TY  - JOUR
A1  - Kunnus, Kristjan
A1  - Zhang, Wenkai
A1  - Delcey, Mickael G.
A1  - Pinjari, Rahul V.
A1  - Miedema, Piter S.
A1  - Schreck, Simon
A1  - Quevedo, Wilson
A1  - Schröder, Henning
A1  - Föhlisch, Alexander
A1  - Gaffney, Kelly J.
A1  - Lundberg, Marcus
A1  - Odelius, Michael
A1  - Wernet, Philippe
T1  - Viewing the Valence Electronic Structure of Ferric and Ferrous Hexacyanide in Solution from the Fe and Cyanide Perspectives
JF  - The journal of physical chemistry : B, Condensed matter, materials, surfaces, interfaces & biophysical chemistry
N2  - The valence-excited states of ferric and ferrous hexacyanide ions in aqueous solution were mapped by resonant inelastic X-ray scattering (RIXS) at the Fe L-2,L-3 and N K edges. Probing of both the central Fe and the ligand N atoms enabled identification of the metal-and ligand-centered excited states, as well as ligand-to-metal and metal-to-ligand charge-transfer excited states. Ab initio calculations utilizing the RASPT2 method were used to simulate the Fe L-2,L-3-edge RIXS spectra and enabled quantification of the covalencies of both occupied and empty orbitals of pi and sigma symmetry. We found that pi back-donation in the ferric complex is smaller than that in the ferrous complex. This is evidenced by the relative amounts of Fe 3d character in the nominally 2 pi CN- molecular orbital of 7% and 9% in ferric and ferrous hexacyanide, respectively. Utilizing the direct sensitivity of Fe L-3-edge RIXS to the Fe 3d character in the occupied molecular orbitals, we also found that the donation interactions are dominated by sigma bonding. The latter was found to be stronger in the ferric complex, with an Fe 3d contribution to the nominally 5 sigma CN- molecular orbitals of 29% compared to 20% in the ferrous complex. These results are consistent with the notion that a higher charge at the central metal atom increases donation and decreases back-donation.
Y1  - 2016
U6  - https://doi.org/10.1021/acs.jpcb.6b04751
SN  - 1520-6106
VL  - 120
SP  - 7182
EP  - 7194
PB  - American Chemical Society
CY  - Washington
ER  - 
TY  - JOUR
A1  - Leitner, T.
A1  - Josefsson, Ida
A1  - Mazza, T.
A1  - Miedema, Piter S.
A1  - Schröder, H.
A1  - Beye, Martin
A1  - Kunnus, Kristjan
A1  - Schreck, S.
A1  - Düsterer, Stefan
A1  - Föhlisch, Alexander
A1  - Meyer, M.
A1  - Odelius, Michael
A1  - Wernet, Philippe
T1  - Time-resolved electron spectroscopy for chemical analysis of photodissociation
BT  - Photoelectron spectra of Fe(CO)(5), Fe(CO)(4), and Fe(CO)(3)
JF  - The journal of chemical physics : bridges a gap between journals of physics and journals of chemistr
N2  - The prototypical photoinduced dissociation of Fe(CO)(5) in the gas phase is used to test time-resolved x-ray photoelectron spectroscopy for studying photochemical reactions. Upon one-photon excitation at 266 nm, Fe(CO)(5) successively dissociates to Fe(CO)(4) and Fe(CO)(3) along a pathway where both fragments retain the singlet multiplicity of Fe(CO)(5). The x-ray free-electron laser FLASH is used to probe the reaction intermediates Fe(CO)(4) and Fe(CO)(3) with time-resolved valence and core-level photoelectron spectroscopy, and experimental results are interpreted with ab initio quantum chemical calculations. Changes in the valence photoelectron spectra are shown to reflect changes in the valenceorbital interactions upon Fe-CO dissociation, thereby validating fundamental theoretical concepts in Fe-CO bonding. Chemical shifts of CO 3 sigma inner-valence and Fe 3 sigma core-level binding energies are shown to correlate with changes in the coordination number of the Fe center. We interpret this with coordination-dependent charge localization and core-hole screening based on calculated changes in electron densities upon core-hole creation in the final ionic states. This extends the established capabilities of steady-state electron spectroscopy for chemical analysis to time-resolved investigations. It could also serve as a benchmark for howcharge and spin density changes in molecular dissociation and excited-state dynamics are expressed in valence and core-level photoelectron spectroscopy. Published by AIP Publishing.
