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Publications (10 of 144) Show all publications
Kaur, H., Thuermer, S., Gholami, S., Credidio, B., Trinter, F., Vasconcelos, D., . . . Björneholm, O. (2025). Boosting aerosol surface effects: strongly enhanced cooperative surface propensity of atmospherically relevant organic molecular ions in aqueous solution. Atmospheric Chemistry And Physics, 25(6), 3503-3518
Open this publication in new window or tab >>Boosting aerosol surface effects: strongly enhanced cooperative surface propensity of atmospherically relevant organic molecular ions in aqueous solution
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2025 (English)In: Atmospheric Chemistry And Physics, ISSN 1680-7316, E-ISSN 1680-7324, Vol. 25, no 6, p. 3503-3518Article in journal (Refereed) Published
Abstract [en]

The effects of atmospheric aerosols are key uncertainties in climate models. One reason is the complex aerosol composition which includes a relatively large fraction of organics. Another reason is the small size of aerosols, which makes surface effects and processes important. These two factors make surface-active organics relevant for atmospheric aerosols, as they can affect crucial processes, such as chemical aging and water accommodation, as well as properties such as the surface tension, which drives droplet formation. Two exemplary types of atmospherically relevant organics are carboxylic acids and alkyl amines, and often both are found together within aerosols. In the most atmospherically significant pH range, these exist as alkyl-carboxylate ions and alkyl-ammonium ions. Using liquid-jet photoelectron spectroscopy, tuned to high surface sensitivity, we measured the alkyl-carboxylate anions and the alkyl-ammonium cations of alkyl chain lengths of 1 to 6 carbon atoms, both as single-component and mixed-component aqueous solutions. This enabled us to systematically study how their surface propensity is affected by the length of the alkyl chains and how cooperative ion-ion interactions result in strongly increased surface propensity. An exponential increase in surface propensity is found for the single-species solutions, with cooperative solute-solute effects in mixed solutions of 1 : 1 molar ratio drastically increasing the number of molecules present at the solutions' surfaces up to a factor of several hundred. This cooperative surface propensity is shown to strongly affect the amounts of organics at the surface. These changes can significantly influence radiative forcing via aerosol growth, cloud condensation nuclei activity, and aerosol chemical aging. Our results demonstrate the principal feasibility of a more advanced input of molecular details for creating parameterized descriptions of aerosol surface composition needed to properly account for their impacts in climate models.

Place, publisher, year, edition, pages
Copernicus Publications, 2025
National Category
Physical Chemistry
Identifiers
urn:nbn:se:uu:diva-554510 (URN)10.5194/acp-25-3503-2025 (DOI)001451152800001 ()2-s2.0-105000937995 (Scopus ID)
Funder
EU, Horizon 2020, 883759Swedish Research Council, 2023-04346
Available from: 2025-04-14 Created: 2025-04-14 Last updated: 2025-04-14Bibliographically approved
Vetelainen, O., Babayan, M., Pihlava, L., Abid, A. R., Kivimaki, A., Kukk, E., . . . Diaz-Tendero, S. (2025). Hydrogen migration reactions via low internal energy pathways in aminobenzoic acid dications. Physical Chemistry, Chemical Physics - PCCP, 27(18), 9884-9894
Open this publication in new window or tab >>Hydrogen migration reactions via low internal energy pathways in aminobenzoic acid dications
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2025 (English)In: Physical Chemistry, Chemical Physics - PCCP, ISSN 1463-9076, E-ISSN 1463-9084, Vol. 27, no 18, p. 9884-9894Article in journal (Refereed) Published
Abstract [en]

Hydrogen migration is a ubiquitous phenomenon upon dissociation of organic molecules. Here we investigate the formation of a H3O+ fragment after core-level photoionization and Auger decay in aminobenzoic acid molecules - a process that requires the migration of at least two hydrogen atoms. Using photoelectron-photoion coincidence spectroscopy, the formation of a H3O+ fragment is observed to be more probable in ortho-aminobenzoic acid than in meta- and para-aminobenzoic acid. Energy-resolved Auger electron-photoion coincidences are measured for the ortho-isomer to investigate the internal energy dependence of the fragmentation channels, most notably of those producing H3O+. The corresponding fragmentation channels and their mechanisms are investigated by exploring the potential energy surface with ab initio quantum chemistry methods and molecular dynamics simulations. Excited-state modeling of dicationic ortho-aminobenzoic acid is used to interpret features in the Auger spectra and identify the electronic states contributing to the signals in the Auger electron photoion coincidence map. We show that populating low-energy excited states of the dication is sufficient to trigger hydrogen migration and produce H3O+ efficiently.

