TY  - JOUR
A1  - Sun, Y. -P.
A1  - Hennies, Franz
A1  - Pietzsch, Annette
A1  - Kennedy, B.
A1  - Schmitt, Thorsten
A1  - Strocov, Vladimir N.
A1  - Andersson, Joakim
A1  - Berglund, Martin
A1  - Rubensson, Jan-Erik
A1  - Aidas, K.
A1  - Gel'mukhanov, F.
A1  - Odelius, Michael
A1  - Föhlisch, Alexander
T1  - Intramolecular soft modes and intermolecular interactions in liquid acetone
JF  - Physical review : B, Condensed matter and materials physics
N2  - Resonant inelastic x-ray scattering spectra excited at the O1s(-1)pi* resonance of liquid acetone are presented. Scattering to the electronic ground state shows a resolved vibrational progression where the dominant contribution is due to the C-O stretching mode, thus demonstrating a unique sensitivity of the method to the local potential energy surface in complex molecular systems. For scattering to electronically excited states, soft vibrational modes and, to a smaller extent, intermolecular interactions give a broadening, which blurs the vibrational fine structure. It is predicted that environmental broadening is dominant in aqueous acetone.
Y1  - 2011
U6  - https://doi.org/10.1103/PhysRevB.84.132202
SN  - 1098-0121
VL  - 84
IS  - 13
PB  - American Physical Society
CY  - College Park
ER  - 
TY  - JOUR
A1  - Pietzsch, Annette
A1  - Sun, Y. -P.
A1  - Hennies, Franz
A1  - Rinkevicius, Z.
A1  - Karlsson, Hans O.
A1  - Schmitt, Thorsten
A1  - Strocov, Vladimir N.
A1  - Andersson, Joakim
A1  - Kennedy, B.
A1  - Schlappa, J.
A1  - Föhlisch, Alexander
A1  - Rubensson, Jan-Erik
A1  - Gel'mukhanov, F.
T1  - Spatial quantum beats in vibrational resonant inelastic soft X-ray scattering at dissociating states in oxygen
JF  - Physical review letters
N2  - Resonant inelastic soft x-ray scattering (RIXS) spectra excited at the 1 sigma(g) -> 3 sigma(u) resonance in gas-phase O-2 show excitations due to the nuclear degrees of freedom with up to 35 well-resolved discrete vibronic states and a continuum due to the kinetic energy distribution of the separated atoms. The RIXS profile demonstrates spatial quantum beats caused by two interfering wave packets with different momenta as the atoms separate. Thomson scattering strongly affects both the spectral profile and the scattering anisotropy.
Y1  - 2011
U6  - https://doi.org/10.1103/PhysRevLett.106.153004
SN  - 0031-9007
VL  - 106
IS  - 15
PB  - American Physical Society
CY  - College Park
ER  - 
TY  - JOUR
A1  - Pietzsch, Annette
A1  - Hennies, Franz
A1  - Miedema, Piter S.
A1  - Kennedy, Brian
A1  - Schlappa, Justine
A1  - Schmitt, Thorsten
A1  - Strocov, Vladimir N.
A1  - Föhlisch, Alexander
T1  - Snapshots of the Fluctuating Hydrogen Bond Network in Liquid Water on the Sub-Femtosecond Timescale with Vibrational Resonant Inelastic x-ray Scattering
JF  - Physical review letters
N2  - Liquid water molecules interact strongly with each other, forming a fluctuating hydrogen bond network and thereby giving rise to the anomalous phase diagram of liquid water. Consequently, symmetric and asymmetric water molecules have been found in the picosecond time average with IR and optical Raman spectroscopy. With subnatural linewidth resonant inelastic x-ray scattering (RIXS) at vibrational resolution, we take sub-femtosecond snapshots of the electronic and structural properties of water molecules in the hydrogen bond network. We derive a strong dominance of nonsymmetric molecules in liquid water in contrast to the gas phase on the sub-femtosecond timescale of RIXS and determine the fraction of highly asymmetrically distorted molecules.
Y1  - 2015
U6  - https://doi.org/10.1103/PhysRevLett.114.088302
SN  - 0031-9007
SN  - 1079-7114
VL  - 114
IS  - 8
PB  - American Physical Society
CY  - College Park
ER  - 
TY  - JOUR
A1  - Arhammar, C.
A1  - Pietzsch, Annette
A1  - Bock, Nicolas
A1  - Holmstroem, Erik
A1  - Araujo, C. Moyses
A1  - Grasjo, Johan
A1  - Zhao, Shuxi
A1  - Green, Sara
A1  - Peery, T.
A1  - Hennies, Franz
A1  - Amerioun, Shahrad
A1  - Föhlisch, Alexander
A1  - Schlappa, Justine
A1  - Schmitt, Thorsten
A1  - Strocov, Vladimir N.
A1  - Niklasson, Gunnar A.
A1  - Wallace, Duane C.
A1  - Rubensson, Jan-Erik
A1  - Johansson, Borje
A1  - Ahuja, Rajeev C.
T1  - Unveiling the complex electronic structure of amorphous metal oxides
JF  - Proceedings of the National Academy of Sciences of the United States of America
N2  - Amorphous materials represent a large and important emerging area of material's science. Amorphous oxides are key technological oxides in applications such as a gate dielectric in Complementary metal-oxide semiconductor devices and in Silicon-Oxide-Nitride-Oxide-Silicon and TANOS (TaN-Al2O3-Si3N4-SiO2-Silicon) flash memories. These technologies are required for the high packing density of today's integrated circuits. Therefore the investigation of defect states in these structures is crucial. In this work we present X-ray synchrotron measurements, with an energy resolution which is about 5-10 times higher than is attainable with standard spectrometers, of amorphous alumina. We demonstrate that our experimental results are in agreement with calculated spectra of amorphous alumina which we have generated by stochastic quenching. This first principles method, which we have recently developed, is found to be superior to molecular dynamics in simulating the rapid gas to solid transition that takes place as this material is deposited for thin film applications. We detect and analyze in detail states in the band gap that originate from oxygen pairs. Similar states were previously found in amorphous alumina by other spectroscopic methods and were assigned to oxygen vacancies claimed to act mutually as electron and hole traps. The oxygen pairs which we probe in this work act as hole traps only and will influence the information retention in electronic devices. In amorphous silica oxygen pairs have already been found, thus they may be a feature which is characteristic also of other amorphous metal oxides.
