| 1. |
- Alagia, M., et al.
(författare)
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Excitation of 1S and 3S Metastable Helium Atoms to Doubly Excited States
- 2009
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Ingår i: Physical Review Letters. - 0031-9007 .- 1079-7114. ; 102:15, s. 153001-
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Tidskriftsartikel (refereegranskat)abstract
- We present spectra of triplet and singlet metastable helium atoms resonantly photoexcited to doubly excited states. The first members of three dipole-allowed 1,3Po series have been observed and their relative photoionization cross sections determined, both in the triplet (from 1s2s 3Se) and singlet (from 1s2s 1Se) manifolds. The intensity ratios are drastically different with respect to transitions from the ground state. When radiation damping is included the results for the singlets are in agreement with theory, while for triplets spin-orbit interaction must also be taken into account.
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| 2. |
- Marchenko, T., et al.
(författare)
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Potential Energy Surface Reconstruction and Lifetime Determination of Molecular Double-Core-Hole States in the Hard X-Ray Regime
- 2017
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Ingår i: Physical Review Letters. - : AMER PHYSICAL SOC. - 0031-9007 .- 1079-7114. ; 119:13
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Tidskriftsartikel (refereegranskat)abstract
- A combination of resonant inelastic x-ray scattering and resonant Auger spectroscopy provides complementary information on the dynamic response of resonantly excited molecules. This is exemplified for CH3I, for which we reconstruct the potential energy surface of the dissociative I 3d(-2) double-core-hole state and determine its lifetime. The proposed method holds a strong potential for monitoring the hard x-ray induced electron and nuclear dynamic response of core-excited molecules containing heavy elements, where ab initio calculations of potential energy surfaces and lifetimes remain challenging.
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| 3. |
- Rubensson, Jan-Erik, et al.
(författare)
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Experimental confirmation of photon-induced spin-flip transitions in helium via triplet metastable yield spectra
- 2010
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Ingår i: Physical Review A. Atomic, Molecular, and Optical Physics. - 1050-2947 .- 1094-1622. ; 81:6, s. 062510-
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Tidskriftsartikel (refereegranskat)abstract
- Doubly excited states below the N = 2 ionization threshold are populated by exciting helium atoms in a supersonic beam with monochromatized synchrotron radiation. The fluorescence decay of these states triggers a radiative cascade back to the ground state with large probability to populate long lived singlet and triplet helium metastable states. The yield of metastables is measured using a multichannel plate detector after the beam has passed a singlet-quenching discharge lamp. The variation of the yield observed with the lamp switched on or off is related to the triplet-singlet mixing of the doubly excited states.
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| 4. |
- Žitnik, M., et al.
(författare)
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Atomic two-color XUV interferometer
- 2023
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Ingår i: 2023 Conference on Lasers and Electro-Optics Europe and European Quantum Electronics Conference, CLEO/Europe-EQEC 2023. - 9798350345995
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Konferensbidrag (refereegranskat)abstract
- We extend our recently published work which demonstrated the coherent control of population of 2s21S doubly excited state in helium by tuning the interference of ω1 + ω1 and ω3 − ω1 two-photon excitation paths [1]. The maximum yield of electrons from 2s2 autoionization was observed when the two-color phase difference matched phase difference of the atomic amplitudes describing the two alternative excitation paths. A displacement of position of the maximum yield in the same reference frame therefore signals the presence of an additional phase shifting agent along any of the two paths and also provides a measure of the corresponding phase shift. This constitutes the operational principle of an atomic XUV interferometer which is comparable to the well-known RABBITT method based on using a combination of XUV and IR light pulses [2]. The work was performed at LDM beamline at the free-electron-laser facility FERMI in Trieste (Italy). The phase difference of the two components of the light pulse was set by slightly delaying the ω3 emission from the last three undulators with respect to the ω1 emission produced by the first three undulators and this was achieved by delaying the generating electron bunch by properly adjusted magnetic chicane in between the two undulator sections.
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| 5. |
- Zitnik, M., et al.
(författare)
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Interference of two-photon transitions induced by XUV light
- 2022
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Ingår i: Optica. - : Optica Publishing Group. - 2334-2536. ; 9:7, s. 692-700
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Tidskriftsartikel (refereegranskat)abstract
- The relative phase of first (omega(1)) and third harmonics (omega(3)) extreme ultraviolet light pulses was varied to control the population of the 2s(2) state in helium through the interference of omega(1) + omega(1) and omega(3) - omega(1) two-photon excitation paths. The population was monitored by observing the total electron yield due to the 2s(2) autoionization decay. Maximum yield occurs when the relative phase of the two harmonics matches the phase difference of complex atomic amplitudes governing the two excitation paths. The calculated trend of atomic phase differences agrees well with the measured data in the spectral region of the resonance, provided that time-reversed -omega(1) + omega(3) path is also taken into account. These results open the way to accessing phase differences of two-photon ionization paths involving energetically distant intermediate states and to perform interferometry in the extreme ultraviolet range by monitoring final state populations. (c) 2022 Optica Publishing Group under the terms of the Optica Open Access Publishing Agreement
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| 6. |
- Koller, Jan, et al.