Place, publisher, year, edition, pages
Royal Society of Chemistry, 2025
National Category
Atom and Molecular Physics and Optics
Identifiers
urn:nbn:se:uu:diva-556695 (URN)10.1039/d5cp00415b (DOI)001477324200001 ()40293246 (PubMedID)2-s2.0-105003871861 (Scopus ID)
Funder
EU, Horizon 2020Swedish Research CouncilVinnovaSwedish Research Council Formas, MCIN/AEI/10.13039/501100011033Swedish Research Council Formas, CEX2023-001316-M
Available from: 2025-05-26 Created: 2025-05-26 Last updated: 2025-05-26Bibliographically approved
Wahlund, J.-E., Bergman, J. E. S., Åhlén, L., Puccio, W., Cecconi, B., Kasaba, Y., . . . Miyoshi, Y. (2025). The Radio & Plasma Wave Investigation (RPWI) for the JUpiter ICy moons Explorer (JUICE). Space Science Reviews, 221(1), Article ID 1.
Open this publication in new window or tab >>The Radio & Plasma Wave Investigation (RPWI) for the JUpiter ICy moons Explorer (JUICE)
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2025 (English)In: Space Science Reviews, ISSN 0038-6308, E-ISSN 1572-9672, Vol. 221, no 1, article id 1Article, review/survey (Refereed) Published
Abstract [en]

The Radio & Plasma Wave Investigation (RPWI) onboard the ESA JUpiter ICy moons Explorer (JUICE) is described in detail. The RPWI provides an elaborate set of state-of-the-art electromagnetic fields and cold plasma instrumentation, including active sounding with the mutual impedance and Langmuir probe sweep techniques, where several different types of sensors will sample the thermal plasma properties, including electron and ion densities, electron temperature, plasma drift speed, the near DC electric fields, and electric and magnetic signals from various types of phenomena, e.g., radio and plasma waves, electrostatic acceleration structures, induction fields etc. A full wave vector, waveform, polarization, and Poynting flux determination will be achieved. RPWI will enable characterization of the Jovian radio emissions (including goniopolarimetry) up to 45 MHz, has the capability to carry out passive radio sounding of the ionospheric densities of icy moons and employ passive sub-surface radar measurements of the icy crust of these moons. RPWI can also detect micrometeorite impacts, estimate dust charging, monitor the spacecraft potential as well as the integrated EUV flux. The sensors consist of four 10 cm diameter Langmuir probes each mounted on the tip of 3 m long booms, a triaxial search coil magnetometer and a triaxial radio antenna system both mounted on the 10.6 m long MAG boom, each with radiation resistant pre-amplifiers near the sensors. There are three receiver boards, two Digital Processing Units (DPU) and two Low Voltage Power Supply (LVPS) boards in a box within a radiation vault at the centre of the JUICE spacecraft. Together, the integrated RPWI system can carry out an ambitious planetary science investigation in and around the Galilean icy moons and the Jovian space environment. Some of the most important science objectives and instrument capabilities are described here. RPWI focuses, apart from cold plasma studies, on the understanding of how, through electrodynamic and electromagnetic coupling, the momentum and energy transfer occur with the icy Galilean moons, their surfaces and salty conductive sub-surface oceans. The RPWI instrument is planned to be operational during most of the JUICE mission, during the cruise phase, in the Jovian magnetosphere, during the icy moon flybys, and in particular Ganymede orbit, and may deliver data from the near surface during the final crash orbit.

