2018 |
Blancard C., Cubaynes D., Guilbaud S., & and Bizau J.-M. (2018). Absolute Photoionization Cross Section for Fe6+ to Fe10+ Ions in the Photon Energy Region of the 2p–3d Resonance Lines. The Astrophysical Journal, 853(1), 32.
Résumé: Resonant single photoionization cross sections of Fen+ (n = 6 to 10) ions have been measured in absolute values using a merged-beams setup at the SOLEIL synchrotron radiation facility. Photon energies were between about 710 and 780 eV, covering the range of the 2p–3d transitions. The experimental cross sections are compared to calculations we performed using a multi-configuration Dirac–Fock code and the OPAS code dedicated to radiative opacity calculations. Comparisons are also done with the Chandra X-ray observatory NGC 3783 spectra and with the results of previously published calculations.
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Puglisi A., M. T., Kennedy E.T., Mosnier J.P., Bizau J.M., Cubaynes D., Sisourat N. and Carniato S. (2018). X-ray photochemistry of carbon hydride molecular ions. Physical Chemistry Chemical Physics, 20, 4415.
Résumé: Hydride molecular ions are key ingredients of the interstellar chemistry since they are precursors of more complex molecules. In regions located near a soft X-ray source these ions may resonantly absorb an X-ray photon which triggers a complex chain of reactions. In this work, we simulate ab initio the X-ray absorption spectrum, Auger decay processes and the subsequent fragmentation dynamics of two hydride molecular ions, namely CH2+ and CH3+. We show that these ions feature strong X-ray absorption resonances which relax through Auger decay within 7 fs. The doubly-charged ions thus formed mostly dissociate into smaller ionic carbon fragments: in the case of CH2+, the dominant products are either C+/H+/H or CH+/H+. For CH3+, the system breaks primary into CH2+ and H+, which provides a new route to form CH2+ near a X-ray source. Furthermore, our simulations provide the branching ratios of the final products formed after the X-ray absorption as well as their kinetic and internal energy distributions. Such data can be used in the chemistry models of the interstellar medium.
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2017 |
Blancard C., Cubaynes D., Guilbaud S., & and Bizau J.-M. (2017). L -shell photoionization of Mn 5+ to Mn 8+ ions. PHYSICAL REVIEW A, 96, 013410.
Résumé: Resonant photoionization cross sections of Mnn+ (n=5 to 8) ions are measured in absolute values in the photon energy range of the 2p→3d transitions (645-690eV)using a merged-beams setup at the SOLEIL synchrotron radiation facility. The experimental cross sections are compared to calculations we performed using a multiconfiguration Dirac-Fock code and the opas code dedicated to radiative opacity calculations of hot and dense plasmas. Both calculations reproduce the measurements well.
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Douix S., Duflot D., Cubaynes D., Bizau J.M., & and Giuliani A. (2017). Photoionization of the Buckminsterfullerene Cation. J. Phys. Chem. Lett, 8(1), 7–12.
Résumé: Photoionization of a buckminsterfullerene ion is investigated using an ion trap and a merged beam setup coupled to synchrotron radiation beamlines and compared to theoretical calculations. Absolute measurements derived from the ion trap experiment allow discrepancies concerning the photoionization cross section of C60+ to be solved.
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Khalal M. A., L. P., Andric L., Palaudoux J., Penent F., Bučar K., Žitnik M., Püttner R., Jänkälä K., Cubaynes D., Guilbaud S., and Bizau J.-M. (2017). 4d -inner-shell ionization of Xe+ ions and subsequent Auger decay. PHYSICAL REVIEW A, 96, 013412.
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Khalal M.A., S. J., Jänkälä K., Huttula S-M, Huttula M, Bizau J-M, Cubaynes D., Guilbaud S., Ito K., Andric L., Feng J., Lablanquie P., Palaudoux J. and Penent F. (2017). Multielectron spectroscopy: energy levels of K n+ and Rb n+ ions (n = 2, 3, 4). Journal of Physics B: Atomic, Molecular and Optical Physics, 50(22), 225003.
