Experimental and theoretical 2p core-level spectra of size-selected gas-phase aluminum and silicon cluster cations: chemical shifts, geometric structure, and coordination-dependent screening

Walter, Michael; Vogel, M.; Zamudio-Bayer, Vicente; Lindblad, Rebecka; Reichenbach, Thomas; Hirsch, Konstantin; Langenberg, A.; Rittmann, J.; Kulesza, Alexander; Mitrić, Roland; Moseler, Michael; Möller, Thomas; Issendorff, Bernd von; Lau, J. Tobias

doi:10.1039/c8cp07169a

Cited by 13 publications

(13 citation statements)

References 85 publications

(169 reference statements)

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“…Special importance is attracted by the absorptions in the low-energy regime starting from 3.5 eV corresponding to the clusters with 16, 17, 18, 20, 21, and to some extent 26 atoms. For the species in this size range prolate structures are observed experimentally − ,,− and also indicated quantum chemically. ,,,,− Interestingly the Mie–Gans theory as well predicts enhanced absorption for p-Si starting from 3.3 eV for prolate structures. In this sense, the increased absorption in the clusters with 16, 17, 18, 20, 21, and 26 atoms might be seen as an indication for the exceptional prolate growth habit of the intermediate-sized Si clusters.…”

Section: Resultsmentioning

confidence: 73%

Optical Properties of Si_n⁺ (n = 6–100) Clusters: The Approach to Bulk Behavior

Lehr

Jäger

2019

J. Phys. Chem. C

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Photoabsorption spectra of isolated Si 6−100 + clusters are presented in the energy range of ℏω = 1.9−5.4 eV. By measuring the absolute photodissociation cross sections, this work attempts to bridge the gap between the optical properties of few-atom-sized silicon clusters to the well-studied regime of nanoparticles and the condensed matter. This is demonstrated by probing the effective optical band gaps in dependence of the size of the silicon clusters. From comparison with the corresponding bulk properties predicted by Mie theory, structural transitions between spherical and prolate clusters as well as quantum confinement effects for larger clusters are stressed. The impact of the dissociation threshold on the measured absorption spectra is considered carefully.

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Section: Resultsmentioning

confidence: 73%

Optical Properties of Si_n⁺ (n = 6–100) Clusters: The Approach to Bulk Behavior

Lehr

Jäger

2019

J. Phys. Chem. C

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“…The systematic GO of the targeted Zn y O x clusters (with y = 3–9 and x = 0 – y ) was performed using the EA implemented by Vilhelmsen and Hammer , in the Atomic Simulation Environment package, which has been successfully used in previous GO studies of gas-phase and supported metal ,,, and oxide clusters, steps, and intercalated graphene structures. , This algorithm begins by generating a set (population) of random starting structures (candidates), which are subsequently mutated or paired in order to generate new candidate structures. The algorithm decides if each new structure is included in the population by evaluating its fitness, which depends on the potential energy of the locally relaxed candidate.…”

Section: Methods and Computational Detailsmentioning

confidence: 99%

Effects of Gas-Phase Conditions and Particle Size on the Properties of Cu(111)-Supported Zn_yO_x Particles Revealed by Global Optimization and Ab Initio Thermodynamics

et al. 2019

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The characterization of the interaction between nano or sub-nanoparticles with a support nowadays increasingly relies on computational modeling by means of the density functional theory calculations. These provide valuable atomic-detail understanding of the structure and energetics of supported clusters, but it is still challenging to find (or design) structural models that are representative of real systems in terms of size, structure, and composition. In this study, we have applied an extensive and systematic approach combining global optimization based on an evolutionary algorithm with atomistic ab initio thermodynamics for finding stable structures of a relevant material for catalytic methanol synthesis: Cu(111)-supported Zn y O x clusters. We identify the ZnO3 motif as the elementary building block of such clusters, on which we recently have investigated the full catalytic process for methanol synthesis [Reichenbach, T.; Mondal, K.; Jäger, M.; Vent-Schmidt, T.; Himmel, D.; Dybbert, V.; Bruix, A.; Krossing, I.; Walter, M.; Moseler, M. J. Catal., 2018, 360, 168–174]. With the collection of global minima of Cu(111)-supported Zn y O x clusters resulting from this large-scale global optimization effort, we assess the effect of size, gas-phase conditions, and support interactions on the phase diagrams, reactivity, and structural properties of the Zn y O x particles. We find moderate size-effects that are mostly related to the differences in stable Zn/O ratios of the identified global minima and to the formation of different sites in larger clusters. In contrast, large differences in the oxidation state of the clusters as defined by the gas-phase conditions significantly affect the geometry, electronic structure, and reactivity of the Zn y O x particles. This highlights the importance of thoroughly sampling structures with different stoichiometry and appropriately assessing their stability using a detailed thermodynamics analysis.