Y1  - 2018
U6  - https://doi.org/10.1063/1.5035149
SN  - 0021-9606
SN  - 1089-7690
VL  - 149
IS  - 4
PB  - American Institute of Physics
CY  - Melville
ER  - 
TY  - JOUR
A1  - Jay, Raphael Martin
A1  - Eckert, Sebastian
A1  - Fondell, Mattis
A1  - Miedema, Piter S.
A1  - Norell, Jesper
A1  - Pietzsch, Annette
A1  - Quevedo, Wilson
A1  - Niskanen, Johannes
A1  - Kunnus, Kristjan
A1  - Föhlisch, Alexander
T1  - The nature of frontier orbitals under systematic ligand exchange in (pseudo-)octahedral Fe(II) complexes
JF  - Physical chemistry, chemical physics : a journal of European Chemical Societies
N2  - Understanding and controlling properties of transition metal complexes is a crucial step towards tailoring materials for sustainable energy applications. In a systematic approach, we use resonant inelastic X-ray scattering to study the influence of ligand substitution on the valence electronic structure around an aqueous iron(II) center. Exchanging cyanide with 2-2′-bipyridine ligands reshapes frontier orbitals in a way that reduces metal 3d charge delocalization onto the ligands. This net decrease of metal–ligand covalency results in lower metal-centered excited state energies in agreement with previously reported excited state dynamics. Furthermore, traces of solvent-effects were found indicating a varying interaction strength of the solvent with ligands of different character. Our results demonstrate how ligand exchange can be exploited to shape frontier orbitals of transition metal complexes in solution-phase chemistry; insights upon which future efforts can built when tailoring the functionality of photoactive systems for light-harvesting applications.
Y1  - 2018
U6  - https://doi.org/10.1039/c8cp04341h
SN  - 1463-9076
SN  - 1463-9084
VL  - 20
IS  - 44
SP  - 27745
EP  - 27751
PB  - Royal Society of Chemistry
CY  - Cambridge
ER  - 
TY  - JOUR
A1  - Kunnus, Kristjan
A1  - Josefsson, I.
A1  - Schreck, Simon Frederik
A1  - Quevedo, W.
A1  - Miedema, P. S.
A1  - Techert, S.
A1  - de Groot, F. M. F.
A1  - Föhlisch, Alexander
A1  - Odelius, M.
A1  - Wernet, Ph.
T1  - Quantifying covalent interactions with resonant inelastic soft X-ray scattering
BT  - case study of Ni2+ aqua complex
JF  - Chemical physics letters
N2  - We analyze the effects of covalent interactions in Ni 2p3d resonant inelastic X-ray scattering (RIXS) spectra from aqueous Ni2+ ions and find that the relative RIXS intensities of ligand-to-metal charge-transfer final states with respect to the ligand-field final states reflect the covalent mixing between Ni 3d and water orbitals. Specifically, the experimental intensity ratio at the Ni L-3-edge allows to determine that the Ni 3d orbitals have on average 5.5% of water character. We propose that 2p3d RIXS at the Ni L-3-edge can be utilized to quantify covalency in Ni complexes without the use of external references or simulations.
KW  - Transition-metal ion
KW  - Aqueous solution
KW  - Covalent interaction
KW  - Resonant inelastic X-ray scattering
KW  - Ligand-field state
KW  - Charge-transfer state
Y1  - 2016
U6  - https://doi.org/10.1016/j.cplett.2016.12.046
SN  - 0009-2614
SN  - 1873-4448
VL  - 669
SP  - 196
EP  - 201
PB  - Elsevier
CY  - Amsterdam
ER  - 
TY  - JOUR
A1  - Wernet, Philippe
A1  - Kunnus, Kristjan
A1  - Josefsson, Ida
A1  - Rajkovic, Ivan
A1  - Quevedo, Wilson
A1  - Beye, Martin
A1  - Schreck, Simon
A1  - Gruebel, S.
A1  - Scholz, Mirko
A1  - Nordlund, Dennis
A1  - Zhang, Wenkai
A1  - Hartsock, Robert W.
