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Guo, Meiyuan
Publications (10 of 18) Show all publications
Guo, M., Källman, E., Pinjari, R. V., Couto, R. C., Sörensen, L. K., Lindh, R., . . . Lundberg, M. (2019). Fingerprinting Electronic Structure of Heme Iron by Ab Initio Modeling of Metal L-Edge X-ray Absorption Spectra. Journal of Chemical Theory and Computation, 15(1), 477-489
Open this publication in new window or tab >>Fingerprinting Electronic Structure of Heme Iron by Ab Initio Modeling of Metal L-Edge X-ray Absorption Spectra
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2019 (English)In: Journal of Chemical Theory and Computation, ISSN 1549-9618, E-ISSN 1549-9626, Vol. 15, no 1, p. 477-489Article in journal (Refereed) Published
Abstract [en]

The capability of the multiconfigurational restricted active space approach to identify electronic structure from spectral fingerprints is explored by applying it to iron L-edge X-ray absorption spectroscopy (XAS) of three heme systems that represent the limiting descriptions of iron in the Fe-O-2 bond, ferrous and ferric [Fe(P)(ImH)(2)](0/1+) (P = porphine, ImH = imidazole), and Fe-II(P). The level of agreement between experimental and simulated spectral shapes is calculated using the cosine similarity, which gives a quantitative and unbiased assignment. Further dimensions in fingerprinting are obtained from the L-edge branching ratio, the integrated absorption intensity, and the edge position. The results show how accurate ab initio simulations of metal L-edge XAS can complement calculations of relative energies to identify unknown species in chemical reactions.

National Category
Theoretical Chemistry
Identifiers
urn:nbn:se:uu:diva-375846 (URN)10.1021/acs.jctc.8b00658 (DOI)000455558200043 ()30513204 (PubMedID)
Funder
Swedish Research Council, 2012-3924Swedish Research Council, 2016-03398Knut and Alice Wallenberg Foundation, KAW-2013.0020Carl Tryggers foundation Swedish National Infrastructure for Computing (SNIC), snic2016-1-464
Available from: 2019-02-01 Created: 2019-02-01 Last updated: 2019-02-01Bibliographically approved
Blachucki, W., Kayser, Y., Czapla-Masztafiak, J., Guo, M., Juranic, P., Kavcic, M., . . . Szlachetko, J. (2019). Inception of electronic damage of matter by photon-driven post-ionization mechanisms. Structural Dynamics, 6(2), Article ID 024901.
Open this publication in new window or tab >>Inception of electronic damage of matter by photon-driven post-ionization mechanisms
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2019 (English)In: Structural Dynamics, ISSN 2329-7778, Vol. 6, no 2, article id 024901Article in journal (Refereed) Published
Abstract [en]

"Probe-before-destroy" methodology permitted diffraction and imaging measurements of intact specimens using ultrabright but highly destructive X-ray free-electron laser (XFEL) pulses. The methodology takes advantage of XFEL pulses ultrashort duration to outrun the destructive nature of the X-rays. Atomic movement, generally on the order of >50 fs, regulates the maximum pulse duration for intact specimen measurements. In this contribution, we report the electronic structure damage of a molecule with ultrashort X-ray pulses under preservation of the atoms' positions. A detailed investigation of the X-ray induced processes revealed that X-ray absorption events in the solvent produce a significant number of solvated electrons within attosecond and femtosecond timescales that are capable of coulombic interactions with the probed molecules. The presented findings show a strong influence on the experimental spectra coming from ionization of the probed atoms' surroundings leading to electronic structure modification much faster than direct absorption of photons. This work calls for consideration of this phenomenon in cases focused on samples embedded in, e.g., solutions or in matrices, which in fact concerns most of the experimental studies.

