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Marlton SJP, Liu C, Bieske EJ. Bond dissociation energy of FeCr+ determined through threshold photodissociation in a cryogenic ion trap. J Chem Phys 2024; 160:034301. [PMID: 38226822 DOI: 10.1063/5.0188157] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2023] [Accepted: 12/20/2023] [Indexed: 01/17/2024] Open
Abstract
The bond dissociation energy of FeCr+ is measured using resonance enhanced photodissociation spectroscopy in a cryogenic ion trap. The onset for FeCr+ → Fe + Cr+ photodissociation occurs well above the lowest Cr+(6S, 3d5) + Fe(5D, 3d64s2) dissociation limit. In contrast, the higher energy FeCr+ → Fe+ + Cr photodissociation process exhibits an abrupt onset at the energy of the Cr(7S, 3d54s1) + Fe+(6D, 3d64s1) limit, enabling accurate dissociation energies to be extracted: D(Fe-Cr+) = 1.655 ± 0.006 eV and D(Fe+-Cr) = 2.791 ± 0.006 eV. The measured D(Fe-Cr+) bond energy is 10%-20% larger than predictions from accompanying CAM (Coulomb Attenuated Method)-B3LYP and NEVPT2 and coupled cluster singles, doubles, and perturbative triples electronic structure calculations, which give D(Fe-Cr+) = 1.48, 1.40, and 1.35 eV, respectively. The study emphasizes that an abrupt increase in the photodissociation yield at threshold requires that the molecule possesses a dense manifold of optically accessible, coupled electronic states adjacent to the dissociation asymptote. This condition is not met for the lowest Cr+(6S, 3d5) + Fe(5D, 3d64s2) dissociation limit of FeCr+ but is satisfied for the higher energy Cr(7S, 3d54s1) + Fe+(6D, 3d64s1) dissociation limit.
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Affiliation(s)
- Samuel J P Marlton
- School of Chemistry, The University of Melbourne, Melbourne, Victoria 3010, Australia
| | - Chang Liu
- School of Chemistry, The University of Melbourne, Melbourne, Victoria 3010, Australia
| | - Evan J Bieske
- School of Chemistry, The University of Melbourne, Melbourne, Victoria 3010, Australia
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Delcey MG, Lindblad R, Timm M, Bülow C, Zamudio-Bayer V, von Issendorff B, Lau JT, Lundberg M. Soft x-ray signatures of ionic manganese-oxo systems, including a high-spin manganese(V) complex. Phys Chem Chem Phys 2022; 24:3598-3610. [DOI: 10.1039/d1cp03667j] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Manganese-oxo species catalyze key reactions, including C–H bond activation or dioxygen formation in natural photosynthesis. To better understand relevant reaction intermediates, we characterize electronic states and geometric structures of [MnOn]+...
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Couto RC, Hua W, Lindblad R, Kjellsson L, Sorensen SL, Kubin M, Bülow C, Timm M, Zamudio-Bayer V, von Issendorff B, Söderström J, Lau JT, Rubensson JE, Ågren H, Carravetta V. Breaking inversion symmetry by protonation: experimental and theoretical NEXAFS study of the diazynium ion, N 2H . Phys Chem Chem Phys 2021; 23:17166-17176. [PMID: 34346432 DOI: 10.1039/d1cp02002a] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
As an example of symmetry breaking in NEXAFS spectra of protonated species we present a high resolution NEXAFS spectrum of protonated dinitrogen, the diazynium ion N2H+. By ab initio calculations we show that the spectrum consists of a superposition of two nitrogen 1s absorption spectra, each including a π* band, and a nitrogen 1s to H+ charge transfer band followed by a weak irregular progression of high energy excitations. Calculations also show that, as an effect of symmetry breaking by protonation, the π* transitions are separated by 0.23 eV, only slightly exceeding the difference in the corresponding dark (symmetry forbidden) and bright (symmetry allowed) core excitations of neutral N2. By DFT and calculations and vibrational analysis, the complex π* excitation band of N2H+ is understood as due to the superposition of the significantly different vibrational progressions of excitations from terminal and central nitrogen atoms, both leading to bent final state geometries. We also show computationally that the electronic structure of the charge transfer excitation smoothly depends on the nitrogen-proton distance and that there is a clear extension of the spectra going from infinity to close nitrogen-proton distance where fine structures show some, although not fully detailed, similarities. An interesting feature of partial localization of the nitrogen core orbitals, with a strong, non-monotonous, variation with nitrogen-proton distance could be highlighted. Specific effects could be unraveled when comparing molecular cation NEXAFS spectra, as represented by recently recorded spectra of N2+ and CO+, and spectra of protonated molecules as represented here by the N2H+ ion. Both types containing rich physical effects not represented in NEXAFS of neutral molecules because of the positive charge, whereas protonation also breaks the symmetry. The effect of the protonation on dinitrogen can be separated in charge, which extends the high-energy part of the spectrum, and symmetry-breaking, which is most clearly seen in the low-energy π* transition.
