THEORY DEPARTMENT
Fritz Haber Institute of the Max Planck Society

All FHI Seminars

Flexibilisierungsoptionen für fluktuierende erneuerbare Energien zur Nutzung von Überschussstrom – Metastudie
Speaker:Diogenis Lazaridis
 TU Berlin/Deutscher Bundestag
Time:Monday, 18th February 2019, 10:00 AM
Location: AC Seminar Room, Building F, room 0.04
Organized: AC
Abstract: Der Vortrag skizziert den geplanten Inhalt der Masterarbeit, die Ende August 2019 abgeschlossen sein soll. Ziel der Arbeit ist es, die bisherigen Forschungserkenntnisse der Flexibilisierungsoptionen zur Nutzung von potentieller, zeitweise auftretender negativer Residuallast durch nicht regelbare erneuerbare Energien zu vergleichen und zu bewerten. Im Rahmen dessen sollen mögliche Flexibilitätsoptionen identifiziert und analysiert werden. Insbesondere Möglichkeiten aus dem Themenfeld der Digitalisierung im Strombereich und der Optimierung von Wetterprognosen zur Vorhersage von Wind- und Sonnenenergie sollen je nach Studienlage Einzug in die Arbeit finden. Weiterhin sollen Handlungsempfehlungen für eine erfolgreiche Integration der fluktuierenden erneuerbaren Energien auf Basis der gewonnenen Erkenntnisse gegeben werden und das Potenzial für weitere Untersuchungen und Forschung in diesem Themengebiet aufgezeigt werden.

Technical handbook for assembly of clean data in selective oxidation
Speaker:Robert Schlögl/Annette Trunschke
 FHI, AC Dept.
Time:Monday, 18th February 2019, 1:00 PM
Location: AC Seminar Room, Building F, room 0.04
Organized: AC
Abstract: Abstract: The synthesis of value-added intermediates starting form abundant resources, such as alkanes or synthesis gas, requires sophisticated catalysts and the control of selectivity to specific products is complicated by the underlying complex organic reaction networks in reactions like the selective oxidation of alkanes,[1] or the synthesis of higher alcohols by CO2/CO hydrogenation.[2,3] Empirical concepts exist, but a comprehensive theory that predicts reactivity is missing. Big data analysis and methods of data mining and machine learning are currently undergoing renewed interest in heterogeneous catalysis with the aim to discover catalysts with improved performance in reactions that are influenced by a multitude of parameters.[4,5] Data science requires extensive datasets that contain reliable experimental data. In a pilot project, we will generate a comprehensive set of experimental results for 10 oxidation catalysts that will be studied in selective oxidation if C2-C4 alkanes. The applicability of the generated data for data analysis will then be discussed. The work will be performed in close collaboration with the BasCat laboratory at the TU Berlin and the Department of Theory of the FHI. To assure the quality of the data, the measurement procedure is described in a technical handbook. The handbook will be presented in the seminar. (1) Kube, P.; Frank, B.; Schlögl, R.; Trunschke, A., Isotope Studies in Oxidation of Propane over Vanadium Oxide. ChemCatChem 2017, 9, 3446 – 3455. (2) Mei, D.; Rousseau, R.; Kathmann, S. M.; Glezakou, V.-A.; Engelhard, M. H.; Jiang, W.; Wang, C.; Gerber, M. A.; White, J. F.; Stevens, D. J., Ethanol synthesis from syngas over Rh-based/SiO2 catalysts: A combined experimental and theoretical modeling study. Journal of Catalysis 2010, 271, 325-342. (3) Cao, A.; Schumann, J.; Wang, T.; Zhang, L.; Xiao, J.; Bothra, P.; Liu, Y.; Abild-Pedersen, F.; Nørskov, J. K., Mechanistic Insights into the Synthesis of Higher Alcohols from Syngas on CuCo Alloys. ACS Catalysis 2018, 8, 10148-10155. (4) Kitchin, J. R., Machine learning in catalysis. Nature Catalysis 2018, 1, 230-232. (5) Ghiringhelli, L. M.; Vybiral, J.; Levchenko, S. V.; Draxl, C.; Scheffler, M., Big Data of Materials Science: Critical Role of the Descriptor. Physical Review Letters 2015, 114, 105503.

