Giulio D'Acunto

All Publications

• Using Iron L-Edge and Nitrogen K-Edge X-ray Absorption Spectroscopy to Improve the Understanding of the Electronic Structure of Iron Carbene Complexes. Inorganic chemistry Guo, M., Temperton, R., D'Acunto, G., Johansson, N., Jones, R., Handrup, K., Ringelband, S., Prakash, O., Fan, H., de Groot, L. H., Hlynsson, V. F., Kaufhold, S., Gordivska, O., Velásquez González, N., Wärnmark, K., Schnadt, J., Persson, P., Uhlig, J. 2024

  Abstract

  Iron-centered N-heterocyclic carbene compounds have attracted much attention in recent years due to their long-lived excited states with charge transfer (CT) character. Understanding the orbital interactions between the metal and ligand orbitals is of great importance for the rational tuning of the transition metal compound properties, e.g., for future photovoltaic and photocatalytic applications. Here, we investigate a series of iron-centered N-heterocyclic carbene complexes with +2, + 3, and +4 oxidation states of the central iron ion using iron L-edge and nitrogen K-edge X-ray absorption spectroscopy (XAS). The experimental Fe L-edge XAS data were simulated and interpreted through restricted-active space (RAS) and multiplet calculations. The experimental N K-edge XAS is simulated and compared with time-dependent density functional theory (TDDFT) calculations. Through the combination of the complementary Fe L-edge and N K-edge XAS, direct probing of the complex interplay of the metal and ligand character orbitals was possible. The σ-donating and π-accepting capabilities of different ligands are compared, evaluated, and discussed. The results show how X-ray spectroscopy, together with advanced modeling, can be a powerful tool for understanding the complex interplay of metal and ligand.

  View details for DOI 10.1021/acs.inorgchem.4c01026

  View details for PubMedID 38934422

• <i>Operando</i> study of HfO₂ atomic layer deposition on partially hydroxylated Si(111) JOURNAL OF VACUUM SCIENCE & TECHNOLOGY A Jones, R., D'Acunto, G., Shayesteh, P., Pinsard, I., Rochet, F., Bournel, F., Gallet, J., Head, A., Schnadt, J. 2024; 42 (2)

  View details for DOI 10.1116/6.0003349

  View details for Web of Science ID 001177610500003

• Time evolution of surface species during the ALD of high-k oxide on InAs SURFACES AND INTERFACES D'Acunto, G., Shayesteh, P., Kokkonen, E., de la Cruz, V., Rehman, F., Mosahebfard, Z., Lind, E., Schnadt, J., Timm, R. 2023; 39

  View details for DOI 10.1016/j.surfin.2023.102927

  View details for Web of Science ID 001014519500001

• Bimolecular Reaction Mechanism in the Amido Complex-Based Atomic Layer Deposition of HfO2 CHEMISTRY OF MATERIALS D'Acunto, G., Tsyshevsky, R., Shayesteh, P., Gallet, J., Bournel, F., Rochet, F., Pinsard, I., Timm, R., Head, A. R., Kuklja, M., Schnadt, J. 2023

  View details for DOI 10.1021/acs.chemmater.2c02947

  View details for Web of Science ID 000908819600001

• Nitrogen plasma passivation of GaAs nanowires resolved by temperature dependent photoluminescence NANO EXPRESS Irish, A., Zou, X., Barrigon, E., D'Acunto, G., Timm, R., Borgstrom, M., Yartsev, A. 2022; 3 (4)

  View details for DOI 10.1088/2632-959X/acb1cc

  View details for Web of Science ID 000928389900001

• Atomic Hydrogen Annealing of Graphene on InAs Surfaces and Nanowires: Interface and Morphology Control for Optoelectronics and Quantum Technologies ACS APPLIED NANO MATERIALS Mousavi, S., Liu, Y., D'Acunto, G., Troian, A., Caridad, J. M., Niu, Y., Zhu, L., Jash, A., Flodgren, V., Lehmann, S., Dick, K. A., Zakharov, A., Timm, R., Mikkelsen, A. 2022