Résumé: A magnetic bottle time-of-flight spectrometer has been used to perform spectroscopy of K n+ and Rb n+ states with ionization degrees n of 2, 3 and 4. Energy levels are directly measured by detecting in coincidence the n electrons that are emitted as a result of single photon absorption. Experimental results are compared with the energies from the NIST atomic database and ab initio multiconfiguration Dirac–Fock calculations. Previously unidentified 3p 4(3P)3d 1 4D energy levels of K2+ are assigned.
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Lablanquie P., K. M. A., Andric L., Palaudoux J., Penent F., Bizau J-M, Cubaynes D., Jänkälä K., Hikosaka Y., Ito K., Bučar K., Žitnikg M. (2017). Multi-electron coincidence spectroscopy: Triple Auger decay of Ar 2p and 2s holes. Journal of Electron Spectroscopy and Related Phenomena, 220, 125–132.
Résumé: The detailed study of single photon multiple ionization processes requires the detection in coincidence of all the electrons emitted from the same ionization event. The advent of magnetic bottle experiments made possible the development of this multi-electron coincidence spectroscopy. First we will briefly review the achievements of this technique. Then we will illustrate more specifically its high sensitivity taking as an example the decay by emission of three Auger electrons of 2p and 2s holes in argon. Our results show that the processes are completely different depending on the initial core hole: the three Auger electrons are emitted dominantly in a simultaneous path for the 2p case, but in cascade for the 2s one.
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2016 |
Bizau, J. M., Cubaynes, D., Guilbaud, S., El Hassan, N., Al Shorman, M. M., Bouisset, E., Guigand, J., Moustier, O., Marie, A., Nadal, E., Robert, E., Nicolas, C., & Miron, C. (2016). A merged-beam setup at SOLEIL dedicated to photoelectron-photoion coincidence studies on ionic species. Journal Of Electron Spectroscopy And Related Phenomena, 210, 5–12.
Résumé: We describe the merged-beam setup permanently installed on a dedicated optical branch of the PLEIADES beamline at SOLEIL, the French synchrotron radiation facility in St-Aubin, delivering photons in the 10-1000 eV photon energy range. The setup is designed both for photoion and photoelectron spectroscopy experiments on atomic and molecular ions. Ion spectrometry is dedicated to the deterrnination of absolute single and multiple photoionization cross sections. Electron spectroscopy brings additional information on the non-radiative decay of inner-vacancies produced in the photoionization processes and allows for the determination of partial cross sections. Efficient reduction of the background in the electron spectra is achieved by the use of the electron-ion coincidence technique. Examples of photoion and photoelectron spectra are given for the Xe5+ ion. (C) 2016 Elsevier B.V. All rights reserved.
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Bizau, J. M., Cubaynes, D., Guilbaud, S., Penent, F., Lablanquie, P., Andric, L., Palaudoux, J., Al Shorman, M. M., & Blancard, C. (2016). Photoelectron Spectroscopy of Ions: Study of the Auger Decay of the 4d -> nf (n=4,5) Resonances in Xe5+ Ion. Physical Review Letters, 116(10), 103001.
Résumé: We have studied, for the first time by electron spectroscopy, the Auger decay of the 4d -> nf ( n = 4,5) resonances in Xe5+ ion. By detecting in coincidence the Auger electrons with the resulting Xe6+ ions, we unravel the contribution of the different final ionic states to the total cross section measured by ion spectroscopy. A strong intensity of 5s5p satellite lines has been observed, up to 4 times stronger than the 5s(2) main lines. This unexpected behavior is confirmed by multiconfiguration Dirac- Fock calculations. This technique provides the most stringent test for theoretical models and allows us to disentangle the contribution of ions in the ground and metastable states in the target beam.