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Affiliation(s)
- Rafael C Couto
- Department of Theoretical Chemistry and Biology, School of Chemistry, Biotechnology and Health, Royal Institute of Technology, SE-106 91, Stockholm, Sweden.
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Maganas D, Kowalska JK, Van Stappen C, DeBeer S, Neese F. Mechanism of L 2,3-edge x-ray magnetic circular dichroism intensity from quantum chemical calculations and experiment-A case study on V (IV)/V (III) complexes. J Chem Phys 2020; 152:114107. [PMID: 32199419 DOI: 10.1063/1.5129029] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
In this work, we present a combined experimental and theoretical study on the V L2,3-edge x-ray absorption (XAS) and x-ray magnetic circular dichroism (XMCD) spectra of VIVO(acac)2 and VIII(acac)3 prototype complexes. The recorded V L2,3-edge XAS and XMCD spectra are richly featured in both V L3 and L2 spectral regions. In an effort to predict and interpret the nature of the experimentally observed spectral features, a first-principles approach for the simultaneous prediction of XAS and XMCD spectra in the framework of wavefunction based ab initio methods is presented. The theory used here has previously been formulated for predicting optical absorption and MCD spectra. In the present context, it is applied to the prediction of the V L2,3-edge XAS and XMCD spectra of the VIVO(acac)2 and VIII(acac)3 complexes. In this approach, the spin-free Hamiltonian is computed on the basis of the complete active space configuration interaction (CASCI) in conjunction with second order N-electron valence state perturbation theory (NEVPT2) as well as the density functional theory (DFT)/restricted open configuration interaction with singles configuration state functions based on a ground state Kohn-Sham determinant (ROCIS/DFT). Quasi-degenerate perturbation theory is then used to treat the spin-orbit coupling (SOC) operator variationally at the many particle level. The XAS and XMCD transitions are computed between the relativistic many particle states, considering their respective Boltzmann populations. These states are obtained from the diagonalization of the SOC operator along with the spin and orbital Zeeman operators. Upon averaging over all possible magnetic field orientations, the XAS and XMCD spectra of randomly oriented samples are obtained. This approach does not rely on the validity of low-order perturbation theory and provides simultaneous access to the calculation of XMCD A, B, and C terms. The ability of the method to predict the XMCD C-term signs and provide access to the XMCD intensity mechanism is demonstrated on the basis of a generalized state coupling mechanism based on the type of the excitations dominating the relativistically corrected states. In the second step, the performance of CASCI, CASCI/NEVPT2, and ROCIS/DFT is evaluated. The very good agreement between theory and experiment has allowed us to unravel the complicated XMCD C-term mechanism on the basis of the SOC interaction between the various multiplets with spin S' = S, S ± 1. In the last step, it is shown that the commonly used spin and orbital sum rules are inadequate in interpreting the intensity mechanism of the XAS and XMCD spectra of the VIVO(acac)2 and VIII(acac)3 complexes as they breakdown when they are employed to predict their magneto-optical properties. This conclusion is expected to hold more generally.