Aqueous Interfaces Investigated Under Ambient Conditions by XPS
Speaker:Dr. Hendrik Bluhm
 Fritz-Haber-Institut, Inorganic Chemistry
Time:Friday, 22nd February 2019, 9:30 AM
Location: Haber-Villa, Faradayweg 8
Organized: MP
Abstract: Aqueous interfaces are ubiquitous in technological applications and in the environment and govern numerous important phenomena, including corrosion, photoelectrochemical splitting of water, weathering of rocks, cloud droplet nucleation, the concentration of trace gases in polar regions, and CO2 sequestration by the oceans. A detailed understanding of these processes requires the investigation of aqueous interfaces with chemical sensitivity and interface specificity under ambient conditions, i.e., temperatures above 200 K and water vapour pressures in the milliTorr to tens of Torr pressure range. Ambient pressure X-ray photoelectron spectroscopy has been used to investigate a number of different aqueous interfaces, including ultrathin water films on metals and oxides, bulk liquid/solid interfaces, the surface of aqueous solutions in the presence of the equilibrium vapour pressure as well as trace gases, and the surface of ice, which at temperatures close to the melting point is covered by a thin liquid-like. The challenge for XPS experiments on aqueous interfaces under ambient conditions is not only the elevated pressure at which these experiments have to be carried out, but equally so the preparation of clean, well controlled aqueous samples with high cleanliness and reproducibility. In this talk I will review the progress that has been made in the area of APXPS experiments on aqueous systems and provide an outlook on opportunities for future research in this field.

Photoelectron Circular Dichroism: from Single Photon to Strong Fields and from Static to Attosecond Dynamics
Speaker:Dr. Samuel Beaulieu
 Fritz-Haber-Institut, Physical Chemistry
Time:Friday, 15th March 2019, 8:30 AM
Location: Haber-Villa, Faradayweg 8
Organized: MP
Abstract: Abstract: Photoionization of randomly oriented chiral molecules with chiral light leads to a strong forward/backward asymmetry in the photoelectron angular distribution (PAD) [1]. This effect is called Photoelectron Circular Dichroism (PECD). PECD finds its origin in the forward/backward (F/B) asymmetry of the photoelectron scattering phases. Since its discovery, PECD has mainly been studied in single photon ionization regime using synchrotron facilities [2,3]. Recently, pioneering experiments have shown that PECD also exists in [2+1] resonant enhanced multiphoton ionization using table-top femtosecond lasers [4,5]. In this talk, I will present results about the photoionization of chiral molecules using circular light in all ionization regimes, starting from the single photon regime and ending in the tunnel ionization regime. We will see that PECD is a universal effect, meaning that chiral character of the molecular potential is able to imprint its signature onto the PAD, whatever the ionization regime [6]. Furthermore, we will bridge the gap between PECD and attosecond science by performing attosecond electron interferometry measurements. These experiments allow the direct measurement of the forward/backward asymmetry of the photoelectron scattering phases, which are at the origin of PECD. We have also used those data to reconstruct the temporal structures of the forward and backward outgoing electron wavepackets [7]. Upon non-resonant photoionization, we have measured a difference of sub-10 as for the electrons emitted in the forward or backward direction. Moreover, in the vicinity of an autoionizing state, the structured electron wavepackets are strongly asymmetric, revealing the chiral character of multielectronic effects [8]. References 1. Ritchie, B., Phys. Rev. A 13, 1411 (1976) 2. Böwering, N. et al., Phys. Rev. Lett. 86, 1187 (2001) 3. Nahon, L. et al., Journal of Electron Spectroscopy and Related Phenomena 204, 322–334 (2015). 4. Lux, C. et al., Angew. Chem. 51, 5001 (2012) 5. Lehmann, C. S. et al., J. Chem. Phys. 139, 234307 (2013) 6. Beaulieu, S. et al., New Journal of Physics 18 (10), 102002 (2016) 7. Gruson, V. et al., Science 354, 734–738 (2016) 8. Beaulieu, S. et al, Science 358, 1288–1294 (2017)

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