A1  - Schlotter, William F.
A1  - Turner, Joshua J.
A1  - Kennedy, Brian
A1  - Hennies, Franz
A1  - de Groot, Frank M. F.
A1  - Gaffney, Kelly J.
A1  - Techert, Simone
A1  - Odelius, Michael
A1  - Föhlisch, Alexander
T1  - Orbital-specific mapping of the ligand exchange dynamics of Fe(CO)(5) in solution
JF  - Nature : the international weekly journal of science
N2  - Transition-metal complexes have long attracted interest for fundamental chemical reactivity studies and possible use in solar energy conversion(1,2). Electronic excitation, ligand loss from the metal centre, or a combination of both, creates changes in charge and spin density at the metal site(3-11) that need to be controlled to optimize complexes for photocatalytic hydrogen production(8) and selective carbon-hydrogen bond activation(9-11). An understanding at the molecular level of how transition-metal complexes catalyse reactions, and in particular of the role of the short-lived and reactive intermediate states involved, will be critical for such optimization. However, suitable methods for detailed characterization of electronic excited states have been lacking. Here we show, with the use of X-ray laser-based femtosecond-resolution spectroscopy and advanced quantum chemical theory to probe the reaction dynamics of the benchmark transition-metal complex Fe(CO)(5) in solution, that the photo-induced removal of CO generates the 16-electron Fe(CO)(4) species, a homogeneous catalyst(12,13) with an electron deficiency at the Fe centre(14,15), in a hitherto unreported excited singlet state that either converts to the triplet ground state or combines with a CO or solvent molecule to regenerate a penta-coordinated Fe species on a sub-picosecond timescale. This finding, which resolves the debate about the relative importance of different spin channels in the photochemistry of Fe(CO)(5) (refs 4, 16-20), was made possible by the ability of femtosecond X-ray spectroscopy to probe frontier-orbital interactions with atom specificity. We expect the method to be broadly applicable in the chemical sciences, and to complement approaches that probe structural dynamics in ultrafast processes.
Y1  - 2015
U6  - https://doi.org/10.1038/nature14296
SN  - 0028-0836
SN  - 1476-4687
VL  - 520
IS  - 7545
SP  - 78
EP  - 81
PB  - Nature Publ. Group
CY  - London
ER  - 
TY  - JOUR
A1  - Mitzner, Rolf
A1  - Rehanek, Jens
A1  - Kern, Jan
A1  - Gul, Sheraz
A1  - Hattne, Johan
A1  - Taguchi, Taketo
A1  - Alonso-Mori, Roberto
A1  - Tran, Rosalie
A1  - Weniger, Christian
A1  - Schröder, Henning
A1  - Quevedo, Wilson
A1  - Laksmono, Hartawan
A1  - Sierra, Raymond G.
A1  - Han, Guangye
A1  - Lassalle-Kaiser, Benedikt
A1  - Koroidov, Sergey
A1  - Kubicek, Katharina
A1  - Schreck, Simon
A1  - Kunnus, Kristjan
A1  - Brzhezinskaya, Maria
A1  - Firsov, Alexander
A1  - Minitti, Michael P.
A1  - Turner, Joshua J.
A1  - Möller, Stefan
A1  - Sauter, Nicholas K.
A1  - Bogan, Michael J.
A1  - Nordlund, Dennis
A1  - Schlotter, William F.
A1  - Messinger, Johannes
A1  - Borovik, Andrew S.
A1  - Techert, Simone
A1  - de Groot, Frank M. F.
A1  - Föhlisch, Alexander
A1  - Erko, Alexei
A1  - Bergmann, Uwe
A1  - Yachandra, Vittal K.