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Affiliation(s)
- Dimitrios Maganas
- Max-Planck-Institut für Kohlenforschung, Kaiser-Wilhelm-Platz 1, 45470 Mülheim an der Ruhr, Germany
| | - Joanna K Kowalska
- Max Planck Institute for Chemical Energy Conversion, Stiftstrasse 34-36, 45470 Mülheim an der Ruhr, Germany
| | - Casey Van Stappen
- Max Planck Institute for Chemical Energy Conversion, Stiftstrasse 34-36, 45470 Mülheim an der Ruhr, Germany
| | - Serena DeBeer
- Max Planck Institute for Chemical Energy Conversion, Stiftstrasse 34-36, 45470 Mülheim an der Ruhr, Germany
| | - Frank Neese
- Max-Planck-Institut für Kohlenforschung, Kaiser-Wilhelm-Platz 1, 45470 Mülheim an der Ruhr, Germany
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Couto RC, Kjellsson L, Ågren H, Carravetta V, Sorensen SL, Kubin M, Bülow C, Timm M, Zamudio-Bayer V, von Issendorff B, Lau JT, Söderström J, Rubensson JE, Lindblad R. The carbon and oxygen K-edge NEXAFS spectra of CO+. Phys Chem Chem Phys 2020; 22:16215-16223. [DOI: 10.1039/d0cp02207a] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
We present and analyze high resolution near edge X-ray absorption fine structure (NEXAFS) spectra of CO+ at the carbon and oxygen K-edges.
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Zamudio-Bayer V, Hirsch K, Langenberg A, Ławicki A, Terasaki A, von Issendorff B, Lau JT. Large orbital magnetic moments of small, free cobalt cluster ions Co[Formula: see text] with n [Formula: see text]. J Phys Condens Matter 2018; 30:464002. [PMID: 30270848 DOI: 10.1088/1361-648x/aae54a] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
The size dependent electronic structure and separate spin and orbital magnetic moments of free Co[Formula: see text] ([Formula: see text]) cluster ions have been investigated by x-ray absorption and x-ray magnetic circular dichroism spectroscopy in a cryogenic ion trap. A very large orbital magnetic moment of [Formula: see text] per atom was determined for Co[Formula: see text], which is one order of magnitude larger than in the bulk metal. Large orbital magnetic moments per atom of ≈1 [Formula: see text] were also found for Co[Formula: see text], Co[Formula: see text], and Co[Formula: see text]. The orbital contribution to the total magnetic moment shows a non-monotonic cluster size dependence: The orbital contribution increases from a local minimum at n = 2 to a local maximum at n = 5 and then decreases with increasing cluster size. The 3d spin magnetic moment per atom is nearly constant and is solely defined by the number of 3d holes which shows that the 3d majority spin states are fully occupied, that is, 3d hole spin polarization is 100%.
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Affiliation(s)
- V Zamudio-Bayer
- Abteilung für Hochempfindliche Röntgenspektroskopie, Helmholtz-Zentrum Berlin für Materialien und Energie, Albert-Einstein-Straße 15, 12489 Berlin, Germany. Institut für Methoden und Instrumentierung der Forschung mit Synchrotronstrahlung, Helmholtz-Zentrum Berlin für Materialien und Energie, Albert-Einstein-Straße 15, 12489 Berlin, Germany. Physikalisches Institut, Universität Freiburg, Hermann-Herder-Straße 3, 79104 Freiburg, Germany
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Godehusen K, Richter T, Zimmermann P, Wernet P. Iron L-Edge Absorption Spectroscopy of Iron Pentacarbonyl and Ferrocene in the Gas Phase. J Phys Chem A 2017; 121:66-72. [PMID: 27992225 DOI: 10.1021/acs.jpca.6b10399] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
Fe L-edge X-ray absorption spectra of gas-phase iron pentacarbonyl and ferrocene measured in total-ion yield mode are reported. Comparison to previously published spectra of free iron atoms and gaseous iron chloride demonstrates how the interplay of local atomic multiplet effects and orbital interactions in the metal-ligand bonds varies for the different systems. We find changes in the degree of metal-ligand covalency to be reflected in the measured 2p absorption onset. Orbital- or state-specific fragmentation is furthermore investigated in iron pentacarbonyl and ferrocene by analyzing the partial-ion-yield spectra at the Fe L-edge. Strong dependence of the yields of different fragments is observed in ferrocene in contrast to iron pentacarbonyl. This difference is attributed to the different degrees to which the 2p core hole is screened in the two systems and to which charge is rearranged in the Auger final states. We provide experimental benchmark spectra for new ab initio approaches for calculating metal L-edge absorption spectra of metal complexes.