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McLaughlinB. M., Bizau J.-M., Cubaynes D., Guilbaud S., Douix S, Al Shorman M. M., El Ghazaly M. O. A., Sakho I., & Gharaibeh M. F. (2016). K-shell photoionization of O4 + and O5 + ions: experiment and theory. Royal Astronomical Society, 465, 4690.
Résumé: Absolute cross-sections for the K-shell photoionization of Be-like (O4 +) and Li-like (O5 +) atomic oxygen ions were measured for the first time (in their respective K-shell regions) by employing the ion–photon merged-beam technique at the SOLEIL synchrotron-radiation facility in Saint-Aubin, France. High-resolution spectroscopy with E/ΔE ≈ 3200 (≈170 meV, full width at half-maximum) was achieved with photon energy from 550 to 670 eV. Rich resonance structure observed in the experimental spectra is analysed using the R-matrix with pseudo-states (RMPS) method. Results are also compared with the screening constant by unit nuclear charge (SCUNC) calculations. We characterize and identify the strong 1s → 2p resonances for both ions and the weaker 1s → np resonances (n ≥ 3) observed in the K-shell spectra of O4 +.
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Mosnier, J. P., Kennedy, E. T., van Kampen, P., Cubaynes, D., Guilbaud, S., Sisourat, N., Puglisi, A., Carniato, S., & Bizau, J. M. (2016). Inner-shell photoexcitations as probes of the molecular ions CH+, OH+, and SiH+: Measurements and theory. Physical Review A, 93, 061401.
Résumé: Spectral probes for the CH+, OH+, and SiH+ hydride molecular ions that play key roles in astrophysics and plasma processes are presented. The merged-beam technique at the SOLEIL synchrotron was used to record the photoionization (ion yield) spectra of CH+, OH+, and SiH+ and that of their parent atomic ions, in the K-shell and L-shell regions, respectively. Energies and oscillator strengths for the K alpha (CH+ and OH+) and La (SiH+) transitions were determined from the spectra. Ab initio calculations interpret the experimental data in terms of contributions from ground and excited valence electronic states.
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2015 |
Bizau, J. M., Cubaynes, D., Guilbaud, S., Al Shorman, M. M., Gharaibeh, M. F., Ababneh, I. Q., Blancard, C., & McLaughlin, B. M. (2015). K-shell photoionization of O+ and O2+ ions: Experiment and theory. Physical Review A, 92, 023401.
Résumé: Absolute cross sections for the single and double K-shell photoionization of carbonlike O2+ and nitrogenlike O+ ions were measured in the 526-620-eV photon energy range by employing the ion-photon merged-beam technique at the SOLEIL synchrotron radiation facility. High-resolution spectroscopy up to E/Lambda E approximate to 5300 was achieved. Rich resonance structures observed in the experimental spectra are analyzed and identified with the aid of R-matrix and multiconfiguration Dirac-Fock (MCDF) methods. For these two atomic oxygen ions of particular astrophysical interest we characterized the strong 1s -> 2p and the weaker 1s -> np (n > 2) resonances observed. A detailed comparison of the energies of the 1s -> 2p resonances in the first members of the oxygen isonuclear sequence measured by synchrotron based experiments and the Chandra and XMM-Newton x-ray satellites is presented.
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Bizau, J. M., Cubaynes, D., Guilbaud, S., Al Shorman, M. M., Penent, F., Lablanquie, P., Andric, L., Palaudoux, J., & Blancard, C. (2015). Auger decay of the 4d(9)5s(2)5pnf excited states of Xe5+ ion. In Xxix International Conference On Photonic (Vol. 635).
Résumé: The Auger decay of the 4d --> nf (n = 4 to 6) photoexcitations in Xe5+ ion has been measured using electron spectrometry. MCDF calculations allow to interpret the recorded electron spectra.
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Gharaibeh, M. F., Bizau, J. M., Cubaynes, D., Guilbaud, S., Al Shorman, M. M., Ababneh, I. Q., Sakho, I., Blancard, C., & McLaughlin, B. M. (2015). K-Shell Photoionization of the Oxygen Isonuclear Sequence. In Xxix International Conference On Photonic (Vol. 635).