A1  - Wernet, Philippe
A1  - Yano, Junko
T1  - L-edge x-ray absorption spectroscopy of dilute systems relevant to metalloproteins using an X-ray free-electron laser
JF  - The journal of physical chemistry letters
N2  - L-edge spectroscopy of 3d transition metals provides important electronic structure information and has been used in many fields. However, the use of this method for studying dilute aqueous systems, such as metalloenzymes, has not been prevalent because of severe radiation damage and the lack of suitable detection systems. Here we present spectra from a dilute Mn aqueous solution using a high-transmission zone-plate spectrometer at the Linac Coherent Light Source (LCLS). The spectrometer has been optimized for discriminating the Mn L-edge signal from the overwhelming 0 K-edge background that arises from water and protein itself, and the ultrashort LCLS X-ray pulses can outrun X-ray induced damage. We show that the deviations of the partial-fluorescence yield-detected spectra from the true absorption can be well modeled using the state-dependence of the fluorescence yield, and discuss implications for the application of our concept to biological samples.
Y1  - 2013
U6  - https://doi.org/10.1021/jz401837f
SN  - 1948-7185
VL  - 4
IS  - 21
SP  - 3641
EP  - 3647
PB  - American Chemical Society
CY  - Washington
ER  - 
TY  - JOUR
A1  - Kunnus, Kristjan
A1  - Josefsson, I.
A1  - Rajkovic, Ivan
A1  - Schreck, Simon
A1  - Quevedo, Wilson
A1  - Beye, Martin
A1  - Weniger, C.
A1  - Gruebel, S.
A1  - Scholz, M.
A1  - Nordlund, D.
A1  - Zhang, W.
A1  - Hartsock, R. W.
A1  - Gaffney, K. J.
A1  - Schlotter, W. F.
A1  - Turner, J. J.
A1  - Kennedy, B.
A1  - Hennies, F.
A1  - de Groot, F. M. F.
A1  - Techert, S.
A1  - Odelius, Michael
A1  - Wernet, Ph.
A1  - Föhlisch, Alexander
T1  - Identification of the dominant photochemical pathways and mechanistic insights to the ultrafast ligand exchange of Fe(CO)(5) to Fe(CO)(4)EtOH
JF  - Structural dynamics
N2  - We utilized femtosecond time-resolved resonant inelastic X-ray scattering and ab initio theory to study the transient electronic structure and the photoinduced molecular dynamics of a model metal carbonyl photocatalyst Fe(CO)(5) in ethanol solution. We propose mechanistic explanation for the parallel ultrafast intra-molecular spin crossover and ligation of the Fe(CO)(4) which are observed following a charge transfer photoexcitation of Fe(CO)(5) as reported in our previous study [ Wernet et al., Nature 520, 78 (2015)]. We find that branching of the reaction pathway likely happens in the (1)A(1) state of Fe(CO)(4). A sub-picosecond time constant of the spin crossover from B-1(2) to B-3(2) is rationalized by the proposed B-1(2) -> (1)A(1) -> B-3(2) mechanism. Ultrafast ligation of the B-1(2) Fe(CO)(4) state is significantly faster than the spin-forbidden and diffusion limited ligation process occurring from the B-3(2) Fe(CO)(4) ground state that has been observed in the previous studies. We propose that the ultrafast ligation occurs via B-1(2) -> (1)A(1) -> (1)A'Fe(CO)(4)EtOH pathway and the time scale of the (1)A(1) Fe(CO)(4) state ligation is governed by the solute-solvent collision frequency. Our study emphasizes the importance of understanding the interaction of molecular excited states with the surrounding environment to explain the relaxation pathways of photoexcited metal carbonyls in solution. (C) 2016 Author(s).
Y1  - 2016
U6  - https://doi.org/10.1063/1.4941602
SN  - 2329-7778
VL  - 3
PB  - American Institute of Physics
CY  - Washington
ER  - 
TY  - JOUR
A1  - Kunnus, Kristjan
A1  - Josefsson, Ida
A1  - Schreck, Simon
A1  - Quevedo, Wilson
A1  - Miedema, Piter S.
A1  - Techert, Simone
A1  - de Groot, Frank M. F.