  View details for DOI 10.1021/acsanm.2c03891

  View details for Web of Science ID 000890497500001

• AP-XPS Study of Ethanol Adsorption on Rutile TiO2(110) JOURNAL OF PHYSICAL CHEMISTRY C Schnadt, J., Jones, R., D'Acunto, G., Shayesteh, P., Rehman, F. 2022

  View details for DOI 10.1021/acs.jpcc.2c05389

  View details for Web of Science ID 000862378600001

• Graphene as an Adsorption Template for Studying Double Bond Activation in Catalysis JOURNAL OF PHYSICAL CHEMISTRY C Boix, V., Xu, W., D'Acunto, G., Stubbe, J., Gallo, T., Stromsheim, M., Zhu, S., Scardamaglia, M., Shavorskiy, A., Reuter, K., Andersen, M., Knudsen, J. 2022; 126 (33): 14116-14124

  Abstract

  Hydrogenated graphene (H-Gr) is an extensively studied system not only because of its capabilities as a simplified model system for hydrocarbon chemistry but also because hydrogenation is a compelling method for Gr functionalization. However, knowledge of how H-Gr interacts with molecules at higher pressures and ambient conditions is lacking. Here we present experimental and theoretical evidence that room temperature O2 exposure at millibar pressures leads to preferential removal of H dimers on H-functionalized graphene, leaving H clusters on the surface. Our density functional theory (DFT) analysis shows that the removal of H dimers is the result of water or hydrogen peroxide formation. For water formation, we show that the two H atoms in the dimer motif attack one end of the physisorbed O2 molecule. Moreover, by comparing the reaction pathways in a vacuum with the ones on free-standing graphene and on the graphene/Ir(111) system, we find that the main role of graphene is to arrange the H atoms in geometrical positions, which facilitates the activation of the O=O double bond.

  View details for DOI 10.1021/acs.jpcc.2c02293

  View details for Web of Science ID 000848573500001

  View details for PubMedID 36060283

  View details for PubMedCentralID PMC9425632

• Following the Kinetics of Undercover Catalysis with APXPS and the Role of Hydrogen as an Intercalation Promoter ACS CATALYSIS Boix, V., Scardamaglia, M., Gallo, T., D'Acunto, G., Stromsheim, M., Cavalca, F., Zhu, S., Shavorskiy, A., Schnadt, J., Knudsen, J. 2022; 12 (16): 9897-9907

  View details for DOI 10.1021/acscatal.2c00803

  View details for Web of Science ID 000844650800001

• Hydrogen plasma enhanced oxide removal on GaSb planar and nanowire surfaces APPLIED SURFACE SCIENCE Liu, Y., Yngman, S., Troian, A., D'Acunto, G., Jonsson, A., Svensson, J., Mikkelsen, A., Wernersson, L., Timm, R. 2022; 593

  View details for DOI 10.1016/j.apsusc.2022.153336

  View details for Web of Science ID 000796157800004

• In situ methods: discoveries and challenges: general discussion FARADAY DISCUSSIONS Arrigo, R., Aureau, D., Bhatt, P., Buckingham, M. A., Counter, J. C., D'Acunto, G., Davies, P. R., Evans, D., Flavell, W. R., Gibson, J. S., Guan, S., Held, G., Isaacs, M., Kahk, J., Kastorp, C. P., Kersell, H., Krizan, A., Large, A. I., Lindsay, R., Lischner, J., Lomker, P., Morgan, D., Nemsak, S., Nilsson, A., Payne, D., Reed, B. P., Renault, O., Rupprechter, G., Shard, A. G., Shozi, M., Silly, M. G., Skinner, W. J., Solal, F., Stoerzinger, K. A., Suzer, S., Velasco Velez, J., Walker, M., Weatherup, R. S. 2022; 236 (0): 219-266