National Category
Atom and Molecular Physics and Optics Physical Chemistry
Identifiers
urn:nbn:se:uu:diva-383884 (URN)10.1063/1.5090332 (DOI)000466710000011 ()31041363 (PubMedID)
Funder
Knut and Alice Wallenberg Foundation, KAW-2013.0020
Available from: 2019-05-29 Created: 2019-05-29 Last updated: 2019-05-29Bibliographically approved
Esmieu, C., Guo, M., Redman, H. J., Lundberg, M. & Berggren, G. (2019). Synthesis of a miniaturized [FeFe] hydrogenase model system. Dalton Transactions, 48(7), 2280-2284
Open this publication in new window or tab >>Synthesis of a miniaturized [FeFe] hydrogenase model system
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2019 (English)In: Dalton Transactions, ISSN 1477-9226, E-ISSN 1477-9234, Vol. 48, no 7, p. 2280-2284Article in journal (Refereed) Published
Abstract [en]

The reaction occurring during artificial maturation of [FeFe] hydrogenase has been recreated using molecular systems. The formation of a miniaturized [FeFe] hydrogenase model system, generated through the combination of a [4Fe4S] cluster binding oligopeptide and an organometallic Fe complex, has been monitored by a range of spectroscopic techniques. A structure of the final assembly is suggested based on EPR and FTIR spectroscopy in combination with DFT calculations. The capacity of this novel H-cluster model to catalyze H-2 production in aqueous media at mild potentials is verified in chemical assays.

Place, publisher, year, edition, pages
ROYAL SOC CHEMISTRY, 2019
National Category
Inorganic Chemistry Theoretical Chemistry
Identifiers
urn:nbn:se:uu:diva-379261 (URN)10.1039/c8dt05085f (DOI)000459626400004 ()30667428 (PubMedID)
Funder
Swedish Research Council, 621-2014-5670Swedish Research Council Formas, 213-2014-880EU, European Research Council, 714102Wenner-Gren Foundations
Available from: 2019-03-15 Created: 2019-03-15 Last updated: 2019-03-15Bibliographically approved
Liu, T., Guo, M., Orthaber, A., Lomoth, R., Lundberg, M., Ott, S. & Hammarström, L. (2018). Accelerating proton-coupled electron transfer of metal hydrides in catalyst model reactions. Nature Chemistry, 10(8), 881-887
Open this publication in new window or tab >>Accelerating proton-coupled electron transfer of metal hydrides in catalyst model reactions
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2018 (English)In: Nature Chemistry, ISSN 1755-4330, E-ISSN 1755-4349, Vol. 10, no 8, p. 881-887Article in journal (Refereed) Published
Abstract [en]

Metal hydrides are key intermediates in catalytic proton reduction and dihydrogen oxidation. There is currently much interest in appending proton relays near the metal centre to accelerate catalysis by proton-coupled electron transfer (PCET). However, the elementary PCET steps and the role of the proton relays are still poorly understood, and direct kinetic studies of these processes are scarce. Here, we report a series of tungsten hydride complexes as proxy catalysts, with covalently attached pyridyl groups as proton acceptors. The rate of their PCET reaction with external oxidants is increased by several orders of magnitude compared to that of the analogous systems with external pyridine on account of facilitated proton transfer. Moreover, the mechanism of the PCET reaction is altered by the appended bases. A unique feature is that the reaction can be tuned to follow three distinct PCET mechanisms-electron-first, proton-first or a concerted reaction-with very different sensitivities to oxidant and base strength. Such knowledge is crucial for rational improvements of solar fuel catalysts.

National Category
Physical Chemistry
Identifiers
urn:nbn:se:uu:diva-357209 (URN)10.1038/s41557-018-0076-x (DOI)000439420400015 ()30013192 (PubMedID)
Funder
Swedish Research Council, 2016-04271Knut and Alice Wallenberg Foundation, 2011.0067
Available from: 2018-08-13 Created: 2018-08-13 Last updated: 2019-01-04Bibliographically approved
Kubin, M., Guo, M., Ekimova, M., Källman, E., Kern, J., Yachandra, V. K., . . . Wernet, P. (2018). Cr L-Edge X-ray Absorption Spectroscopy of CrIII(acac)3 in Solution with Measured and Calculated Absolute Absorption Cross Sections. Journal of Physical Chemistry B, 122(29), 7375-7384
Open this publication in new window or tab >>Cr L-Edge X-ray Absorption Spectroscopy of CrIII(acac)3 in Solution with Measured and Calculated Absolute Absorption Cross Sections
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2018 (English)In: Journal of Physical Chemistry B, ISSN 1520-6106, E-ISSN 1520-5207, Vol. 122, no 29, p. 7375-7384Article in journal (Refereed) Published
Abstract [en]