Place, publisher, year, edition, pages
Springer, 2025
Keywords
JUICE, RPWI, Ganymede, Europa, Callisto, Jupiter
National Category
Fusion, Plasma and Space Physics Astronomy, Astrophysics and Cosmology
Identifiers
urn:nbn:se:uu:diva-546945 (URN)10.1007/s11214-024-01110-0 (DOI)001378473600001 ()
Funder
Swedish National Space BoardUppsala University
Available from: 2025-01-13 Created: 2025-01-13 Last updated: 2025-01-13Bibliographically approved
Muchova, E., Gopakumar, G., Unger, I., Ohrwall, G., Ceolin, D., Trinter, F., . . . Björneholm, O. (2024). Attosecond formation of charge-transfer-to-solvent states of aqueous ions probed using the core-hole-clock technique. Nature Communications, 15(1), Article ID 8903.
Open this publication in new window or tab >>Attosecond formation of charge-transfer-to-solvent states of aqueous ions probed using the core-hole-clock technique
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2024 (English)In: Nature Communications, E-ISSN 2041-1723, Vol. 15, no 1, article id 8903Article in journal (Refereed) Published
Abstract [en]

Charge transfer between molecules lies at the heart of many chemical processes. Here, we focus on the ultrafast electron dynamics associated with the formation of charge-transfer-to-solvent (CTTS) states following X-ray absorption in aqueous solutions of Na+, Mg2+, and Al3+ ions. To explore the formation of such states in the aqueous phase, liquid-jet photoemission spectroscopy is employed. Using the core-hole-clock method, based on Auger-Meitner (AM) decay upon 1s excitation or ionization of the respective ions, upper limits are estimated for the metal-atom electron delocalization times to the neighboring water molecules. These delocalization processes represent the first steps in the formation of hydrated electrons, which are determined to take place on a timescale ranging from several hundred attoseconds (as) below the 1s ionization threshold to only 20 as far above the 1s ionization threshold. The decrease in the delocalization times as a function of the photon energy is continuous. This indicates that the excited electrons remain in the vicinity of the studied ions even above the ionization threshold, i.e., metal-ion electronic resonances associated with the CTTS state manifolds are formed. The three studied isoelectronic ions exhibit quantitative differences in their electron energetics and delocalization times, which are linked to the character of the respective excited states. The authors investigate the X-ray-induced electron dynamics, on the sub-femtosecond timescale, of hydrated Na+, Mg2+, and Al3+ ions providing insights into the ultrafast charge-transfer processes in aqueous environments.

Place, publisher, year, edition, pages
Springer Nature, 2024
National Category
Atom and Molecular Physics and Optics
Identifiers
urn:nbn:se:uu:diva-541526 (URN)10.1038/s41467-024-52740-5 (DOI)001337260300003 ()39406706 (PubMedID)
Funder
Swedish Research Council, 2018-07152Swedish Research Council, 2018-00740Vinnova, 2018-04969Swedish Research Council Formas, 2019-02496EU, Horizon 2020, 883759-AQUACHIRALSwedish Research Council, VR 2023-04346
Available from: 2024-11-04 Created: 2024-11-04 Last updated: 2024-11-04Bibliographically approved
Mikkelä, M.-H., Marnauza, M., Hetherington, C. J., Wallenberg, R., Mårsell, E., Liu, Y.-P., . . . Tchaplyguine, M. (2024). Bismuth-oxide nanoparticles: study in a beam and as deposited. Physical Chemistry, Chemical Physics - PCCP, 26(13), 10369-10381
Open this publication in new window or tab >>Bismuth-oxide nanoparticles: study in a beam and as deposited
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2024 (English)In: Physical Chemistry, Chemical Physics - PCCP, ISSN 1463-9076, E-ISSN 1463-9084, Vol. 26, no 13, p. 10369-10381Article in journal (Refereed) Published
Abstract [en]

Bi2O3 is a promising material for solid-oxide fuel cells (SOFC) due to the high ionic conductivity of some phases. The largest value is reached for its δ-phase, but it is normally stable at temperatures too high for SOFC operation, while nanostructured oxide is believed to have more suitable stabilization temperature. However, to manufacture such a material with a controlled chemical composition is a challenging task. In this work, we investigated the fabrication of nanostructured Bi2O3 films formed by deposition of free Bi-oxide nanoparticles created in situ. The particle-production method was based on reactive sputtering and vapour aggregation. Depending on the fabrication conditions, the nanoparticles contained either a combination of Bi–metal and Bi-oxide, or only Bi-oxide. Prior to deposition, the free particles were probed in the beam – by synchrotron-based photoelectron spectroscopy (PES), which allowed assessing their composition "on the-fly". The nanoparticle films obtained after deposition were studied by PES, scanning electron microscopy, transmission electron microscopy, and electron diffraction. The films' chemical composition, grain dimensions, and crystal structure were probed. Our analysis suggests that our method produced Bi-oxide films in more than one polymorph of Bi2O3.