Résumé: K-shell photoionization cross-section measurements for the oxygen isonuclear sequence from N-like to Li-like made at the SOLEIL Light Source are compared with SUNC, MCDF and R-matrix calculations.
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Palaudoux, J., Sheinerman, S., Soronen, J., Huttula, S. M., Huttula, M., Jankala, K., Andric, L., Ito, K., Lablanquie, P., Penent, F., Bizau, J. M., Guilbaud, S., & Cubaynes, D. (2015). Valence Auger decay following 3s photoionization in potassium. Physical Review A, 92(1), 012510.
Résumé: We have studied photoionization in the inner valence 3s subshell of K and the spectroscopic properties of the two 3s(-1) (S-1) and (S-3) resulting states. Similar to the Rb and Cs cases, the lifetime widths of the (S-1) and (S-3) states are found to be markedly different, due to the electron correlation effects. The main part of the study deals with the subsequent Auger decay of the 3s(-1) states, which have the particularity to involve low energy (similar to 5 eV) Auger electrons. A magnetic bottle spectrometer with a multicoincidence technique has been used to observe and filter the Auger spectra with respect to the K2+ final state. The evolution of these Auger spectra has been investigated near the ionization threshold. They show strong post-collision interaction (PCI) effects, which are well reproduced by semiclassical and eikonal models. They reveal the importance of the photoelectron-Auger-electron interaction associated with these low energy Auger electrons.
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Sheinerman, S., Lablanquie, P., Andric, L., Ito, K., Palaudoux, J., Huttula, S. M., Huttula, M., Jankala, K., Soronen, J., Bizau, J., Guilbaud, S., Cubaynes, D., & Penent, F. (2015). Post-collision interaction in Potassium 3s photoionization. In Xxix International Conference On Photonic (Vol. 635).
Résumé: The post-collision interaction (PCI) distortion of the Auger electron line shapes after K 3s photoionization is revealed in coincidence measurements and confirmed by calculations.
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2014 |
Gharaibeh, M. F., El Hassan, N., Al Shorman, M. M., Bizau, J. M., Cubaynes, D., Guilbaud, S., Sakho, I., Blancard, C., & McLaughlin, B. M. (2014). K-shell photoionization of B-like atomic nitrogen ions: experiment and theory. JOURNAL OF PHYSICS B-ATOMIC MOLECULAR AND OPTICAL PHYSICS, 47(6), 065201.
Résumé: Measurements of absolute cross sections for the K-shell photoionization of B-like atomic nitrogen ions were carried out utilizing the ion-photon merged-beam technique at the SOLEIL synchrotron radiation facility in Saint-Aubin, France. High-resolution spectroscopy with E/Delta E approximate to 13,500 was the maximum resolution achieved. We have investigated two photon energy regions: 404-409 eV and 439-442 eV. Resonance peaks found in the experimental measured cross sections are compared with theoretical estimates from the multi-configuration Dirac-Fock, R-matrix and empirical methods, allowing identification of the strong 1s -> 2p and the weaker 1s -> 3p resonances in the observed K-shell spectra of this B-like nitrogen ion.
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Helml, W., Maier, A. R., Schweinberger, W., Grguras, I., Radcliffe, P., Doumy, G., Roedig, C., Gagnon, J., Messerschmidt, M., Schorb, S., Bostedt, C., Gruener, F., DiMauro, L. F., Cubaynes, D., Bozek, J. D., Tschentscher, T., Costello, J. T., Meyer, M., Coffee, R., Duesterer, S., Cavalieri, A. L., & Kienberger, R. (2014). Measuring the temporal structure of few-femtosecond free-electron laser X-ray pulses directly in the time domain. NATURE PHOTONICS, 8(12), 950–957.