X-ray absorption spectroscopy at the L-edge of 3d transition metals is widely used for probing the valence electronic structure at the metal site via 2p–3d transitions. Assessing the information contained in L-edge absorption spectra requires systematic comparison of experiment and theory. We here investigate the Cr L-edge absorption spectrum of high-spin chromium acetylacetonate CrIII(acac)3 in solution. Using a transmission flatjet enables determining absolute absorption cross sections and spectra free from X-ray-induced sample damage. We address the challenges of measuring Cr L absorption edges spectrally close to the O K absorption edge of the solvent. We critically assess how experimental absorption cross sections can be used to extract information on the electronic structure of the studied system by comparing our results of this CrIII (3d3) complex to our previous work on L-edge absorption cross sections of MnIII(acac)3 (3d4) and MnII(acac)2 (3d5). Considering our experimental uncertainties, the most insightful experimental observable for this d3(CrIII)–d4(MnIII)–d5(MnII) series is the L-edge branching ratio, and we discuss it in comparison to semiempirical multiplet theory and ab initio restricted active space calculations. We further discuss and analyze trends in integrated absorption cross sections and correlate the spectral shapes with the local electronic structure at the metal sites.

National Category
Physical Chemistry
Identifiers
urn:nbn:se:uu:diva-357211 (URN)10.1021/acs.jpcb.8b04190 (DOI)000440519900017 ()29957942 (PubMedID)
Funder
NIH (National Institute of Health), GM110501; GM126289 ;GM55302German Research Foundation (DFG), DEG-NI 492/11-1Knut and Alice Wallenberg Foundation, KAW-2013.0020Swedish Research CouncilSwedish National Infrastructure for Computing (SNIC), snic2016-1-464National Supercomputer Centre (NSC), Sweden, snic2016-1-508
Available from: 2018-08-13 Created: 2018-08-13 Last updated: 2018-11-05Bibliographically approved
Kubin, M., Guo, M., Ekimova, M., Baker, M. L., Kroll, T., Källman, E., . . . Wernet, P. (2018). Direct Determination of Absolute Absorption Cross Sections at the L-Edge of Dilute Mn Complexes in Solution Using a Transmission Flatjet. Inorganic Chemistry, 57(9), 5449-5462
Open this publication in new window or tab >>Direct Determination of Absolute Absorption Cross Sections at the L-Edge of Dilute Mn Complexes in Solution Using a Transmission Flatjet
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2018 (English)In: Inorganic Chemistry, ISSN 0020-1669, E-ISSN 1520-510X, Vol. 57, no 9, p. 5449-5462Article in journal (Refereed) Published
Abstract [en]

The 3d transition metals play a pivotal role in many charge transfer processes in catalysis and biology. X-ray absorption spectroscopy at the L-edge of metal sites probes metal 2p–3d excitations, providing key access to their valence electronic structure, which is crucial for understanding these processes. We report L-edge absorption spectra of MnII(acac)2 and MnIII(acac)3 complexes in solution, utilizing a liquid flatjet for X-ray absorption spectroscopy in transmission mode. With this, we derive absolute absorption cross-sections for the L-edge transitions with peak magnitudes as large as 12 and 9 Mb for MnII(acac)2 and MnIII(acac)3, respectively. We provide insight into the electronic structure with ab initio restricted active space calculations of these L-edge transitions, reproducing the experimental spectra with excellent agreement in terms of shapes, relative energies, and relative intensities for the two complexes. Crystal field multiplet theory is used to assign spectral features in terms of the electronic structure. Comparison to charge transfer multiplet calculations reveals the importance of charge transfer in the core-excited final states. On the basis of our experimental observations, we extrapolate the feasibility of 3d transition metal L-edge absorption spectroscopy using the liquid flatjet approach in probing highly dilute biological solution samples and possible extensions to table-top soft X-ray sources.

Place, publisher, year, edition, pages
AMER CHEMICAL SOC, 2018
National Category
Physical Chemistry
Identifiers
urn:nbn:se:uu:diva-356498 (URN)10.1021/acs.inorgchem.8b00419 (DOI)000431833500077 ()29634280 (PubMedID)
Funder
Swedish Research CouncilKnut and Alice Wallenberg Foundation, KAW-2013.0020NIH (National Institute of Health), GM110501; GM126289; GM55302German Research Foundation (DFG), DFG-NI 492/11-1Swedish National Infrastructure for Computing (SNIC), snic2016-1-464
Available from: 2018-07-30 Created: 2018-07-30 Last updated: 2019-01-04Bibliographically approved
Norell, J., Jay, R. M., Hantschmann, M., Eckert, S., Guo, M., Gaffney, K. J., . . . Odelius, M. (2018). Fingerprints of electronic, spin and structural dynamics from resonant inelastic soft X-ray scattering in transient photo-chemical species. Physical Chemistry, Chemical Physics - PCCP, 20(10), 7243-7253
Open this publication in new window or tab >>Fingerprints of electronic, spin and structural dynamics from resonant inelastic soft X-ray scattering in transient photo-chemical species
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2018 (English)In: Physical Chemistry, Chemical Physics - PCCP, ISSN 1463-9076, E-ISSN 1463-9084, Vol. 20, no 10, p. 7243-7253Article in journal (Refereed) Published
Abstract [en]