  View details for DOI 10.1039/d2fd90025d

  View details for Web of Science ID 000840427700001

  View details for PubMedID 35968885

• Role of Temperature, Pressure, and Surface Oxygen Migration in the Initial Atomic Layer Deposition of HfO2 on Anatase TiO2 (101) JOURNAL OF PHYSICAL CHEMISTRY C D'Acunto, G., Jones, R., Ramirez, L., Shayesteh, P., Kokkonen, E., Rehman, F., Lim, F., Bournel, F., Gallet, J., Timm, R., Schnadt, J. 2022

  View details for DOI 10.1021/acs.jpcc.2c02683

  View details for Web of Science ID 000867449600001

• Oxygen relocation during HfO2 ALD on InAs FARADAY DISCUSSIONS D'Acunto, G., Kokkonen, E., Shayesteh, P., Boix, V., Rehman, F., Mosahebfard, Z., Lind, E., Schnadt, J., Timm, R. 2022; 236 (0): 71-85

  Abstract

  Atomic layer deposition (ALD) is one of the backbones for today's electronic device fabrication. A critical property of ALD is the layer-by-layer growth, which gives rise to the atomic-scale accuracy. However, the growth rate - or growth per cycle - can differ significantly depending on the type of system, molecules used, and several other experimental parameters. Typically, ALD growth rates are constant in subsequent ALD cycles, making ALD an outstanding deposition technique. However, contrary to this steady-state - when the ALD process can be entirely decoupled from the substrate on which the material is grown - the deposition's early stage does not appear to follow the same kinetics, chemistry, and growth rate. Instead, it is to a large extent determined by the surface composition of the substrate. Here, we present evidence of oxygen relocation from the substrate-based oxide, either the thermal or native oxide of InAs, to the overlayer of HfO2 in the initial ALD phase. This phenomenon enables control of the thickness of the initial ALD layer by controlling the surface conditions of the substrate prior to ALD. On the other hand, we observe a complete removal of the native oxide from InAs already during the first ALD half-cycle, even if the thickness of the oxide layer exceeds one monolayer, together with a self-limiting thickness of the ALD layer of a maximum of one monolayer of HfO2. These observations not only highlight several limitations of the widely used ligand exchange model, but they also give promise for a better control of the industrially important self-cleaning effect of III-V semiconductors, which is crucial for future generation high-speed MOS.

  View details for DOI 10.1039/d1fd00116g

  View details for Web of Science ID 000790349100001

  View details for PubMedID 35506440

• Time-Resolved APXPS with Chemical Potential Perturbations: Recent Developments at the MAX IV Laboratory Synchrotron Radiation News Shavorskiy, A., Kokkonnen, E., Redekop, E., D'Acunto, G., Schnadt, J., Knudsen, J. 2022; 35 (3)

  View details for DOI 10.1080/08940886.2022.2082166

• Resonant X-ray photo-oxidation of light-harvesting iron (II/III) N-heterocyclic carbene complexes SCIENTIFIC REPORTS Temperton, R. H., Guo, M., D'Acunto, G., Johansson, N., Rosemann, N. W., Prakash, O., Warnmark, K., Schnadt, J., Uhlig, J., Persson, P. 2021; 11 (1): 22144

  Abstract

  Two photoactive iron N-heterocyclic carbene complexes [Formula: see text] and [Formula: see text], where btz is 3,3'-dimethyl-1,1'-bis(p-tolyl)-4,4'-bis(1,2,3-triazol-5-ylidene) and bpy is 2,2'-bipyridine, have been investigated by Resonant Photoelectron Spectroscopy (RPES). Tuning the incident X-ray photon energy to match core-valence excitations provides a site specific probe of the electronic structure properties and ligand-field interactions, as well as information about the resonantly photo-oxidised final states. Comparing measurements of the Fe centre and the surrounding ligands demonstrate strong mixing of the Fe [Formula: see text] levels with occupied ligand [Formula: see text] orbitals but weak mixing with the corresponding unoccupied ligand orbitals. This highlights the importance of [Formula: see text]-accepting and -donating considerations in ligand design strategies for photofunctional iron carbene complexes. Spin-propensity is also observed as a final-state effect in the RPES measurements of the open-shell [Formula: see text] complex. Vibronic coupling is evident in both complexes, where the energy dispersion hints at a vibrationally hot final state. The results demonstrate the significant impact of the iron oxidation state on the frontier electronic structure and highlights the differences between the emerging class of [Formula: see text] photosensitizers from those of more traditional [Formula: see text] complexes.