Résumé: Short-wavelength free-electron lasers are now well established as essential and unrivalled sources of ultrabright coherent X-ray radiation. One of the key characteristics of these intense X-ray pulses is their expected few-femtosecond duration. No measurement has succeeded so far in directly determining the temporal structure or even the duration of these ultrashort pulses in the few-femtosecond range. Here, by deploying the so-called streaking spectroscopy technique at the Linac Coherent Light Source, we demonstrate a non-invasive scheme for temporal characterization of X-ray pulses with sub-femtosecond resolution. This method is independent of photon energy, decoupled from machine parameters, and provides an upper bound on the X-ray pulse duration. We measured the duration of the shortest X-ray pulses currently available to be on average no longer than 4.4 fs. Analysing the pulse substructure indicates a small percentage of the free-electron laser pulses consisting of individual high-intensity spikes to be on the order of hundreds of attoseconds.
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Kennedy, E. T., Mosnier, J. - P., Van Kampen, P., Cubaynes, D., Guilbaud, S., Blancard, C., McLaughlin, B. M., & Bizau, J. - M. (2014). Photoionization cross sections of the aluminumlike Si+ ion in the region of the 2p threshold (94-137 eV). PHYSICAL REVIEW A, 90, 063409.
Résumé: We present measurements of the absolute photoionization cross section of the aluminumlike Si+ ion over the 94-137 eV photon energy range. The measurements were performed using the merged-beam setup on the PLEIADES beamline at the SOLEIL synchrotron radiation facility. Signals produced in the Si2+ and Si3+ photoionization channels of the 2p subshell of the Si+ ion from both the 1s(2)2s(2)2p(6)3s(2)3p P-2(1/2,3/2) ground levels and the 1s(2)2s(2)2p(6)3s(3)p(2 4)P metastable levels were observed. Absolute cross sections were determined. Calculations of the 2p inner-shell photoionization cross sections were carried out using the multiconfiguration Dirac-Fock and Dirac-Coulomb R-matrix theoretical approaches and are compared with experiment.
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McLaughlin, B. M., Bizau, J. M., Cubaynes, D., Al Shorman, M. M., Guilbaud, S., Sakho, I., Blancard, C., & Gharaibeh, M. F. (2014). K-shell photoionization of B-like oxygen (O3+) ions: experiment and theory. JOURNAL OF PHYSICS B-ATOMIC MOLECULAR AND OPTICAL PHYSICS, 47(11), 115201.
Résumé: Absolute cross sections for the K-shell photoionization of boron-like (B-like) O3+ ions were measured by employing the ion-photon merged-beam technique at the SOLEIL synchrotron-radiation facility in Saint-Aubin, France. High-resolution spectroscopy with E/Delta E approximate to 5000 (approximate to 110 meV, full width half maximum) was achieved with photon energy from 540 up to 600 eV. Several theoretical approaches, including R-matrix, multi-configuration Dirac-Fock and screening constant by unit nuclear charge were used to identify and characterize the strong 1s -> 2p and the weaker 1s -> 3p resonances observed in the K-shell spectra of this ion. The trend of the integrated oscillator strength and autoionization width (natural line width) of the strong 1s -> 2p resonances along the first few ions of the B-like sequence is discussed.
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2013 |
Al Shorman, M. M., Gharaibeh, M. F., Bizau, J. M., Cubaynes, D., Guilbaud, S., El Hassan, N., Miron, C., Nicolas, C., Robert, E., Sakho, I., Blancard, C., & McLaughlin, B. M. (2013). K-shell photoionization of Be-like and Li-like ions of atomic nitrogen: experiment and theory. JOURNAL OF PHYSICS B-ATOMIC MOLECULAR AND OPTICAL PHYSICS, 46(19), 195701.