A1  - Odelius, Michael
A1  - Wernet, Philippe
A1  - Föhlisch, Alexander
T1  - From Ligand Fields to Molecular Orbitals: Probing the Local Valence Electronic Structure of Ni2+ in Aqueous Solution with Resonant Inelastic X-ray Scattering
JF  - The journal of physical chemistry : B, Condensed matter, materials, surfaces, interfaces & biophysical chemistry
N2  - Bonding of the Ni2+(aq) complex is investigated with an unprecedented combination of resonant inelastic X-ray scattering (RIXS) measurements and ab initio calculations at the Ni L absorption edge. The spectra directly reflect the relative energies of the ligand-field and charge-transfer valence-excited states. They give element-specific access with atomic resolution to the ground-state electronic structure of the complex and allow quantification of ligand-field strength and 3d-3d electron correlation interactions in the Ni2+(aq) complex. The experimentally determined ligand-field strength is 10Dq = 1.1 eV. This and the Racah parameters characterizing 3d-3d Coulomb interactions B = 0.13 eV and C = 0.42 eV as readily derived from the measured energies match very well with the results from UV-vis spectroscopy. Our results demonstrate how L-edge RIXS can be used to complement existing spectroscopic tools for the investigation of bonding in 3d transition-metal coordination compounds in solution. The ab initio RASPT2 calculation is successfully used to simulate the L-edge RIXS spectra.
Y1  - 2013
U6  - https://doi.org/10.1021/jp4100813
SN  - 1520-6106
VL  - 117
IS  - 51
SP  - 16512
EP  - 16521
PB  - American Chemical Society
CY  - Washington
ER  - 
TY  - JOUR
A1  - Kunnus, Kristjan
A1  - Schreck, Simon
A1  - Föhlisch, Alexander
T1  - Free-electron laser based resonant inelastic X-ray scattering on molecules and liquids
JF  - Journal of electron spectroscopy and related phenomena : the international journal on theoretical and experimental aspects of electron spectroscopy
N2  - The unprecedented beam properties of free-electron laser based X-ray sources enable novel resonant inelastic X-ray scattering (RIXS) experiments. Femtosecond time-resolved RIXS can be used to follow charge, spin and structural dynamics of dilute solute molecules in solution. Ultrashort X-ray pulses allow probing of highly radiation sensitive states of matter such as the metastable phase of supercooled liquid water. Nonlinear X-ray probes like amplified spontaneous emission and stimulated resonant X-ray scattering provide an enhanced selectivity and sensitivity as well as a path to control radiation damage and increase the photon yields in RIXS experiments. (C) 2015 Elsevier B.V. All rights reserved.
KW  - Free-electron laser
KW  - RIXS
KW  - Pump-probe
KW  - Nonlinear X-ray spectroscopy
KW  - Molecules
KW  - Liquids
Y1  - 2015
U6  - https://doi.org/10.1016/j.elspec.2015.08.012
SN  - 0368-2048
SN  - 1873-2526
VL  - 204
SP  - 345
EP  - 355
PB  - Elsevier
CY  - Amsterdam
ER  - 
TY  - JOUR
A1  - Schreck, Simon
A1  - Pietzsch, Annette
A1  - Kunnus, Kristjan
A1  - Kennedy, Brian
A1  - Quevedo, Wilson
A1  - Miedema, Piter S.
A1  - Wernet, Philippe
A1  - Föhlisch, Alexander
T1  - Dynamics of the OH group and the electronic structure of liquid alcohols
JF  - Structural dynamics
N2  - In resonant inelastic soft x-ray scattering (RIXS) from molecular and liquid systems, the interplay of ground state structural and core-excited state dynamical contributions leads to complex spectral shapes that partially allow for ambiguous interpretations. In this work, we dissect these contributions in oxygen K-edge RIXS from liquid alcohols. We use the scattering into the electronic ground state as an accurate measure of nuclear dynamics in the intermediate core-excited state of the RIXS process. We determine the characteristic time in the core-excited state until nuclear dynamics give a measurable contribution to the RIXS spectral profiles to tau(dyn) = 1.2 +/- 0.8 fs. By detuning the excitation energy below the absorption resonance we reduce the effective scattering time below sdyn, and hence suppress these dynamical contributions to a minimum. From the corresponding RIXS spectra of liquid methanol, we retrieve the "dynamic-free" density of states and find that it is described solely by the electronic states of the free methanol molecule. From this and from the comparison of normal and deuterated methanol, we conclude that the split peak structure found in the lone-pair emission region at non-resonant excitation originates from dynamics in the O-H bond in the core-excited state. We find no evidence that this split peak feature is a signature of distinct ground state structural complexes in liquid methanol. However, we demonstrate how changes in the hydrogen bond coordination within the series of linear alcohols from methanol to hexanol affect the split peak structure in the liquid alcohols. (C) 2014 Author(s). All article content, except where otherwise noted, is licensed under a Creative Commons Attribution 3.0 Unported License.