We describe how inversion symmetry separation of electronic state manifolds in resonant inelastic soft X-ray scattering (RIXS) can be applied to probe excited-state dynamics with compelling selectivity. In a case study of Fe L-3-edge RIXS in the ferricyanide complex Fe(CN)(6)(3-), we demonstrate with multi-configurational restricted active space spectrum simulations how the information content of RIXS spectral fingerprints can be used to unambiguously separate species of different electronic configurations, spin multiplicities, and structures, with possible involvement in the decay dynamics of photo-excited ligand-to-metal charge-transfer. Specifically, we propose that this could be applied to confirm or reject the presence of a hitherto elusive transient Quartet species. Thus, RIXS offers a particular possibility to settle a recent controversy regarding the decay pathway, and we expect the technique to be similarly applicable in other model systems of photo-induced dynamics.

Place, publisher, year, edition, pages
Royal Society of Chemistry, 2018
National Category
Physical Chemistry
Identifiers
urn:nbn:se:uu:diva-352727 (URN)10.1039/c7cp08326b (DOI)000429286100052 ()29484313 (PubMedID)
Funder
Swedish Research Council, 2015-03956EU, European Research Council, 669531 EDAXSwedish Research CouncilKnut and Alice Wallenberg Foundation, KAW-2013.0020
Available from: 2018-06-07 Created: 2018-06-07 Last updated: 2018-06-07Bibliographically approved
Norell, J., Jay, R., Hantschmann, M., Eckert, S., Guo, M., Gaffney, K., . . . Odelius, M. (2018). Fingerprints of electronic, spin and structural dynamics from resonant inelastic soft x-ray scattering in transient photo-chemical species. Paper presented at 256th National Meeting and Exposition of the American-Chemical-Society (ACS) - Nanoscience, Nanotechnology and Beyond, AUG 19-23, 2018, Boston, MA. Abstract of Papers of the American Chemical Society, 256
Open this publication in new window or tab >>Fingerprints of electronic, spin and structural dynamics from resonant inelastic soft x-ray scattering in transient photo-chemical species
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2018 (English)In: Abstract of Papers of the American Chemical Society, ISSN 0065-7727, Vol. 256Article in journal, Meeting abstract (Other academic) Published
Place, publisher, year, edition, pages
AMER CHEMICAL SOC, 2018
National Category
Physical Chemistry
Identifiers
urn:nbn:se:uu:diva-370053 (URN)000447609103557 ()
Conference
256th National Meeting and Exposition of the American-Chemical-Society (ACS) - Nanoscience, Nanotechnology and Beyond, AUG 19-23, 2018, Boston, MA
Available from: 2018-12-20 Created: 2018-12-20 Last updated: 2018-12-20Bibliographically approved
Kubin, M., Guo, M., Kroll, T., Lächel, H., Källman, E., Baker, M. L., . . . Wernet, P. (2018). Probing the oxidation state of transition metal complexes: a case study on how charge and spin densities determine Mn L-edge X-ray absorption energies. Chem. Sci., 9(33), 6813-6829
Open this publication in new window or tab >>Probing the oxidation state of transition metal complexes: a case study on how charge and spin densities determine Mn L-edge X-ray absorption energies
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2018 (English)In: Chem. Sci., Vol. 9, no 33, p. 6813-6829Article in journal (Refereed) Published
Abstract [en]