Résumé: Absolute cross sections for the K-shell photoionization of Be-like and Li-like atomic nitrogen ions were measured by employing the ion-photon merged-beam technique at the SOLEIL synchrotron radiation facility in Saint-Aubin, France. High-resolution spectroscopy at nominal resolutions of 38, 56, 111, 133 meV full width at half maximum (FWHM) for Be-like and 125 meV FWHM for Li-like atomic nitrogen ions was achieved for the photon energies ranging from 410 up to 460 eV. The experimental measurements are compared with theoretical estimates from the multi-configuration Dirac-Fock, R-matrix and an empirical method. The interplay between experiment and theory enabled the identification and characterization of the strong 1s -> 2p resonances features observed in the K-shell spectra of each ion and the region around 460 eV for the 1s -> 3p resonance of the N3+ ion yielding suitable agreement with experiment.
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O'Keeffe, P., Gryzlova, E. V., Cubaynes, D., Garcia, G. A., Nahon, L., Grum-Grzhimailo, A. N., & Meyer, M. (2013). Isotopically Resolved Photoelectron Imaging Unravels Complex Atomic Autoionization Dynamics by Two-Color Resonant Ionization. PHYSICAL REVIEW LETTERS, 111(24), 243002.
Résumé: Angle-resolved electron spectroscopy in coincidence with high-resolution mass spectroscopy has been applied to study two-color resonant photoionization in atomic xenon. Separation of different isotopes enabled us to extract results for the electronic dynamics free from depolarization effects, which are generally introduced by the coupling of the electronic and nuclear angular momenta. The concerted experimental and theoretical analysis of the photoelectron angular distributions in the region of an autoionizing resonance emphasizes the strong sensitivity of the observed structures to the fine details of the treatment of the underlying dynamics.
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2012 |
Bizau, J. M., Cubaynes, D., Al Shorman, M. M., Guilbaud, S., Blancard, C., Lemaire, J., Thissen, R., Giuliani, A., Nicolas, C., & Milosavljevic, A. R. (2012). Photoionization of atomic and molecular positively charged ions. In 26TH SUMMER SCHOOL AND INTERNATIONAL SYMPOSIUM ON THE PHYSICS OF IONIZED GASES (SPIG 2012) (Vol. 399).
Résumé: We compare advantages and drawbacks of the two techniques mainly used for the experimental study of gas phase photoionization processes on ionic targets in combination with synchrotron radiation, the merged beam and ion trap. The comparison will be illustrated by recent results obtained on atomic and small molecular positively charged ions using both techniques at SOLEIL, the French synchrotron radiation facility.
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Blancard, C., Cosse, P., Faussurier, G., Bizau, J. - M., Cubaynes, D., El Hassan, N., Guilbaud, S., Al Shorman, M. M., Robert, E., Liu, X. - J., Nicolas, C., & Miron, C. (2012). L-shell photoionization of Ar+ to Ar3+ ions. PHYSICAL REVIEW A, 85(4), 043408.
Résumé: Absolute photoionization cross sections of Ar+, Ar2+, and Ar3+ ions have been measured in the 250-280 eV photon energy range. These results are compared to theoretical cross sections extracted from two new calculations we performed. They reproduce well the general behavior of the experimental spectra and the magnitude of the direct photoionization cross sections. However, the oscillator strength of the resonant structure in the spectra, dominated by 2p -> 3d transitions, is overestimated up to 80% by our calculations.
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Gharaibeh, M. F., Bizau, J. - M., Cubaynes, D., Guilbaud, S., El Hassan, N., Al Shorman, M. M., Blancard, C., & McLaughlin, B. M. (2012). K-Shell Photoionization of Singly Ionized Atomic Nitrogen. In XXVII ICPEAC Journal of Physics: Conference Series (Vol. 388).
Résumé: K-shell photoionization cross-section measurements for singly ionized atomic nitrogen made at the SOLEIL Light Source for the first time are compared with MCDF and R-matrix calculations.
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Richardson, V., Li, W. B., Kelly, T. J., Costello, J. T., Nikolopoulos, L. A. A., Duesterer, S., Cubaynes, D., & Meyer, M. (2012). Dichroism in the above-threshold two-colour photoionization of singly charged neon. JOURNAL OF PHYSICS B-ATOMIC MOLECULAR AND OPTICAL PHYSICS, 45(8), 085601.