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“…Possible contribution to the NEXAFS spectrum resulting from X-ray absorption of the fragments is estimated to be less than 1% . Even though sequential valence photoionization has been observed in the VUV photon energy range when studying large clusters using this ion trap setup, it has not been observed for core level photoionization in the soft X-ray range. , …”

Section: Methodsmentioning

confidence: 83%

Section: Methodsmentioning

confidence: 99%

“…12 Even though sequential valence photoionization has been observed in the VUV photon energy range when studying large clusters using this ion trap setup, 15 it has not been observed for core level photoionization in the soft X-ray range. 16,17 Computational Methods. We have performed simulations of the photon-absorption process as captured by the NEXAFS spectrum using the ORCA 18 code.…”

Section: ■ Introductionmentioning

confidence: 99%

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X-ray Induced Fragmentation of Protonated Cystine

et al. 2022

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We demonstrate site-specific X-ray induced fragmentation across the sulfur L-edge of protonated cystine, the dimer of the amino acid cysteine. Ion yield NEXAFS were performed in the gas phase using electrospray ionization (ESI) in combination with an ion trap. The interpretation of the sulfur L-edge NEXAFS spectrum is supported by Restricted Open-Shell Configuration Interaction (ROCIS) calculations. The fragmentation pathway of triply charged cystine ions was modeled by Molecular Dynamics (MD) simulations. We have deduced a possible pathway of fragmentation upon excitation and ionization of S 2p electrons. The disulfide bridge breaks for resonant excitation at lower photon energies but remains intact upon higher energy resonant excitation and upon ionization of S 2p. The larger fragments initially formed subsequently break into smaller fragments.

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Experimental and theoretical 2p core-level spectra of size-selected gas-phase aluminum and silicon cluster cations: chemical shifts, geometric structure, and coordination-dependent screening

Abstract: 2p binding energies of size-selected clusters reveal bonding motifs and help to assign new ground state geometries.

Cited by 13 publications

References 85 publications

Optical Properties of Si_n⁺ (n = 6–100) Clusters: The Approach to Bulk Behavior

Optical Properties of Si_n⁺ (n = 6–100) Clusters: The Approach to Bulk Behavior

Effects of Gas-Phase Conditions and Particle Size on the Properties of Cu(111)-Supported Zn_yO_x Particles Revealed by Global Optimization and Ab Initio Thermodynamics

X-ray Induced Fragmentation of Protonated Cystine

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Experimental and theoretical 2p core-level spectra of size-selected gas-phase aluminum and silicon cluster cations: chemical shifts, geometric structure, and coordination-dependent screening

Abstract: 2p binding energies of size-selected clusters reveal bonding motifs and help to assign new ground state geometries.

Cited by 13 publications

References 85 publications

Optical Properties of Sin+ (n = 6–100) Clusters: The Approach to Bulk Behavior

Optical Properties of Sin+ (n = 6–100) Clusters: The Approach to Bulk Behavior

Effects of Gas-Phase Conditions and Particle Size on the Properties of Cu(111)-Supported ZnyOx Particles Revealed by Global Optimization and Ab Initio Thermodynamics

X-ray Induced Fragmentation of Protonated Cystine

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Optical Properties of Si_n⁺ (n = 6–100) Clusters: The Approach to Bulk Behavior

Optical Properties of Si_n⁺ (n = 6–100) Clusters: The Approach to Bulk Behavior

Effects of Gas-Phase Conditions and Particle Size on the Properties of Cu(111)-Supported Zn_yO_x Particles Revealed by Global Optimization and Ab Initio Thermodynamics