Transition metals in inorganic systems and metalloproteins can occur in different oxidation states, which makes them ideal redox-active catalysts. To gain a mechanistic understanding of the catalytic reactions, knowledge of the oxidation state of the active metals, ideally in operando, is therefore critical. L-edge X-ray absorption spectroscopy (XAS) is a powerful technique that is frequently used to infer the oxidation state via a distinct blue shift of L-edge absorption energies with increasing oxidation state. A unified description accounting for quantum-chemical notions whereupon oxidation does not occur locally on the metal but on the whole molecule and the basic understanding that L-edge XAS probes the electronic structure locally at the metal has been missing to date. Here we quantify how charge and spin densities change at the metal and throughout the molecule for both redox and core-excitation processes. We explain the origin of the L-edge XAS shift between the high-spin complexes MnII(acac)2 and MnIII(acac)3 as representative model systems and use ab initio theory to uncouple effects of oxidation-state changes from geometric effects. The shift reflects an increased electron affinity of MnIII in the core-excited states compared to the ground state due to a contraction of the Mn 3d shell upon core-excitation with accompanied changes in the classical Coulomb interactions. This new picture quantifies how the metal-centered core hole probes changes in formal oxidation state and encloses and substantiates earlier explanations. The approach is broadly applicable to mechanistic studies of redox-catalytic reactions in molecular systems where charge and spin localization/delocalization determine reaction pathways.

Place, publisher, year, edition, pages
The Royal Society of Chemistry, 2018
National Category
Inorganic Chemistry
Identifiers
urn:nbn:se:uu:diva-357210 (URN)10.1039/C8SC00550H (DOI)000443270300009 ()30310614 (PubMedID)
Funder
Swedish Research CouncilKnut and Alice Wallenberg Foundation, KAW-2013.0020
Available from: 2018-08-13 Created: 2018-08-13 Last updated: 2018-11-16Bibliographically approved
Kubin, M., Kern, J., Guo, M., Källman, E., Mitzner, R., Yachandra, V. K., . . . Wernet, P. (2018). X-ray-induced sample damage at the Mn L-edge: a case study for soft X-ray spectroscopy of transition metal complexes in solution. Physical Chemistry, Chemical Physics - PCCP, 20(24), 16817-16827
Open this publication in new window or tab >>X-ray-induced sample damage at the Mn L-edge: a case study for soft X-ray spectroscopy of transition metal complexes in solution
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2018 (English)In: Physical Chemistry, Chemical Physics - PCCP, ISSN 1463-9076, E-ISSN 1463-9084, Vol. 20, no 24, p. 16817-16827Article in journal (Refereed) Published
Abstract [en]

X-ray induced sample damage can impede electronic and structural investigations of radiation-sensitive samples studied with X-rays. Here we quantify dose-dependent sample damage to the prototypical Mn-III(acac)(3) complex in solution and at room temperature for the soft X-ray range, using X-ray absorption spectroscopy at the Mn L-edge. We observe the appearance of a reduced Mn-II species as the X-ray dose is increased. We find a half-damage dose of 1.6 MGy and quantify a spectroscopically tolerable dose on the order of 0.3 MGy (1 Gy = 1 J kg(-1)), where 90% of Mn-III(acac)(3) are intact. Our dose-limit is around one order of magnitude lower than the Henderson limit (half-damage dose of 20 MGy) which is commonly employed for protein crystallography with hard X-rays. It is comparable, however, to the dose-limits obtained for collecting un-damaged Mn K-edge spectra of the photosystem II protein, using hard X-rays. The dose-dependent reduction of Mn-III observed here for solution samples occurs at a dose limit that is two to four orders of magnitude smaller than the dose limits previously reported for soft X-ray spectroscopy of iron samples in the solid phase. We compare our measured to calculated spectra from ab initio restricted active space (RAS) theory and discuss possible mechanisms for the observed dose-dependent damage of Mn-III(acac)(3) in solution. On the basis of our results, we assess the influence of sample damage in other experimental studies with soft X-rays from storage-ring synchrotron radiation sources and X-ray free-electron lasers.

Place, publisher, year, edition, pages
RSC Publishing, 2018
National Category
Physical Chemistry
Identifiers
urn:nbn:se:uu:diva-357207 (URN)10.1039/c8cp03094d (DOI)000436032900053 ()
Funder
Swedish Research Council, 2012-3924Knut and Alice Wallenberg Foundation, KAW-2013.0020Swedish National Infrastructure for Computing (SNIC), snic2016-1-464NIH (National Institute of Health), GM110501NIH (National Institute of Health), GM126289NIH (National Institute of Health), GM55302
Available from: 2018-08-13 Created: 2018-08-13 Last updated: 2018-09-14Bibliographically approved
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