Résumé: In this work we report on the ionization of a gaseous neon target by combining extreme ultraviolet (XUV) radiation from the Free Electron Laser in Hamburg with an intense synchronized optical laser. Applying energy-resolved photoelectron spectroscopy, the dependence of the electrons ejected from singly charged neon (Ne+) on the relative polarization of the XUV and optical laser fields was investigated. The electron spectra exhibit a strong dependence on the degree of the relative orientation of the linear polarization vectors. A quantitative analysis was undertaken using multichannel time-dependent perturbation theory in order to reproduce the magnitude of the ejected low kinetic energy electrons as a function of the relative polarization directions and explicitly taking into account the influence of the residual Ne2+ cores (D-1, P-3). It is concluded that the variation of the photoelectron spectrum with the deviation of XUV and optical field directions is mainly related to the different responses of the magnetic substates of the ejected electrons in their interaction with the laser field.
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2011 |
Bizau, J. M., Blancard, C., Coreno, M., Cubaynes, D., Dehon, C., El Hassan, N., Folkmann, F., Gharaibeh, M. F., Giuliani, A., Lemaire, J., Milosavljevic, A. R., Nicolas, C., & Thissen, R. (2011). Photoionization study of Kr+ and Xe+ ions with the combined use of a merged-beam set-up and an ion trap. JOURNAL OF PHYSICS B-ATOMIC MOLECULAR AND OPTICAL PHYSICS, 44(5), 055205.
Résumé: Photoionization cross sections of halogen-like Kr+ and Xe+ ions have been measured in the photon energy range extending up to 15 eV above the threshold. Two different devices were used, a merged-beam set-up and an ion trap. Combination of the two techniques allows for the extraction of the pure ground state ionization cross section on an absolute scale. Multiconfiguration Dirac-Fock calculations reproduce the magnitude of the direct photoionization cross sections well.
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Gharaibeh, M. F., Bizau, J. M., Cubaynes, D., Guilbaud, S., El Hassan, N., Al Shorman, M. M., Miron, C., Nicolas, C., Robert, E., Blancard, C., & McLaughlin, B. M. (2011). K-shell photoionization of singly ionized atomic nitrogen: experiment and theory. JOURNAL OF PHYSICS B-ATOMIC MOLECULAR AND OPTICAL PHYSICS, 44(17), 175208.
Résumé: Absolute cross sections for the K-shell photoionization of C-like nitrogen ions were measured by employing the ion-photon merged-beam technique at the SOLEIL synchrotron radiation facility in Saint-Aubin, France. High-resolution spectroscopy with E/Delta E approximate to 7000 was achieved with the photon energy from 388 to 430 eV scanned with a band pass of 300 meV, and the 399.4-402 eV range with 60 meV. Experimental results are compared with theoretical predictions made from the multi-configuration Dirac-Fock and R-matrix methods. The interplay between experiment and theory enabled the identification and characterization of the strong 1s -> 2p resonances observed in the spectra.
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Meyer, M., Grum-Grzhimailo, A. N., Cubaynes, D., Felfli, Z., Heinecke, E., Manson, S. T., & Zimmermann, P. (2011). Magnetic Dichroism in K-Shell Photoemission from Laser Excited Li Atoms. PHYSICAL REVIEW LETTERS, 107(21), 213001.
Résumé: Magnetic dichroism in the angular distribution has been demonstrated for single-electron photoemission from inner ns(2) subshells of gaseous atomic targets using the example of K-shell photoionization of polarized Li atoms laser prepared in the 1s(2)2p (2)P(3/2) excited state. The effect is pronounced for the conjugate shakeup and conjugate shakedown photoelectron lines, and less important, though observable, for the main and direct shakeup lines. The phenomenon is caused by configuration interaction in the final continuum state and is quantitatively described by the close-coupling R-matrix calculations.