KW  - stochastic quench
KW  - X-ray absorption spectroscopy
KW  - ab initio
KW  - coating
Y1  - 2011
U6  - https://doi.org/10.1073/pnas.1019698108
SN  - 0027-8424
VL  - 108
IS  - 16
SP  - 6355
EP  - 6360
PB  - National Acad. of Sciences
CY  - Washington
ER  - 
TY  - JOUR
A1  - Sun, Y-P
A1  - Pietzsch, Annette
A1  - Hennies, Franz
A1  - Rinkevicius, Z.
A1  - Karlsson, Hans O.
A1  - Schmitt, Thorsten
A1  - Strocov, Vladimir N.
A1  - Andersson, Joakim
A1  - Kennedy, B.
A1  - Schlappa, J.
A1  - Föhlisch, Alexander
A1  - Gel'mukhanov, F.
A1  - Rubensson, Jan-Erik
T1  - Internal symmetry and selection rules in resonant inelastic soft x-ray scattering
JF  - Journal of physics : B, Atomic, molecular and optical physics
N2  - Resonant inelastic soft x-ray scattering spectra excited at the dissociative 1 sigma(g) -> 3 sigma(u) resonance in gas-phase O(2) are presented and discussed in terms of state-of-the-art molecular theory. A new selection rule due to internal spin coupling is established, facilitating a deep analysis of the valence excited final states. Furthermore, it is found that a commonly accepted symmetry selection rule due to orbital parity breaks down, as the core hole and excited electron swap parity, thereby opening the symmetry forbidden 3 sigma(g) decay channel.
Y1  - 2011
U6  - https://doi.org/10.1088/0953-4075/44/16/161002
SN  - 0953-4075
VL  - 44
IS  - 16
PB  - IOP Publ. Ltd.
CY  - Bristol
ER  - 
TY  - JOUR
A1  - Rubensson, Jan-Erik
A1  - Soderstrom, Johan
A1  - Binggeli, Christian
A1  - Grasjo, Joakim
A1  - Andersson, Johan
A1  - Sathe, Conny
A1  - Hennies, Franz
A1  - Bisogni, Valentina
A1  - Huang, Yaobo
A1  - Olalde, Paul
A1  - Schmitt, Thorsten
A1  - Strocov, Vladimir N.
A1  - Föhlisch, Alexander
A1  - Kennedy, Brian
A1  - Pietzsch, Annette
T1  - Rydberg-Resolved Resonant Inelastic Soft X-Ray Scattering: Dynamics at Core Ionization Thresholds
JF  - Physical review letters
N2  - Resonant inelastic x-ray scattering spectra excited in the immediate vicinity of the core-level ionization thresholds of N-2 have been recorded. Final states of well-resolved symmetry-selected Rydberg series converging to valence-level ionization thresholds with vibrational excitations are observed. The results are well described by a quasi-two-step model which assumes that the excited electron is unaffected by the radiative decay. This threshold dynamics simplifies the interpretation of resonant inelastic x-ray scattering spectra considerably and facilitates characterization of low-energy excited final states in molecular systems.
Y1  - 2015
U6  - https://doi.org/10.1103/PhysRevLett.114.133001
SN  - 0031-9007
SN  - 1079-7114
VL  - 114
IS  - 13
PB  - American Physical Society
CY  - College Park
ER  - 
TY  - JOUR
A1  - Schreck, Simon
A1  - Pietzsch, Annette
A1  - Kennedy, Brian
A1  - Sathe, Conny
A1  - Miedema, Piter S.
A1  - Techert, Simone
A1  - Strocov, Vladimir N.
A1  - Schmitt, Thorsten
A1  - Hennies, Franz
A1  - Rubensson, Jan-Erik
A1  - Föhlisch, Alexander
T1  - Ground state potential energy surfaces around selected atoms from resonant inelastic x-ray scattering
JF  - Scientific reports
N2  - Thermally driven chemistry as well as materials’ functionality are determined by the potential energy surface of a systems electronic ground state. This makes the potential energy surface a central and powerful concept in physics, chemistry and materials science. However, direct experimental access to the potential energy surface locally around atomic centers and to its long-range structure are lacking. Here we demonstrate how sub-natural linewidth resonant inelastic soft x-ray scattering at vibrational resolution is utilized to determine ground state potential energy surfaces locally and detect long-range changes of the potentials that are driven by local modifications. We show how the general concept is applicable not only to small isolated molecules such as O2 but also to strongly interacting systems such as the hydrogen bond network in liquid water. The weak perturbation to the potential energy surface through hydrogen bonding is observed as a trend towards softening of the ground state potential around the coordinating atom. The instrumental developments in high resolution resonant inelastic soft x-ray scattering are currently accelerating and will enable broad application of the presented approach. With this multidimensional potential energy surfaces that characterize collective phenomena such as (bio)molecular function or high-temperature superconductivity will become accessible in near future.
Y1  - 2016
U6  - https://doi.org/10.1038/srep20054
SN  - 2045-2322
VL  - 6
PB  - Nature Publ. Group
CY  - London
ER  -