Place, publisher, year, edition, pages
Royal Society of Chemistry, 2024
National Category
Materials Chemistry
Identifiers
urn:nbn:se:uu:diva-530040 (URN)10.1039/d4cp00376d (DOI)001186875800001 ()38502136 (PubMedID)
Funder
Swedish Research CouncilKnut and Alice Wallenberg FoundationEU, FP7, Seventh Framework Programme, 226716Carl Tryggers foundation Lund University
Available from: 2024-06-03 Created: 2024-06-03 Last updated: 2024-06-03Bibliographically approved
Mosaferi, M., Ceolin, D., Rueff, J.-P., Selles, P., Odelius, M., Björneholm, O., . . . Carniato, S. (2024). Fingerprint of Dipole Moment Orientation of Water Molecules in Cu2+ Aqueous Solution Probed by X-ray Photoelectron Spectroscopy. Journal of the American Chemical Society, 146(14), 9836-9850
Open this publication in new window or tab >>Fingerprint of Dipole Moment Orientation of Water Molecules in Cu2+ Aqueous Solution Probed by X-ray Photoelectron Spectroscopy
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2024 (English)In: Journal of the American Chemical Society, ISSN 0002-7863, E-ISSN 1520-5126, Vol. 146, no 14, p. 9836-9850Article in journal (Refereed) Published
Abstract [en]

The electronic structure and geometrical organization of aqueous Cu2+ have been investigated by using X-ray photoelectron spectroscopy (XPS) at the Cu L-edge combined with state-of-the-art ab initio molecular dynamics and a quantum molecular approach designed to simulate the Cu 2p X-ray photoelectron spectrum. The calculations offer a comprehensive insight into the origin of the main peak and satellite features. It is illustrated how the energy drop of the Cu 3d levels (≈7 eV) following the creation of the Cu 2p core hole switches the nature of the highest singly occupied molecular orbitals (MOs) from the dominant metal to the dominant MO nature of water. It is particularly revealed how the repositioning of the Cu 3d levels induces the formation of new bonding (B) and antibonding (AB) orbitals, from which shakeup mechanisms toward the relaxed H-SOMO operate. As highlighted in this study, the appearance of the shoulder near the main peak corresponds to the characteristic signature of shakeup intraligand (1a1 → H-SOMO(1b1)) excitations in water, providing insights into the average dipole moment distribution (≈36°) of the first-shell water molecules surrounding the metal ion and its direct impact on the broadening of the satellite. It is also revealed that the main satellite at 8 eV from the main peak corresponds to (metal/1b2 → H-SOMO(1b1) of water) excitations due to a bonding/antibonding (B/AB) interaction of Cu 3d levels with the deepest valence O2p/H1s 1b2 orbitals of water. This finding underscores the sensitivity of XPS to the electronic structure and orientation of the nearest water molecules around the central ion.

Place, publisher, year, edition, pages
American Chemical Society (ACS), 2024
National Category
Theoretical Chemistry
Identifiers
urn:nbn:se:uu:diva-530041 (URN)10.1021/jacs.3c14570 (DOI)001193912900001 ()38545903 (PubMedID)
Available from: 2024-06-04 Created: 2024-06-04 Last updated: 2024-06-04Bibliographically approved
Svensson, P., Schwob, L., Grånäs, O., Unger, I., Björneholm, O., Timneanu, N., . . . Berholts, M. (2024). Heavy element incorporation in nitroimidazole radiosensitizers: molecular-level insights into fragmentation dynamics. Physical Chemistry, Chemical Physics - PCCP, 26(2), 770-779
Open this publication in new window or tab >>Heavy element incorporation in nitroimidazole radiosensitizers: molecular-level insights into fragmentation dynamics
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2024 (English)In: Physical Chemistry, Chemical Physics - PCCP, ISSN 1463-9076, E-ISSN 1463-9084, Vol. 26, no 2, p. 770-779Article in journal (Refereed) Published
Abstract [en]

