| 1. |
- Albinsson, David, 1990, et al.
(författare)
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Operando detection of single nanoparticle activity dynamics inside a model pore catalyst material
- 2020
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Ingår i: Science advances. - : American Association for the Advancement of Science (AAAS). - 2375-2548. ; 6:25
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Tidskriftsartikel (refereegranskat)abstract
- Nanoconfinement in porous catalysts may induce reactant concentration gradients inside the pores due to local conversion. This leads to inefficient active material use since parts of the catalyst may be trapped in an inactive state. Experimentally, these effects remain unstudied due to material complexity and required high spatial resolution. Here, we have nanofabricated quasi-two-dimensional mimics of porous catalysts, which combine the traits of nanofluidics with single particle plasmonics and online mass spectrometry readout. Enabled by single particle resolution at operando conditions during CO oxidation over a Cu model catalyst, we directly visualize reactant concentration gradient formation due to conversion on single Cu nanoparticles inside the “model pore” and how it dynamically controls oxidation state-and, thus, activity-of particles downstream. Our results provide a general framework for single particle catalysis in the gas phase and highlight the importance of single particle approaches for the understanding of complex catalyst materials.
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| 2. |
- Albinsson, David, 1990, et al.
(författare)
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Shedding light on CO oxidation surface chemistry on single Pt catalyst nanoparticles inside a nanofluidic model pore
- 2021
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Ingår i: ACS Catalysis. - : American Chemical Society (ACS). - 2155-5435. ; 11:4, s. 2021-2033
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Tidskriftsartikel (refereegranskat)abstract
- Investigating a catalyst under relevant application conditions is experimentally challenging and parameters like reaction conditions in terms of temperature, pressure, and reactant mixing ratios, as well as catalyst design, may significantly impact the obtained experimental results. For Pt catalysts widely used for the oxidation of carbon monoxide, there is keen debate on the oxidation state of the surface at high temperatures and at/above atmospheric pressure, as well as on the most active surface state under these conditions. Here, we employ a nanoreactor in combination with single-particle plasmonic nanospectroscopy to investigate individual Pt catalyst nanoparticles localized inside a nanofluidic model pore during carbon monoxide oxidation at 2 bar in the 450-550 K temperature range. As a main finding, we demonstrate that our single-particle measurements effectively resolve a kinetic phase transition during the reaction and that each individual particle has a unique response. Based on spatially resolved measurements, we furthermore observe how reactant concentration gradients formed due to conversion inside the model pore give rise to position-dependent kinetic phase transitions of the individual particles. Finally, employing extensive electrodynamics simulations, we unravel the surface chemistry of the individual Pt nanoparticles as a function of reactant composition and find strongly temperature-dependent Pt-oxide formation and oxygen spillover to the SiO2 support as the main processes. These results therefore support the existence of a Pt surface oxide in the regime of high catalyst activity and demonstrate the possibility to use plasmonic nanospectroscopy in combination with nanofluidics as a tool for in situ studies of individual catalyst particles.
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| 3. |
- Aumayr, Friedrich, et al.
(författare)
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Roadmap on photonic, electronic and atomic collision physics : III. Heavy particles
- 2019
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Ingår i: Journal of Physics B. - : IOP Publishing. - 0953-4075 .- 1361-6455. ; 52:17
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Tidskriftsartikel (refereegranskat)abstract
- We publish three Roadmaps on photonic, electronic and atomic collision physics in order to celebrate the 60th anniversary of the ICPEAC conference. Roadmap III focusses on heavy particles: with zero to relativistic speeds. Modern theoretical and experimental approaches provide detailed insight into the wide range of many-body interactions involving projectiles and targets of varying complexity ranging from simple atoms, through molecules and clusters, complex biomolecules and nanoparticles to surfaces and crystals. These developments have been driven by technological progress and future developments will expand the horizon of the systems that can be studied. This Roadmap aims at looking back along the road, explaining the evolution of the field, and looking forward, collecting nineteen contributions from leading scientists in the field.
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| 4. |
- Bieron, Jacek, et al.