(författare)
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Simulation-Based Analysis of (Reverse) Supply Chains in Circular Product-Service-Systems
- 2023
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Ingår i: Manufacturing Driving Circular Economy: Proceedings of the 18th Global Conference on Sustainable Manufacturing, October 5–7, 2022, Berlin. - Cham, Switzerland : Springer Nature Switzerland AG. - 2195-4364 .- 2195-4356. - 9783031288395 - 9783031288388 ; , s. 111-118
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Konferensbidrag (refereegranskat)abstract
- With an expected growth of global waste to 3.40 billion tonnes by 2050 and a circularity today of only 8.6% of the world, the earth's sustainable resources are being exploited beyond their regeneration capacity. Hence, it is necessary to step away from a take – make – dispose principal and transform from a linear towards a circular economy to close product cycles to optimize resource consumption and reduce waste. Product-Service-Systems (PSSs), based on multiple product life cycles combined with remanufacturing, offer a solution to close product cycles. In such PSS, the responsibility for returning, remanufacturing, and repairing used products remains with the Original Equipment Manufacturer (OEM) and increases its need in (reverse) supply chain activities. Essential factors for (reverse) supply chains are, e.g., determining the distribution network, the location of recovery facilities, the geographical dispersion of the customers, and the information flows between the different stakeholders. In this context, this work proposes a multi-method simulation model to support practitioners in determining the optimal infrastructure for storing, remanufacturing, and repairing the used products regarding economic and ecological target criteria. The applicability of the proposed approach is illustrated through a case study of a white goods manufacturing company. This case study highlights the importance of determining the optimal infrastructure in a (reverse) supply chain in PSS business models.
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| 7. |
- Lieder, Michael, et al.
(författare)
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Towards circular economy implementation in manufacturing systems using a multimethod simulation approach to link design and business strategy
- 2017
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Ingår i: The International Journal of Advanced Manufacturing Technology. - : Springer. - 0268-3768 .- 1433-3015. ; 93:5-8, s. 1953-1970
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Tidskriftsartikel (refereegranskat)abstract
- The recent circular economy movement has raised awareness and interest about untapped environmental and economic potential in the manufacturing industry. One of the crucial aspects in the implementation of circular or closed-loop manufacturing approach is the design of circular products. While it is obvious that three post-use strategies, i.e., reuse, remanufacturing, and recycling, are highly relevant to achieve loop closure, it is enormously challenging to choose “the right” strategy (if at all) during the early design stage and especially at the single component level. One reason is that economic and environmental impacts of adapting these strategies are not explicit as they vary depending on the chosen business model and associated supply chains. In this scenario, decision support is essential to motivate adaptation of regenerative design strategies. The main purpose of this paper is to provide reliable decision support at the intersection of multiple lifecycle design and business models in the circular economy context to identify effects on cost and CO2 emissions. The development of this work consists of a systematic method to quantify design effort for different circular design options through a multi-method simulation approach. The simulation model combines an agent-based product architecture and a discrete event closed-loop supply chain model. Feasibility of the model is tested using a case of a washing machine provided by Gorenje d.d. Firstly, design efforts for reuse, remanufacturing, and recycling are quantified. Secondly, cost and emissions of different design options are explored with different business model configurations. Finally, an optimization experiment is run to identify the most cost-effective combination of reused, remanufactured, and recycled components for a business model chosen on the basis of the explorative study results.
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| 8. |
- Zitnik, M, et al.
(författare)
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High resolution multiphoton spectroscopy by a tunable free-electron-laser light.
- 2014
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Ingår i: Physical Review Letters. - 1079-7114 .- 0031-9007. ; 113:19
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Tidskriftsartikel (refereegranskat)abstract
- Seeded free electron lasers theoretically have the intensity, tunability, and resolution required for multiphoton spectroscopy of atomic and molecular species. Using the seeded free electron laser FERMI and a novel detection scheme, we have revealed the two-photon excitation spectra of dipole-forbidden doubly excited states in helium. The spectral profiles of the lowest (-1,0)^{+1} ^{1}S^{e} and (0,1)^{0} ^{1}D^{e} resonances display energy shifts in the meV range that depend on the pulse intensity. The results are explained by an effective two-level model based on calculated Rabi frequencies and decay rates.
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| 9. |
- Zitnik, M., et al.
(författare)
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Resonant inelastic X-ray spectroscopy of atoms and simple molecules : Satellite features and dependence on energy detuning and photon polarization
- 2015
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Ingår i: Journal of Electron Spectroscopy and Related Phenomena. - : Elsevier BV. - 0368-2048 .- 1873-2526. ; 204, s. 356-364
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Tidskriftsartikel (refereegranskat)abstract
- We summarize recent results dealing with high resolution (resonant) X-ray spectroscopy of atomic and molecular targets in the tender X-ray energy region. We comment on advantages, new possibilities and problems related to RIXS spectroscopy with respect to the standard photoabsorption technique, where scanning the probe energy is the only option. In particular, three research areas are covered: X-ray emission mediated by energy dependent photoabsorption to multi-electron excited states, the Cl K core-hole clock studies exemplified by systematic study of chloro(fluoro)-hydrocarbon targets and the polarization dependent X-ray emission studies. Due to its spectral selectivity and simultaneous detection capability, high resolution wavelength dispersive X-ray spectroscopy has the capability to resolve structural and dynamical properties of matter within new instrumentation frontiers.
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| 10. |
- Žitnik, M., et al.
(författare)
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Two-to-one Auger decay of a double L vacancy in argon
- 2016
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Ingår i: PHYSICAL REVIEW A. - 2469-9926. ; 93:2
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Tidskriftsartikel (refereegranskat)abstract
- We have observed L-23(2)-M-3 Auger decay in argon where a double vacancy is filled by two valence electrons and a single electron is ejected from the atom. A well-resolved spectrum of these two-to-one electron transitions is compared to the result of the second-order perturbation theory and its decay branching ratio is determined.
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