The present study investigates the photofragmentation behavior of iodine-enhanced nitroimidazole-based radiosensitizer model compounds in their protonated form using near-edge X-ray absorption mass spectrometry and quantum mechanical calculations. These molecules possess dual functionality: improved photoabsorption capabilities and the ability to generate species that are relevant to cancer sensitization upon photofragmentation. Four samples were investigated by scanning the generated fragments in the energy regions around C 1s, N 1s, O 1s, and I 3d-edges with a particular focus on NO2+ production. The experimental summed ion yield spectra are explained using the theoretical near-edge X-ray absorption fine structure spectrum based on density functional theory. Born-Oppenheimer-based molecular dynamics simulations were performed to investigate the fragmentation processes.

Place, publisher, year, edition, pages
Royal Society of Chemistry, 2024
National Category
Atom and Molecular Physics and Optics
Identifiers
urn:nbn:se:uu:diva-522697 (URN)10.1039/d3cp03800a (DOI)001090175100001 ()37888897 (PubMedID)
Funder
Swedish Research Council, 2019-03935Swedish Research Council, 2017-05128Swedish Research Council, 2018-00740Swedish Foundation for Strategic ResearchSwedish National Infrastructure for Computing (SNIC), 2022/1-36Swedish National Infrastructure for Computing (SNIC), 2022/22-597
Available from: 2024-02-08 Created: 2024-02-08 Last updated: 2024-02-08Bibliographically approved
Söderström, J., Ghosh, A., Kjellsson, L., Ekholm, V., Tokushima, T., Såthe, C., . . . Gel’mukhanov, F. (2024). Parity violation in resonant inelastic soft x-ray scattering at entangled core holes. Science Advances, 10(7)
Open this publication in new window or tab >>Parity violation in resonant inelastic soft x-ray scattering at entangled core holes
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2024 (English)In: Science Advances, E-ISSN 2375-2548, Vol. 10, no 7Article in journal (Refereed) Published
Abstract [en]

Resonant inelastic x-ray scattering (RIXS) is a major method for investigation of electronic structure and dynamics, with applications ranging from basic atomic physics to materials science. In RIXS applied to inversion-symmetric systems, it has generally been accepted that strict parity selectivity applies in the sub–kilo–electron volt region. In contrast, we show that the parity selection rule is violated in the RIXS spectra of the free homonuclear diatomic O2 molecule. By analyzing the spectral dependence on scattering angle, we demonstrate that the violation is due to the phase difference in coherent scattering at the two atomic sites, in analogy with Young’s double-slit experiment. The result also implies that the interpretation of x-ray absorption spectra for inversion symmetric molecules in this energy range must be revised.

Place, publisher, year, edition, pages
American Association for the Advancement of Science (AAAS), 2024
National Category
Atom and Molecular Physics and Optics
Identifiers
urn:nbn:se:uu:diva-524047 (URN)10.1126/sciadv.adk3114 (DOI)001189022400006 ()2-s2.0-85185243654 (Scopus ID)
Funder
Swedish Foundation for Strategic Research, RIF14-0064Swedish Research Council, 2021-04521Swedish Research Council, 2019-03470Swedish Research Council, 2021-04017Swedish Research Council, 2022-06725Swedish Research Council, 2018-05973Swedish Energy Agency, 50745-1
Available from: 2024-02-28 Created: 2024-02-28 Last updated: 2025-02-04Bibliographically approved
Pihlava, L., Svensson, P., Kukk, E., Kooser, K., De Santis, E., Tonisoo, A., . . . Berholts, M. (2024). Shell-dependent photofragmentation dynamics of a heavy-atom-containing bifunctional nitroimidazole radiosensitizer. Physical Chemistry, Chemical Physics - PCCP, 26(11), 8879-8890
Open this publication in new window or tab >>Shell-dependent photofragmentation dynamics of a heavy-atom-containing bifunctional nitroimidazole radiosensitizer
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2024 (English)In: Physical Chemistry, Chemical Physics - PCCP, ISSN 1463-9076, E-ISSN 1463-9084, Vol. 26, no 11, p. 8879-8890Article in journal (Refereed) Published
Abstract [en]