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Affiliation(s)
- Kai Godehusen
- Helmholtz-Zentrum Berlin , Hahn-Meitner-Platz 1, 14109 Berlin, Germany
| | - Tobias Richter
- European Spallation Source , Ole Maaløes Vej 3, 2200 Copenhagen, Denmark
| | - Peter Zimmermann
- Technische Universität Berlin , Hardenbergstraße 36, 10623 Berlin, Germany
| | - Philippe Wernet
- Institute for Methods and Instrumentation for Synchrotron Radiation Research, Helmholtz-Zentrum Berlin für Materialien und Energie GmbH , Albert-Einstein-Straße 15, 12489 Berlin, Germany
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Abstract
The Φ9/24 ground state of the Ni2+ diatomic molecular cation is determined experimentally from temperature and magnetic-field-dependent x-ray magnetic circular dichroism spectroscopy in a cryogenic ion trap, where an electronic and rotational temperature of 7.4±0.2 K was reached by buffer gas cooling of the molecular ion. The contribution of the spin dipole operator to the x-ray magnetic circular dichroism spin sum rule amounts to 7Tz=0.17±0.06μB per atom, approximately 11% of the spin magnetic moment. We find that, in general, homonuclear diatomic molecular cations of 3d transition metals seem to adopt maximum spin magnetic moments in their electronic ground states.
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Affiliation(s)
- V Zamudio-Bayer
- Institut für Methoden und Instrumentierung der Forschung mit Synchrotronstrahlung, Helmholtz-Zentrum Berlin für Materialien und Energie, Albert-Einstein-Straße 15, 12489 Berlin, Germany
| | - R Lindblad
- Institut für Methoden und Instrumentierung der Forschung mit Synchrotronstrahlung, Helmholtz-Zentrum Berlin für Materialien und Energie, Albert-Einstein-Straße 15, 12489 Berlin, Germany
| | - C Bülow
- Institut für Methoden und Instrumentierung der Forschung mit Synchrotronstrahlung, Helmholtz-Zentrum Berlin für Materialien und Energie, Albert-Einstein-Straße 15, 12489 Berlin, Germany
| | - G Leistner
- Institut für Methoden und Instrumentierung der Forschung mit Synchrotronstrahlung, Helmholtz-Zentrum Berlin für Materialien und Energie, Albert-Einstein-Straße 15, 12489 Berlin, Germany
| | - A Terasaki
- Cluster Research Laboratory, Toyota Technological Institute, 717-86 Futamata, Ichikawa, Chiba 272-0001, Japan
| | - B V Issendorff
- Physikalisches Institut, Universität Freiburg, Stefan-Meier-Straße 21, 79104 Freiburg, Germany
| | - J T Lau
- Institut für Methoden und Instrumentierung der Forschung mit Synchrotronstrahlung, Helmholtz-Zentrum Berlin für Materialien und Energie, Albert-Einstein-Straße 15, 12489 Berlin, Germany
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Akin ST, Zamudio-Bayer V, Duanmu K, Leistner G, Hirsch K, Bülow C, Ławicki A, Terasaki A, Issendorff BV, Truhlar DG, Lau JT, Duncan MA. Size-Dependent Ligand Quenching of Ferromagnetism in Co 3(benzene) n+ Clusters Studied with X-ray Magnetic Circular Dichroism Spectroscopy. J Phys Chem Lett 2016; 7:4568-4575. [PMID: 27779876 DOI: 10.1021/acs.jpclett.6b01839] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Cobalt-benzene cluster ions of the form Co3(bz)n+ (n = 0-3) were produced in the gas phase, mass-selected, and cooled in a cryogenic ion trap held at 3-4 K. To explore ligand effects on cluster magnetic moments, these species were investigated with X-ray absorption spectroscopy (XAS) and X-ray magnetic circular dichroism (XMCD) spectroscopy. XMCD spectra yield both the spin and orbital angular momenta of these clusters. Co3+ has a spin magnetic moment of μS = 6 μB and an orbital magnetic moment of μL = 3 μB. Co3(bz)+ and Co3(bz)2+ complexes were found to have spin and orbital magnetic moments identical to the values for ligand-free Co3+. However, coordination of the third benzene to form Co3(bz)3+ completely quenches the high spin state of the system. Density functional theory calculations elucidate the spin states of the Co3(bz)n+ species as a function of the number of attached benzene ligands, explaining the transition from septet to singlet for n = 0 → 3.