  View details for DOI 10.1038/s41598-021-01509-7

  View details for Web of Science ID 000718023200017

  View details for PubMedID 34772983

  View details for PubMedCentralID PMC8590020

• Thickness and composition of native oxides and near-surface regions of Ni superalloys JOURNAL OF ALLOYS AND COMPOUNDS Larsson, A., D'Acunto, G., Vorobyova, M., Abbondanza, G., Lienert, U., Hegedus, Z., Preobrajenski, A., Merte, L. R., Eidhagen, J., Delblanc, A., Pan, J., Lundgren, E. 2022; 895

  View details for DOI 10.1016/j.jallcom.2021.162657

  View details for Web of Science ID 000720143000005

• Stroboscopic operando spectroscopy of the dynamics in heterogeneous catalysis by event-averaging NATURE COMMUNICATIONS Knudsen, J., Gallo, T., Boix, V., Stromsheim, M., D'Acunto, G., Goodwin, C., Wallander, H., Zhu, S., Soldemo, M., Lomker, P., Cavalca, F., Scardamaglia, M., Degerman, D., Nilsson, A., Amann, P., Shavorskiy, A., Schnadt, J. 2021; 12 (1): 6117

  Abstract

  Heterogeneous catalyst surfaces are dynamic entities that respond rapidly to changes in their local gas environment, and the dynamics of the response is a decisive factor for the catalysts' action and activity. Few probes are able to map catalyst structure and local gas environment simultaneously under reaction conditions at the timescales of the dynamic changes. Here we use the CO oxidation reaction and a Pd(100) model catalyst to demonstrate how such studies can be performed by time-resolved ambient pressure photoelectron spectroscopy. Central elements of the method are cyclic gas pulsing and software-based event-averaging by image recognition of spectral features. A key finding is that at 3.2 mbar total pressure a metallic, predominantly CO-covered metallic surface turns highly active for a few seconds once the O2:CO ratio becomes high enough to lift the CO poisoning effect before mass transport limitations triggers formation of a √5 oxide.

  View details for DOI 10.1038/s41467-021-26372-y

  View details for Web of Science ID 000710514300002

  View details for PubMedID 34675205

  View details for PubMedCentralID PMC8531341

• Gas Pulse-X-Ray Probe Ambient Pressure Photoelectron Spectroscopy with Submillisecond Time Resolution ACS APPLIED MATERIALS & INTERFACES Shavorskiy, A., D'Acunto, G., de la Cruz, V., Scardamaglia, M., Zhu, S., Temperton, R. H., Schnadt, J., Knudsen, J. 2021; 13 (40): 47629-47641

  View details for DOI 10.1021/acsami.1c13590

  View details for Web of Science ID 000709458200029

• Area-selective Electron-beam induced deposition of Amorphous-BNx on graphene APPLIED SURFACE SCIENCE Boix, V., Struzzi, C., Gallo, T., Johansson, N., D'Acunto, G., Yong, Z., Zakharov, A., Li, Z., Schnadt, J., Mikkelsen, A., Knudsen, J. 2021; 557

  View details for DOI 10.1016/j.apsusc.2021.149806

  View details for Web of Science ID 000651208700006

• Tuning oxygen vacancies and resistive switching properties in ultra-thin HfO2 RRAM via TiN bottom electrode and interface engineering APPLIED SURFACE SCIENCE Yong, Z., Persson, K., Ram, M., D'Acunto, G., Liu, Y., Benter, S., Pan, J., Li, Z., Borg, M., Mikkelsen, A., Wernersson, L., Timm, R. 2021; 551