Y1  - 2014
U6  - https://doi.org/10.1063/1.4897981
SN  - 2329-7778
VL  - 1
IS  - 5
PB  - American Institute of Physics
CY  - Melville
ER  - 
TY  - GEN
A1  - Jay, Raphael J.
A1  - Norell, Jesper
A1  - Kunnus, Kristjan
A1  - Lundberg, Marcus
A1  - Gaffney, Kelly
A1  - Wernet, Philippe
A1  - Odelius, Michael
A1  - Föhlisch, Alexander
T1  - Dynamcis of local charge densities and metal-ligand covalency in iron complexes from femtosecond resonant inelastic soft X-ray scattering
T2  - Abstracts of Papers of the American Chemical Society
Y1  - 2018
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:se:uu:diva-370051
SN  - 0065-7727
VL  - 256
PB  - American Chemical Society
CY  - Washington
ER  - 
TY  - JOUR
A1  - Wernet, Philippe
A1  - Kunnus, Kristjan
A1  - Schreck, Simon
A1  - Quevedo, Wilson
A1  - Kurian, Reshmi
A1  - Techert, Simone
A1  - de Groot, Frank M. F.
A1  - Odelius, Michael
A1  - Föhlisch, Alexander
T1  - Dissecting local atomic and intermolecular interactions of transition-metal ions in solution with selective X-ray spectroscopy
JF  - The journal of physical chemistry letters
N2  - Determining covalent and charge-transfer contributions to bonding in solution has remained an experimental challenge. Here, the quenching of fluorescence decay channels as expressed in dips in the L-edge X-ray spectra of solvated 3d transition-metal ions and complexes was reported as a probe. With a full set of experimental and theoretical ab initio L-edge X-ray spectra of aqueous Cr3+, including resonant inelastic X-ray scattering, we address covalency and charge transfer for this prototypical transition-metal ion in solution. We dissect local atomic effects from intermolecular interactions and quantify X-ray optical effects. We find no evidence for the asserted ultrafast charge transfer to the solvent and show that the dips are readily explained by X-ray optical effects and local atomic state dependence of the fluorescence yield. Instead, we find, besides ionic interactions, a covalent contribution to the bonding in the aqueous complex of ligand-to-metal charge-transfer character.
Y1  - 2012
U6  - https://doi.org/10.1021/jz301486u
SN  - 1948-7185
VL  - 3
IS  - 23
SP  - 3448
EP  - 3453
PB  - American Chemical Society
CY  - Washington
ER  - 
TY  - GEN
A1  - Niskanen, Johannes
A1  - Kooser, Kuno
A1  - Koskelo, Jaakko
A1  - Käämbre, Tanel
A1  - Kunnus, Kristjan
A1  - Pietzsch, Annette
A1  - Quevedo, Wilson
A1  - Hakala, Mikko
A1  - Föhlisch, Alexander
A1  - Huotari, Simo
A1  - Kukk, Edwin
T1  - Density functional simulation of resonant inelastic X-ray scattering experiments in liquids: acetonitrile
N2  - In this paper we report an experimental and computational study of liquid acetonitrile (H3C–C[triple bond, length as m-dash]N) by resonant inelastic X-ray scattering (RIXS) at the N K-edge. The experimental spectra exhibit clear signatures of the electronic structure of the valence states at the N site and incident-beam-polarization dependence is observed as well. Moreover, we find fine structure in the quasielastic line that is assigned to finite scattering duration and nuclear relaxation. We present a simple and light-to-evaluate model for the RIXS maps and analyze the experimental data using this model combined with ab initio molecular dynamics simulations. In addition to polarization-dependence and scattering-duration effects, we pinpoint the effects of different types of chemical bonding to the RIXS spectrum and conclude that the H2C–C[double bond, length as m-dash]NH isomer, suggested in the literature, does not exist in detectable quantities. We study solution effects on the scattering spectra with simulations in liquid and in vacuum. The presented model for RIXS proved to be light enough to allow phase-space-sampling and still accurate enough for identification of transition lines in physical chemistry research by RIXS.