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Affiliation(s)
- Scott T Akin
- Department of Chemistry, University of Georgia , Athens, Georgia 30602, United States
| | - Vicente Zamudio-Bayer
- Institut für Methoden und Instrumentierung der Forschung mit Synchrotronstrahlung, Helmholtz-Zentrum Berlin für Materialien und Energie, Albert-Einstein-Straße 15, 12489 Berlin, Germany
- Physikalisches Institut, Universität Freiburg , Stefan-Meier-Straße 21, 79104 Freiburg, Germany
| | - Kaining Duanmu
- Department of Chemistry, Chemical Theory Center, and the Supercomputing Institute, University of Minnesota , Minneapolis, Minnesota 55455, United States
| | - Georg Leistner
- Institut für Methoden und Instrumentierung der Forschung mit Synchrotronstrahlung, Helmholtz-Zentrum Berlin für Materialien und Energie, Albert-Einstein-Straße 15, 12489 Berlin, Germany
- Institut für Optik und Atomare Physik, Technische Universität Berlin , Hardenbergstraße 36, 10623 Berlin, Germany
| | - Konstantin Hirsch
- Institut für Methoden und Instrumentierung der Forschung mit Synchrotronstrahlung, Helmholtz-Zentrum Berlin für Materialien und Energie, Albert-Einstein-Straße 15, 12489 Berlin, Germany
- Institut für Optik und Atomare Physik, Technische Universität Berlin , Hardenbergstraße 36, 10623 Berlin, Germany
| | - Christine Bülow
- Institut für Methoden und Instrumentierung der Forschung mit Synchrotronstrahlung, Helmholtz-Zentrum Berlin für Materialien und Energie, Albert-Einstein-Straße 15, 12489 Berlin, Germany
- Institut für Optik und Atomare Physik, Technische Universität Berlin , Hardenbergstraße 36, 10623 Berlin, Germany
| | - Arkadiusz Ławicki
- Institut für Methoden und Instrumentierung der Forschung mit Synchrotronstrahlung, Helmholtz-Zentrum Berlin für Materialien und Energie, Albert-Einstein-Straße 15, 12489 Berlin, Germany
| | - Akira Terasaki
- East Tokyo Laboratory, Genesis Research Institute, Inc. , 717-86 Futamata, Ichikawa, Chiba 272-0001, Japan
- Department of Chemistry, Faculty of Science, Kyushu University , 744 Motooka, Nishi-ku, Fukuoka 819-0395, Japan
| | - Bernd von Issendorff
- Physikalisches Institut, Universität Freiburg , Stefan-Meier-Straße 21, 79104 Freiburg, Germany
| | - Donald G Truhlar
- Department of Chemistry, Chemical Theory Center, and the Supercomputing Institute, University of Minnesota , Minneapolis, Minnesota 55455, United States
| | - J Tobias Lau
- Institut für Methoden und Instrumentierung der Forschung mit Synchrotronstrahlung, Helmholtz-Zentrum Berlin für Materialien und Energie, Albert-Einstein-Straße 15, 12489 Berlin, Germany
| | - Michael A Duncan
- Department of Chemistry, University of Georgia , Athens, Georgia 30602, United States
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Niedner-schatteburg G. Cooperative Effects in Clusters and Oligonuclear Complexes of Transition Metals in Isolation. In: Dehnen S, editor. Clusters – Contemporary Insight in Structure and Bonding. Cham: Springer International Publishing; 2017. pp. 1-40. [DOI: 10.1007/430_2016_11] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register]
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