(författare)
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Ab initio MCDHF calculations of electron-nucleus interactions
- 2015
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Ingår i: Physica Scripta. - : Institute of Physics Publishing (IOPP). - 0031-8949 .- 1402-4896. ; 90:5
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Tidskriftsartikel (refereegranskat)abstract
- We present recent advances in the development of atomic ab initio multiconfiguration Dirac– Hartree–Fock theory, implemented in the GRASP relativistic atomic structure code. For neutral atoms, the deviations of properties calculated within the Dirac–Hartree–Fock (DHF) method (based on independent particle model of an atomic cloud) are usually dominated by electron correlation effects, i.e. the non-central interactions of individual electrons. We present the recent advances in accurate calculations of electron correlation effects in small, medium, and heavy neutral atoms. We describe methods of systematic development of multiconfiguration expansions leading to systematic, controlled improvement of the accuracy of the ab initio calculations. These methods originate from the concept of the complete active space (CAS) model within the DHF theory, which, at least in principle, permits fully relativistic calculations with full account of electron correlation effects. The calculations within the CAS model on currently available computer systems are feasible only for very light systems. For heavier atoms or ions with more than a few electrons, restrictions have to be imposed on the multiconfiguration expansions. We present methods and tools, which are designed to extend the numerical calculations in a controlled manner, where multiconfiguration expansions account for all leading electron correlation effects. We show examples of applications of the GRASP code to calculations of hyperfine structure constants, but the code may be used for calculations of arbitrary bound-state atomic properties. In recent years it has been applied to calculations of atomic and ionic spectra (transition energies and rates), to determinations of nuclear electromagnetic moments, as well as to calculations related to interactions of bound electrons with nuclear electromagnetic moments leading to violations of discrete symmetries.
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| 5. |
- Bieron, Jacek, et al.
(författare)
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Multiconfiguration Dirac-Hartree-Fock calculations of the electric dipole moment of radium induced by the nuclear Schiff moment
- 2009
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Ingår i: Physical Review A. Atomic, Molecular, and Optical Physics. - : American Physical Society. - 1050-2947 .- 1094-1622. ; 80:1
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Tidskriftsartikel (refereegranskat)abstract
- The multiconfiguration Dirac-Hartree-Fock theory has been employed to calculate the electric dipole moment of the 7s6d 3D2 state of radium induced by the nuclear Schiff moment. The results are dominated by valence and core-valence electron correlation effects. We show that the correlation effects can be evaluated in a converged series of multiconfiguration expansions.
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| 6. |
- Carette, Thomas, et al.
(författare)
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Electronic factors for isotope shifts
- 2013
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Ingår i: Book of abstracts. - : Institute of Modern Physics, Chinese Academy of Sciences.
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Synopsis Progresses have been made in the ab initio calculation of the electronic factors contributing to the mass and eld isotope shifts of atomic spectral lines. We will illustrate these progresses and underline the current limitations.
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| 7. |
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| 8. |
- D'Amico, Valeria, et al.
(författare)
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Advanced interference management in ARTIST4G: Interference Avoidance
- 2010
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Ingår i: European Wireless Technology Conference, Paris, France, September 2010. - 9782874870187 ; , s. 21-24
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Konferensbidrag (refereegranskat)abstract
- This paper gives an overview of the objectives and current research activities on interference avoidance in the EC funded research project ARTIST4G. It is the main objective of the ARTIST4G Work Package 1 (WP1), to build forward on the 3GPP LTE Release 8 baseline, proposing a novel fair mobile broadband technological framework in which to design innovative, practical, scalable and cost-effective interference avoidance solutions. This paper provides an overview of the fundamental classes of innovations studied in ARTIST4G Work Package 1 (WP1) and presents some performance results obtained by means of numerical simulations and test-bed measurements run in the field.
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| 9. |
- D’Amico, Valeria, et al.
(författare)
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EU FP7 INFSO-ICT-247223 ARTIST4G, D1.1 Definitions and architecture requirements for supporting interference avoidance techniques
- 2010
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- It is the main objective of the ARTIST4G Work Package 1 (WP1), to design innovative interference avoidance solutions by means of transmitter signal processing, scheduling and/or cross layer techniques. Such an approach will enable to identify optimal strategies also taking into account the practical implications on the real system. The major impacts of the WP1 innovations on the radio access network and on the mobile system interfaces, together with constraints due to practical implementations, will be analyzed in this deliverable. This deliverable will be a reference for the work in ARTIST4G Work Package 4 (WP4).A set of guiding questions used to precise the requirements for WP4 has been considered for each new cooperation/coordination functionality. Answers to these questions are provided in this deliverable by grouping the different classes of WP1 innovations into 4 categories with similar requirements on the radio access architecture. For each question, current, expected, minimum and maximum targets of the requirement will be given, helping to ensure that the range of all possible values for all the innovations are taken into account.
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| 10. |
- D’Amico, Valeria, et al.
(författare)
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EU FP7 INFSO-ICT-247223 ARTIST4G, D1.2 Innovative advanced signal processing algorithms for interference avoidance
- 2010
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- This document provides an overview of the proposed innovations and activities in Task 1.1 of Work Package 1 (WP1) of the ARTIST4G project, related to interference avoidance. Focus is on the technical approaches applicable at the physical layer, which are grouped into four different classes of innovations related to single-cell multi-user MIMO schemes, multi-cell multi-user MIMOschemes, advanced 3D beamforming and enabling functionalities. Descriptions of the proposed innovations are given including basic ideas, potential of performance, simulation results, realization options and possible implementation restrictions.
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