  View details for DOI 10.1016/j.apsusc.2021.149386

  View details for Web of Science ID 000674654300031

• HIPPIE: a new platform for ambient-pressure X-ray photoelectron spectroscopy at the MAX IV Laboratory JOURNAL OF SYNCHROTRON RADIATION Zhu, S., Scardamaglia, M., Kundsen, J., Sankari, R., Tarawneh, H., Temperton, R., Pickworth, L., Cavalca, F., Wang, C., Tissot, H., Weissenrieder, J., Hagman, B., Gustafson, J., Kaya, S., Lindgren, F., Kallquist, I., Maibach, J., Hahlin, M., Boix, V., Gallo, T., Rehman, F., D'Acunto, G., Schnadt, J., Shavorskiy, A. 2021; 28: 624-636

  Abstract

  HIPPIE is a soft X-ray beamline on the 3 GeV electron storage ring of the MAX IV Laboratory, equipped with a novel ambient-pressure X-ray photoelectron spectroscopy (APXPS) instrument. The endstation is dedicated to performing in situ and operando X-ray photoelectron spectroscopy experiments in the presence of a controlled gaseous atmosphere at pressures up to 30 mbar [1 mbar = 100 Pa] as well as under ultra-high-vacuum conditions. The photon energy range is 250 to 2200 eV in planar polarization and with photon fluxes >1012 photons s-1 (500 mA ring current) at a resolving power of greater than 10000 and up to a maximum of 32000. The endstation currently provides two sample environments: a catalysis cell and an electrochemical/liquid cell. The former allows APXPS measurements of solid samples in the presence of a gaseous atmosphere (with a mixture of up to eight gases and a vapour of a liquid) and simultaneous analysis of the inlet/outlet gas composition by online mass spectrometry. The latter is a more versatile setup primarily designed for APXPS at the solid-liquid (dip-and-pull setup) or liquid-gas (liquid microjet) interfaces under full electrochemical control, and it can also be used as an open port for ad hoc-designed non-standard APXPS experiments with different sample environments. The catalysis cell can be further equipped with an IR reflection-absorption spectrometer, allowing for simultaneous APXPS and IR spectroscopy of the samples. The endstation is set up to easily accommodate further sample environments.

  View details for DOI 10.1107/S160057752100103X

  View details for Web of Science ID 000626355600029

  View details for PubMedID 33650575

  View details for PubMedCentralID PMC7941293

• Comparative study of copper oxidation protection with graphene and hexagonal boron nitride CARBON Scardamaglia, M., Boix, V., D'Acunto, G., Struzzi, C., Reckinger, N., Chen, X., Shivayogimath, A., Booth, T., Knudsen, J. 2021; 171: 610-617

  View details for DOI 10.1016/j.carbon.2020.09.021

  View details for Web of Science ID 000598371500064

• Atomic Layer Deposition of Hafnium Oxide on InAs: Insight from Time-Resolved in Situ Studies ACS APPLIED ELECTRONIC MATERIALS D'Acunto, G., Troian, A., Kokkonen, E., Rehman, F., Liu, Y., Yngman, S., Yong, Z., McKibbin, S. R., Gallo, T., Lind, E., Schnadt, J., Timm, R. 2020; 2 (12): 3915-3922

  View details for DOI 10.1021/acsaelm.0c00775

  View details for Web of Science ID 000603295000016

• Polarization Effects of Transversal and Longitudinal Optical Phonons in Bundles of Multiwall Carbon Nanotubes JOURNAL OF PHYSICAL CHEMISTRY C Ripanti, F., D'Acunto, G., Betti, M., Mariani, C., Bittencourt, C., Postorino, P. 2019; 123 (32): 20013-20019

  View details for DOI 10.1021/acs.jpcc.9b02638

  View details for Web of Science ID 000481568900087

• Channelling and induced defects at ion-bombarded aligned multiwall carbon nanotubes CARBON D'Acunto, G., Ripanti, F., Postorino, P., Betti, M., Scardamaglia, M., Bittencourt, C., Mariani, C. 2018; 139: 768-775

  View details for DOI 10.1016/j.carbon.2018.07.032

  View details for Web of Science ID 000446063100089