Search

Your search keyword '"Schünemann V"' showing total 344 results
Start Over Author "Schünemann V"
344 results on '"Schünemann V"'

1. Density functional theory calculations and vibrational spectroscopy on iron spin-crossover compounds

Author

Wolny, J. A., Paulsen, H., Trautwein, A. X., and Schünemann, V.

Subjects
Physics - Chemical Physics
Abstract

Iron complexes with a suitable ligand field undergo spin-crossover (SCO), which can be induced reversibly by temperature, pressure or even light. Therefore, these compounds are highly interesting candidates for optical information storage, for display devices and pressure sensors. The SCO phenomenon can be conveniently studied by spectroscopic techniques like Raman and infrared spectroscopy as well as nuclear inelastic scattering, a technique which makes use of the M\"ossbauer effect. This review covers new developments which have evolved during the last years like, e.g. picosecond infrared spectroscopy and thin film studies but also gives an overviewon newtechniques for the theoretical calculation of spin transition phenomena and vibrational spectroscopic data of SCO complexes.

Published
2012
Full Text
View/download PDF

2. Importance of correlation effects in hcp iron revealed by a pressure-induced electronic topological transition

Author

Glazyrin, K., Pourovskii, L. V., Dubrovinsky, L., Narygina, O., McCammon, C., Hewener, B., Schünemann, V., Wolny, J., Muffler, K., Chumakov, A. I., Crichton, W., Hanfland, M., Prakapenka, V., Tasnádi, F., Ekholm, M., Aichhorn, M., Vildosola, V., Ruban, A. V., Katsnelson, M. I., and Abrikosov, I. A.

Subjects
Condensed Matter - Materials Science
Abstract

We discover that hcp phases of Fe and Fe0.9Ni0.1 undergo an electronic topological transition at pressures of about 40 GPa. This topological change of the Fermi surface manifests itself through anomalous behavior of the Debye sound velocity, c/a lattice parameter ratio and M\"ossbauer center shift observed in our experiments. First-principles simulations within the dynamic mean field approach demonstrate that the transition is induced by many-electron effects. It is absent in one-electron calculations and represents a clear signature of correlation effects in hcp Fe.

Published
2012
Full Text
View/download PDF

3. Spectral sensitive phonon wipeout due to a fluctuating spin state in a Fe2+ coordination polymer

Author

Gnezdilov, V., Lemmens, P., Scheib, P., Ghosh, M., Pashkevich, Yu. G., Paulsen, H., Schuenemann, V., Wolny, J. A., Agusti, G., and Real, J. A.

Subjects
Condensed Matter - Strongly Correlated Electrons, Condensed Matter - Materials Science, Condensed Matter - Soft Condensed Matter
Abstract

Raman scattering in the spin-crossover system [Fe(pmd)(H2O){Au(CN)2}2]*H2O reveals a complex three-phase spin-state transition in contrast to earlier observations in magnetization measurements. We observe different spin state phases as function of temperature and electromagnetic radiation in the visible spectral range. There exists a fluctuating spin state phase with an unexpected wipeout of the low frequency phonon scattering intensity. Furthermore we observe one phase with reduced symmetry that is attributed to a cooperative Jahn-Teller effect. Pronounced electron-phonon interaction manifests itself as a strong Fano-resonance of phonons related to {FeN6} and {FeN4O2} coordination octahedra. Density functional theory supports this interpretation., Comment: 9 pages, 9 figures, 3 tables

Published
2009
Full Text
View/download PDF

16. Complete Mitochondrial Genomes of Ancient Canids Suggest a European Origin of Domestic Dogs

Author

Thalmann, O., Shapiro, B., Cui, P., Schuenemann, V. J., Sawyer, S. K., Greenfield, D. L., Germonpré, M. B., Sablin, M. V., López-Giráldez, F., Domingo-Roura, X., Napierala, H., Uerpmann, H-P., Loponte, D. M., Acosta, A. A., Giemsch, L., Schmitz, R. W., Worthington, B., Buikstra, J. E., Druzhkova, A., Graphodatsky, A. S., Ovodov, N. D., Wahlberg, N., Freedman, A. H., Schweizer, R. M., Koepfli, K.-P., Leonard, J. A., Meyer, M., Krause, J., Pääbo, S., Green, R. E., and Wayne, R. K.

Published
2013
Full Text
View/download PDF

23. Electron inventory of the iron-sulfur scaffold complex HypCD essential in [NiFe]-hydrogenase cofactor assembly

Author

Stripp, S.T., Oltmanns, J., Müller, C.S., Ehrenberg, D., Schlesinger, R., Heberle, J., Adrian, Lorenz, Schünemann, V., Pierik, A.J., Soboh, B., Stripp, S.T., Oltmanns, J., Müller, C.S., Ehrenberg, D., Schlesinger, R., Heberle, J., Adrian, Lorenz, Schünemann, V., Pierik, A.J., and Soboh, B.

