn:nbn:se:su:diva-120182 (URN)10.1103/PhysRevA.92.023414 (DOI)000359438400010 ()2-s2.0-84939431253 (Scopus ID)
Tilgjengelig fra: 2015-09-07 Laget: 2015-09-02 Sist oppdatert: 2022-10-17bibliografisk kontrollert
Hedin, L., Tashiro, M., Linusson, P., Eland, J. H., Ehara, M., Ueda, K., . . . Feifel, R. (2014). N1s and O1s double ionization of the NO and N2O molecules. Journal of Chemical Physics, 140(4), 044309
Åpne denne publikasjonen i ny fane eller vindu >>N1s and O1s double ionization of the NO and N2O molecules
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2014 (engelsk)Inngår i: Journal of Chemical Physics, ISSN 0021-9606, E-ISSN 1089-7690, Vol. 140, nr 4, s. 044309-Artikkel i tidsskrift (Fagfellevurdert) Published
Abstract [en]

Single-site N1s and O1s double core ionisation of the NO and N2O molecules has been studied using a magnetic bottle many-electron coincidence time-of-flight spectrometer at photon energies of 1100 eV and 1300 eV. The double core hole energies obtained for NO are 904.8 eV (N1s(-2)) and 1179.4 eV (O1s(-2)). The corresponding energies obtained for N2O are 896.9 eV (terminal N1s(-2)), 906.5 eV (central N1s(-2)), and 1174.1 eV (O1s(-2)). The ratio between the double and single ionisation energies are in all cases close or equal to 2.20. Large chemical shifts are observed in some cases which suggest that reorganisation of the electrons upon the double ionization is significant. Delta-self-consistent field and complete active space self-consistent field (CASSCF) calculations were performed for both molecules and they are in good agreement with these results. Auger spectra of N2O, associated with the decay of the terminal and central N1s(-2) as well as with the O1s(-2) dicationic states, were extracted showing the two electrons emitted as a result of filling the double core holes. The spectra, which are interpreted using CASSCF and complete active space configuration interaction calculations, show atomic-like character. The cross section ratio between double and single core hole creation was estimated as 1.6 x 10(-3) for nitrogen at 1100 eV and as 1.3 x 10(-3) for oxygen at 1300 eV.

sted, utgiver, år, opplag, sider
American Institute of Physics (AIP), 2014
HSV kategori
Identifikatorer
urn:nbn:se:su:diva-101747 (URN)10.1063/1.4853655 (DOI)000331211700035 ()2-s2.0-84902187845 (Scopus ID)
Forskningsfinansiär
Swedish Research CouncilKnut and Alice Wallenberg Foundation
Merknad

AuthorCount:10;

Other funders;

Goran Gustafsson Foundation (UU/KTH) 

Japan Society for the Promotion of Science (JSPS)  Ministry of Education, Culture, Sports, Science and Technology of Japan;

European Community - Research Infrastructure Action under the FP6 "Structuring the European Research Area" Programme (through the Integrated Infrastructure Initiative "Integrating Activity on Synchrotron and Free Electron Laser Science") R II 3-CT-2004-506008 

Tilgjengelig fra: 2014-03-18 Laget: 2014-03-14 Sist oppdatert: 2022-10-13bibliografisk kontrollert
Hedin, L., Tashiro, M., Linusson, P., Eland, J. H., Ehara, M., Ueda, K., . . . Feifel, R. (2014). Single site double core level ionisation of OCS. Chemical Physics, 439, 111-116
Åpne denne publikasjonen i ny fane eller vindu >>Single site double core level ionisation of OCS
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2014 (engelsk)Inngår i: Chemical Physics, ISSN 0301-0104, E-ISSN 1873-4421, Vol. 439, s. 111-116Artikkel i tidsskrift (Fagfellevurdert) Published
Abstract [en]

Single site O1s, C1s and S2p double ionisation of the OCS molecule has been investigated using a magnetic bottle multi-electron coincidence time-of-flight spectrometer. Photon energies of 1300, 750 and 520 eV, respectively, were used for the ionisation, and spectra were obtained from which the double core ionisation energies could be determined. The energies measured for 1s double ionisation are 1172 eV (O1s(-2)) and 659 eV (C1s(-2)). For the S2p double ionisation three dicationic states are expected, P-3, D-1 and S-1. The ionisation energies obtained for these states are 373 eV (P-3), 380 eV (D-1) and 388 eV (S-1). The ratio between the double and single core ionisation energies are in all cases equal or close to 2.20. Auger spectra of OCS, associated with the O1s(-2), C1s(-2) and S2p(-2) dicationic states, were also recorded incorporating both electrons emitted as a result of the filling of the two core vacancies. As for other small molecules, the spectra show an atomic-like character with Auger bands located in the range 480-560 eV for oxygen, 235-295 eV for carbon and 100-160 eV for sulphur. The interpretation of the spectra is supported by CASSCF and CASCI calculations. The cross section ratio between double and single core hole creation was estimated as 3.7 x 10(-4) for oxygen at 1300 eV, 3.7 x 10(-4) for carbon at 750 eV and as 2.2 x 10(-3) for sulphur at 520 eV.

Emneord
Double core hole states, Electron spectra, Magnetic bottle multi-electron coincidence spectrometer, Cross section ratios
HSV kategori
Identifikatorer
urn:nbn:se:su:diva-106564 (URN)10.1016/j.chemphys.2014.05.012 (DOI)000338705600015 ()2-s2.0-84903198750 (Scopus ID)
Merknad

AuthorCount:9;

Tilgjengelig fra: 2014-08-15 Laget: 2014-08-12 Sist oppdatert: 2022-10-13bibliografisk kontrollert
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