T3  - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - 331 
Y1  - 2016
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-395133
ER  - 
TY  - JOUR
A1  - Kunnus, Kristjan
A1  - Josefsson, Ida
A1  - Rajkovic, Ivan
A1  - Schreck, Simon
A1  - Quevedo, Wilson
A1  - Beye, Martin
A1  - Grübel, Sebastian
A1  - Scholz, Mirko
A1  - Nordlund, Dennis
A1  - Zhang, Wenkai
A1  - Hartsock, Robert W.
A1  - Gaffney, Kelly J.
A1  - Schlotter, William F.
A1  - Turner, Joshua J.
A1  - Kennedy, Brian
A1  - Hennies, Franz
A1  - Techert, Simone
A1  - Wernet, Philippe
A1  - Odelius, Michael
A1  - Föhlisch, Alexander
T1  - Anti-Stokes resonant x-ray Raman scattering for atom specific and excited state selective dynamics
JF  - NEW JOURNAL OF PHYSICS
N2  - Ultrafast electronic and structural dynamics of matter govern rate and selectivity of chemical reactions, as well as phase transitions and efficient switching in functional materials. Since x-rays determine electronic and structural properties with elemental, chemical, orbital and magnetic selectivity, short pulse x-ray sources have become central enablers of ultrafast science. Despite of these strengths, ultrafast x-rays have been poor at picking up excited state moieties from the unexcited ones. With time-resolved anti-Stokes resonant x-ray Raman scattering (AS-RXRS) performed at the LCLS, and ab initio theory we establish background free excited state selectivity in addition to the elemental, chemical, orbital and magnetic selectivity of x-rays. This unparalleled selectivity extracts low concentration excited state species along the pathway of photo induced ligand exchange of Fe(CO)(5) in ethanol. Conceptually a full theoretical treatment of all accessible insights to excited state dynamics with AS-RXRS with transform-limited x-ray pulses is given-which will be covered experimentally by upcoming transform-limited x-ray sources.
KW  - ultrafast photochemistry
KW  - excited state selectivity
KW  - anti-Stokes resonant x-ray raman scattering
KW  - free electron lasers
KW  - resonant inelastic x-ray scattering
Y1  - 2016
U6  - https://doi.org/10.1088/1367-2630/18/10/103011
SN  - 1367-2630
VL  - 18
PB  - IOP Publ. Ltd.
CY  - Bristol
ER  - 
TY  - JOUR
A1  - Kunnus, Kristjan
A1  - Rajkovic, Ivan
A1  - Schreck, Simon
A1  - Quevedo, Wilson
A1  - Eckert, Sebastian
A1  - Beye, Martin
A1  - Suljoti, Edlira
A1  - Weniger, Christian
A1  - Kalus, Christian
A1  - Gruebel, Sebastian
A1  - Scholz, Mirko
A1  - Nordlund, Dennis
A1  - Zhang, Wenkai
A1  - Hartsock, Robert W.
A1  - Gaffney, Kelly J.
A1  - Schlotter, William F.
A1  - Turner, Joshua J.
A1  - Kennedy, Brian
A1  - Hennies, Franz
A1  - Techert, Simone
A1  - Wernet, Philippe
A1  - Föhlisch, Alexander
T1  - A setup for resonant inelastic soft x-ray scattering on liquids at free electron laser light sources
JF  - Review of scientific instruments : a monthly journal devoted to scientific instruments, apparatus, and techniques
N2  - We present a flexible and compact experimental setup that combines an in vacuum liquid jet with an x-ray emission spectrometer to enable static and femtosecond time-resolved resonant inelastic soft x-ray scattering (RIXS) measurements from liquids at free electron laser (FEL) light sources. We demonstrate the feasibility of this type of experiments with the measurements performed at the Linac Coherent Light Source FEL facility. At the FEL we observed changes in the RIXS spectra at high peak fluences which currently sets a limit to maximum attainable count rate at FELs. The setup presented here opens up new possibilities to study the structure and dynamics in liquids.
Y1  - 2012
U6  - https://doi.org/10.1063/1.4772685
SN  - 0034-6748
VL  - 83
IS  - 12
PB  - American Institute of Physics
CY  - Melville
ER  -