Radiation therapy uses ionizing radiation to break chemical bonds in cancer cells, thereby causing DNA damage and leading to cell death. The therapeutic effectiveness can be further increased by making the tumor cells more sensitive to radiation. Here, we investigate the role of the initial halogen atom core hole on the photofragmentation dynamics of 2-bromo-5-iodo-4-nitroimidazole, a potential bifunctional radiosensitizer. Bromine and iodine atoms were included in the molecule to increase the photoionization cross-section of the radiosensitizer at higher photon energies. The fragmentation dynamics of the molecule was studied experimentally in the gas phase using photoelectron-photoion-photoion coincidence spectroscopy and computationally using Born-Oppenheimer molecular dynamics. We observed significant changes between shallow core (I 4d, Br 3d) and deep core (I 3d) ionization in fragment formation and their kinetic energies. Despite the fact, that the ions ejected after deep core ionization have higher kinetic energies, we show that in a cellular environment, the ion spread is not much larger, keeping the damage well-localized. A study on photodissociation dynamics of 2-bromo-5-iodo-nitroimidazole - a model radiosensitizer - using coincidence spectroscopy and computational methods.

Place, publisher, year, edition, pages
Royal Society of Chemistry, 2024
National Category
Atom and Molecular Physics and Optics Physical Chemistry
Identifiers
urn:nbn:se:uu:diva-528495 (URN)10.1039/d4cp00367e (DOI)001175892400001 ()38426309 (PubMedID)
Funder
Swedish Research Council, 2023-04346Swedish Research Council, 2018-00740
Available from: 2024-05-22 Created: 2024-05-22 Last updated: 2024-05-22Bibliographically approved
Dupuy, R., Buttersack, T., Trinter, F., Richter, C., Gholami, S., Björneholm, O., . . . Bluhm, H. (2024). The solvation shell probed by resonant intermolecular Coulombic decay. Nature Communications, 15(1), Article ID 6926.
Open this publication in new window or tab >>The solvation shell probed by resonant intermolecular Coulombic decay
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2024 (English)In: Nature Communications, E-ISSN 2041-1723, Vol. 15, no 1, article id 6926Article in journal (Refereed) Published
Abstract [en]

Molecules involved in solvation shells have properties differing from those of the bulk solvent, which can in turn affect reactivity. Among key properties of these molecules are their nature and electronic structure. Widely used tools to characterize this type of property are X-ray-based spectroscopies, which, however, usually lack the capability to selectively probe the solvation-shell molecules. A class of X-ray triggered "non-local" processes has the recognized potential to provide this selectivity. Intermolecular Coulombic decay (ICD) and related processes involve neighbouring molecules in the decay of the X-ray-excited target, and are thus naturally sensitive to its immediate environment. Applying electron spectroscopy to aqueous solutions, we explore the resonant flavours of ICD and demonstrate how it can inform on the first solvation shell of excited solvated cations. One particular ICD process turns out to be a potent marker of the formation of ion pairs. Another gives a direct access to the electron binding energies of the water molecules in the first solvation shell, a quantity previously elusive to direct measurements. The resonant nature of the processes makes them readily measurable, providing powerful new spectroscopic tools. X-ray triggered non-local processes, such as Intermolecular Coulombic Decay, are shown here to selectively probe solvation-shell molecules in solution and provide new information on their electronic structure and on ion-pair formation.

Place, publisher, year, edition, pages
Nature Publishing Group, 2024
National Category
Physical Chemistry Condensed Matter Physics Theoretical Chemistry
Identifiers
urn:nbn:se:uu:diva-537871 (URN)10.1038/s41467-024-51417-3 (DOI)001291270300025 ()39138192 (PubMedID)
Funder
EU, Horizon 2020, 883759Swedish Research Council, 2023-04346
Available from: 2024-09-12 Created: 2024-09-12 Last updated: 2024-09-12Bibliographically approved
Projects
X-ray antennas for improved radiotherapy [2023-04346_VR]; Uppsala University
Organisations
Identifiers
ORCID iD: ORCID iD iconorcid.org/0000-0002-7307-5404

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