Abstract

The [4Fe-4S] cluster containing scaffold complex HypCD is the central construction site for the assembly of the [Fe](CN)2CO cofactor precursor of [NiFe]-hydrogenase. While the importance of the HypCD complex is well established, not much is known about the mechanism by which the CN- and CO ligands are transferred and attached to the iron ion. We report an efficient expression and purification system producing the HypCD complex from E. coli with complete metal content. This enabled in-depth spectroscopic characterizations. The results obtained by EPR and Mössbauer spectroscopy demonstrate that the [Fe](CN)2CO cofactor and the [4Fe-4S] cluster of the HypCD complex are redox active. The data indicate a potential-dependent interconversion of the [Fe]2+/3+ and [4Fe-4S]2+/+ couple, respectively. Moreover, ATR FTIR spectroscopy reveals potential-dependent disulfide formation, which hints at an electron confurcation step between the metal centers. MicroScale thermophoresis indicates preferable binding between the HypCD complex and its in vivo interaction partner HypE under reducing conditions. Together, these results provide comprehensive evidence for an electron inventory fit to drive multi-electron redox reactions required for the assembly of the CN- and CO ligands on the scaffold complex HypCD.

Published
2021

31. Dynamics of metal centers monitored by nuclear inelastic scattering

Author

Paulsen, H., primary, Wegner, P., additional, Winkler, H., additional, Wolny, J. A., additional, Böttger, L. H., additional, Trautwein, A. X., additional, Schmidt, C., additional, Schünemann, V., additional, Barone, G., additional, Silvestri, A., additional, La Manna, G., additional, Chumakov, A. I., additional, Sergueev, I., additional, and Rüffer, R., additional

Published
2006
Full Text
View/download PDF

35. Iron Clusters in Zeolites

Author

Schünemann, V., primary, Winkler, H., additional, Ziethen, H.M., additional, Schiller, A., additional, and Trautwein, A.X., additional

Published
1992
Full Text
View/download PDF

43. Effects of mechanical loading on the magnetic and dynamic properties of engineering materials

Author

Scherthan, L., primary, Auerbach, H., additional, Deldar, S., additional, Jenni, K., additional, Wolny, J. A., additional, Herlitschke, M., additional, Wille, H. -C., additional, Mutter, A., additional, Meiser, J., additional, Umstätter, P., additional, Urbassek, H. M., additional, Beck, T., additional, Smaga, M., additional, and Schünemann, V., additional

Published
2017
Full Text
View/download PDF

47. Nuclear resonant scattering of synchrotron radiation by $^{187}$ Os

Author

Bessas, D., Sergueev, I., Sadler, P. J., Hermann, Raphael, Merkel, D. G., Chumakov, A. I., Rüffer, R., Jafari, A., Kishimoto, S., Wolny, J. A., Schünemann, V., and Needham, R. J.

Subjects
ddc:530
Abstract

We performed nuclear forward and inelastic scattering of synchrotron radiation by elemental Os utilizing the nuclear excited state of Os187 which is otherwise inaccessible using any practical radioactive decay process. The lifetime of the excited state, 3.06(8)ns, and the energy of the transition, 9.778(3)keV, are refined. The nuclear quadrupole moment of the excited state, Q3/2=1.46(10)b, is determined. The density of phonon states for elemental Os, which is herein experimentally determined, suggests that the Os lattice is a model for the lattice dynamics of hcp-Fe. The combination of the low energy of the nuclear transition and the large nuclear mass leads to a high recoil free fraction, fLM=0.95(1), at room temperature, a large value that strongly supports the viability of nuclear resonance scattering as a reliable method to study electronic, magnetic, and elastic properties of Os compounds, including Os organometallics.

Published
2015

49. Nuclear Inelastic Scattering Study of a Fluorophore-Tagged Dinuclear Iron(II) Spin Crossover Complex (poster)

Author

UCL - SST/IMCN/MOST - Molecules, Solids and Reactivity, Wolny, J. A., Faus, I., Garcia, Yann, Rackwitz, S., Schlage, K., Wille, H. C., Schünemann, V., International Conference on the Applications of the Mössbauer effect (ICAME 2015), UCL - SST/IMCN/MOST - Molecules, Solids and Reactivity, Wolny, J. A., Faus, I., Garcia, Yann, Rackwitz, S., Schlage, K., Wille, H. C., Schünemann, V., and International Conference on the Applications of the Mössbauer effect (ICAME 2015)

Published
2015

50. Nuclear resonant scattering of synchrotron radiation byOs187

Author

Bessas, D., primary, Sergueev, I., additional, Merkel, D. G., additional, Chumakov, A. I., additional, Rüffer, R., additional, Jafari, A., additional, Kishimoto, S., additional, Wolny, J. A., additional, Schünemann, V., additional, Needham, R. J., additional, Sadler, P. J., additional, and Hermann, R. P., additional

Published
2015
Full Text
View/download PDF

Catalog

Books, media, physical & digital resources
See catalog results