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Milosavljevic, A. R., Nicolas, C., Lemaire, J., Dehon, C., Thissen, R., Bizau, J. - M., Refregiers, M., Nahon, L., & Giuliani, A. (2011). Photoionization of a protein isolated in vacuo. PHYSICAL CHEMISTRY CHEMICAL PHYSICS, 13(34), 15432–15436.
Résumé: Gas phase VUV single-photon photoionization spectroscopy of electrospray-produced multiply protonated cytochrome c protein ( 12 kDa) has been performed by means of coupling a linear quadrupole ion trap with a synchrotron beamline. The thresholds for the ionization of the 8+ and 11+ charge state precursors to radical 9+ and 12+ species were measured to be 12.75 +/- 0.10 and 13.51 +/- 0.10 eV, respectively.
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2009 |
Bizau, J. - M., Mosnier, J. - P., Kennedy, E. T., Cubaynes, D., Wuilleumier, F. J., Blancard, C., Champeaux, J. - P., & Folkmann, F. (2009). Photoionization of the Ne-like Si4+ ion in ground and metastable states in the 110-184-eV photon energy range. PHYSICAL REVIEW A, 79(3).
Résumé: We present measurements of the absolute photoionization cross section of the neonlike Si4+ ion over the 110-184 eV photon energy range. The measurements were performed using two independent merged-beam setups at the super-ACO and ASTRID synchrotron-radiation facilities, respectively. Signals produced in the photoionization of the 2p subshell of the Si4+ ion both from the 2p(6) S-1(0) ground state and the 2p(5)3s P-3(0,2) metastable levels were observed. Calculations of the 2p photoionization cross sections were carried out using a multi-configuration Dirac-Fock code. They give results in good agreement with the measured spectra. Comparison with other available theoretical results is also presented.
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El Hassan, N., Bizau, J. M., Blancard, C., Cosse, P., Cubaynes, D., Faussurier, G., & Folkmann, F. (2009). Photoionization cross sections of iron isonuclear sequence ions: Fe2+ to Fe6+. PHYSICAL REVIEW A, 79(3).
Résumé: We have measured the absolute photoionization cross sections of Fe2+ to Fe6+ ions in the photon energy range covering the first ionization threshold up to 160 eV. Particular interest is emphasized on the region of the 3p -> 3d excitations. The experimental data are compared to the results of calculations we have performed using a spectral opacity code, as well as to available R-matrix and one-electron calculations. It is shown that often the theoretical results tend to overestimate the intensity of the 3p -> 3d photoexcitations. An anomalously low value of the integrated oscillator strength is measured for Fe2+ ion.
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2008 |
Thissen, R., Bizau, J. M., Blancard, C., Coreno, M., Dehon, C., Franceschi, P., Giuliani, A., Lemaire, J., & Nicolas, C. (2008). Photoionization cross section of Xe(+) ion in the pure 5p(5) (2)P(3/2) ground level. PHYSICAL REVIEW LETTERS, 100(22), 223001.
Résumé: Coupling an ion trap with synchrotron radiation is shown here to be a powerful approach to measure photoionization cross sections on ionic species relaxed in their ground state. The photoionization efficiency curve of Xe(+) ions stored in a Fourier transform ion cyclotron resonance ion trap was recorded at ELETTRA in the 20-23 eV photon energy range. Absolute cross sections were derived by comparison of the photoionization yield of Xe(+) with measurements from the ASTRID merged-beam experiment. Multiconfiguration Dirac-Fock calculations were performed for the interpretation of these new data.
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First Observation of Photoelectron Spectra Emitted in the Photoionization of a Singly Charged - Ion Beam with Synchrotron Radiation, J. M. Bizau, D. Cubaynes, M. Richter, F. J. Wuilleumier, J. Obert, J.-C. Putaux, T. J. Morgan, E. Källne, S. Sorensen et A. Damany, Phys. Rev. Lett. 67, 576 (1991).